draft-ietf-bmwg-mswitch-01.txt   draft-ietf-bmwg-mswitch-02.txt 
Network Working Group R. Mandeville Network Working Group R. Mandeville
Internet-Draft European Network Laboratories Internet-Draft European Network Laboratories
Expiration Date: November 1999 J. Perser Expiration Date: May 2000 J. Perser
Netcom Systems Netcom Systems
May 1999 November 1999
Benchmarking Methodology for LAN Switching Devices Benchmarking Methodology for LAN Switching Devices
<draft-ietf-bmwg-mswitch-01.txt> <draft-ietf-bmwg-mswitch-02.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
skipping to change at page 1, line 34 skipping to change at page 1, line 34
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Test setup . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3. Test setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
4. Frame formats and sizes . . . . . . . . . . . . . . . . . . . . 3 4. Frame formats and sizes . . . . . . . . . . . . . . . . . . . . . 3
5. Benchmarking Tests . . . . . . . . . . . . . . . . . . . . . . 4 5. Benchmarking Tests . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1 Fully meshed throughput, frame loss and forwarding rates . . 4 5.1 Fully meshed throughput, frame loss and forwarding rates . . 4
5.2 Partially meshed overloading . . . . . . . . . . . . . . . . 7 5.2 Partially meshed one-to-many/many-to-one . . . . . . . . . . 7
5.3 Head of line blocking . . . . . . . . . . . . . . . . . . . . 10 5.3 Partially meshed multiple devices . . . . . . . . . . . . . . 10
5.4 Partially meshed multiple devices . . . . . . . . . . . . . . 13 5.4 Partially meshed unidirectional traffic . . . . . . . . . . . 13
5.5 Multiple streams of unidirectional traffic . . . . . . . . . 15 5.5 Congestion Control . . . . . . . . . . . . . . . . . . . . . 16
5.6 Filter illegal frames . . . . . . . . . . . . . . . . . . . . 18 5.6 Forward Pressure and Maximum Forwarding Rate . . . . . . . . 19
5.7 Broadcast frame handling and latency . . . . . . . . . . . . 20 5.7 Address caching capacity . . . . . . . . . . . . . . . . . . 21
5.8 Maximum forwarding rate and minimum interframe gap . . . . . 21 5.8 Address learning rate . . . . . . . . . . . . . . . . . . . . 24
5.9 Address caching capacity . . . . . . . . . . . . . . . . . . 23 5.9 Errored frames filtering. . . . . . . . . . . . . . . . . . . 26
5.10 Address learning rate . . . . . . . . . . . . . . . . . . . . 26 5.10 Broadcast frame Forwarding and Latency . . . . . . . . . . . 28
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 28 6. Security Considerations . . . . . . . . . . . . . . . . . . . . . 29
7. Authors' Address . . . . . . . . . . . . . . . . . . . . . . . 28 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Appendix A: Formulas . . . . . . . . . . . . . . . . . . . . . . 29 8. Authors' Address . . . . . . . . . . . . . . . . . . . . . . . . . 30
Appendix A: Formulas . . . . . . . . . . . . . . . . . . . . . . . 31
Appendix B: Generating Offered Load . . . . . . . . . . . . . . . 33
1. Introduction 1. Introduction
This document is intended to provide methodology for the benchmarking This document is intended to provide methodology for the benchmarking
of local area network (LAN) switching devices. It extends the of local area network (LAN) switching devices. It extends the
methodology already defined for benchmarking network interconnecting methodology already defined for benchmarking network interconnecting
devices in RFC 2544 to switching devices. devices in RFC 2544 [3] to switching devices.
This RFC primarily deals with devices which switch frames at the This RFC primarily deals with devices which switch frames at the
Medium Access Control (MAC) layer. It provides a methodology for Medium Access Control (MAC) layer. It provides a methodology for
benchmarking switching devices, forwarding performance, congestion benchmarking switching devices, forwarding performance, congestion
control, latency, address handling and filtering. In addition to control, latency, address handling and filtering. In addition to
defining the tests, this document also describes specific formats for defining the tests, this document also describes specific formats for
reporting the results of the tests. reporting the results of the tests.
A previous document, "Benchmarking Terminology for LAN Switching A previous document, "Benchmarking Terminology for LAN Switching
Devices" (RFC 2285), defined many of the terms that are used in this Devices" [2], defined many of the terms that are used in this
document. The terminology document SHOULD be consulted before document. The terminology document SHOULD be consulted before
attempting to make use of this document. attempting to make use of this document.
2. Requirements 2. Requirements
The following RFCs SHOULD be consulted before attempting to make use The following RFCs SHOULD be consulted before attempting to make use
of this document: of this document: RFC 1242 [1], RFC 2285 [2], and RFC 2544 [3].
* RFC 1242 "Benchmarking Terminology for Network Interconnect
Devices"
* RFC 2285 "Benchmarking Terminology for LAN Switching Devices"
* RFC 2544 "Benchmarking Methodology for Network Interconnect
Devices"
For the sake of clarity and continuity, this RFC adopts the template For the sake of clarity and continuity, this RFC adopts the template
for benchmarking tests set out in Section 26 of RFC 2544. for benchmarking tests set out in Section 26 of RFC 2544.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC 2119. this document are to be interpreted as described in RFC 2119.
3. Test setup 3. Test setup
This document extends the general test setup described in section 6 This document extends the general test setup described in section 6
of RFC 2544 to the benchmarking of LAN switching devices. RFC 2544 of RFC 2544 [3] to the benchmarking of LAN switching devices.
primarily describes non-meshed traffic where input and output RFC 2544 [3] primarily describes non-meshed traffic where input and
interfaces are grouped in mutually exclusive sending and receiving output interfaces are grouped in mutually exclusive sending and
pairs. In fully meshed traffic, each interface of a DUT/SUT is set receiving pairs. In fully meshed traffic, each interface of a
up to both receive and transmit frames to all the other interfaces DUT/SUT is set up to both receive and transmit frames to all the
under test. other interfaces under test.
Prior to each test run, the DUT/SUT MUST learn the MAC addresses used Prior to each test run, the DUT/SUT MUST learn the MAC addresses used
in the test and the address learning SHOULD be verified. Addresses in the test and the address learning SHOULD be verified. Addresses
not learned will be forwarded as flooded frames and reduce the amount not learned will be forwarded as flooded frames and reduce the amount
of correctly forwarded frames. The rate at which address learning of correctly forwarded frames. The rate at which address learning
frames are offered may have to be adjusted to be as low as 50 frames frames are offered may have to be adjusted to be as low as 50 frames
per second or even less, to guarantee successful learning. The per second or even less, to guarantee successful learning. The
DUT/SUT address aging time SHOULD be configured to be greater than DUT/SUT address aging time SHOULD be configured to be greater than
the period of the learning phase of the test plus the test duration the period of the learning phase of the test plus the trial duration
plus any configuration time required by the testing device. plus any configuration time required by the testing device.
Addresses SHOULD NOT age out until the test duration is completed. Addresses SHOULD NOT age out until the trial duration is completed.
More than one learning trial may be needed for the association of the More than one learning trial may be needed for the association of the
address to the port to occur. address to the port to occur.
If a DUT/SUT uses a hashing algorithm with address learning, the If a DUT/SUT uses a hashing algorithm with address learning, the
DUT/SUT may not learn the necessary addresses to perform the tests. DUT/SUT may not learn the necessary addresses to perform the tests.
The format of the MAC addresses MUST be adjustable so that the The format of the MAC addresses MUST be adjustable so that the
address mapping may be re-arranged to make a DUT/SUT learn addresses address mapping may be re-arranged to ensure that the DUT/SUT learns
without confusion. all the addresses.
It is recommended that SNMP and Spanning Tree be disabled when bench-
marking switching devices unless investigating overhead behavior. If
such protocols cannot be turned off, it is recommended that the
levels of offered load be reduced (less than 100%) to allow for
the additional management frames.
4. Frame formats and sizes 4. Frame formats and sizes
The frame format is defined in RFC 2544 section 8 and MUST contain a The test frame format is defined in RFC 2544 section 8 [3] and MUST
unique signature field located in the UDP DATA area of the Test Frame contain a unique signature field located in the UDP DATA area of the
(see Appendix C of RFC 2544). The purpose of the signature field is Test Frame (see Appendix C [3]). The purpose of the signature field
filter out frames that are not part of the offered load. is filter out frames that are not part of the offered load.
The signature field MUST be unique enough to identify the frames not The signature field MUST be unique enough to identify the frames not
originating from the DUT/SUT. The signature field SHOULD be located originating from the DUT/SUT. The signature field SHOULD be located
after byte 56 (ISO/IEC 8802-3 collision window) or at the end of the after byte 56 (collision window [4] ) or at the end of the frame.
frame. The length, contents and method of detection is not defined The length, contents and method of detection is not defined in this
in this memo. memo.
The signature field MAY have a unique identifier per port. This The signature field MAY have a unique identifier per port. This
would filter out misforwarded frames. It is possible for a DUT/SUT would filter out misforwarded frames. It is possible for a DUT/SUT
to strip off the MAC layer, send it through its switching matrix, to strip off the MAC layer, send it through its switching matrix,
and transmit it out with the correct destination MAC address but the and transmit it out with the correct destination MAC address but the
wrong payload. wrong payload.
For frame sizes, refer to RFC 2544, section 9. For frame sizes, refer to RFC 2544, section 9 [3].
There are three possible frame formats for layer 2 Ethernet switches: There are three possible frame formats for layer 2 Ethernet switches:
standard MAC Ethernet frames, standard MAC Ethernet frames standard MAC Ethernet frames, standard MAC Ethernet frames with
with vendor-specific tags added to them, and IEEE 802.3ac vendor-specific tags added to them, and IEEE 802.3ac frames tagged to
frames tagged to accommodate 802.3p&q. The two types of tagged accommodate 802.1p&Q. The two types of tagged frames may exceed the
frames may exceed the standard maximum length frame of 1518 bytes, standard maximum length frame of 1518 bytes, and may not be accepted
and may not be accepted by the interface controllers of some by the interface controllers of some DUT/SUTs. It is recommended to
DUT/SUTs. It is recommended to check the compatibility of the DUT/SUT check the compatibility of the DUT/SUT with tagged frames before
with tagged frames before testing. testing.
Devices switching tagged frames of over 1518 bytes will have a lower Devices switching tagged frames of over 1518 bytes will have a
maximum forwarding rate than standard untagged frames. different maximum forwarding rate than untagged frames.
5. Benchmarking Tests 5. Benchmarking Tests
The following tests offer objectives, procedures, and reporting The following tests offer objectives, procedures, and reporting
formats for benchmarking LAN switching devices. formats for benchmarking LAN switching devices.
5.1 Fully meshed throughput, frame loss and forwarding rates 5.1 Fully meshed throughput, frame loss and forwarding rates
5.1.1 Objective 5.1.1 Objective
To determine the throughput, frame loss and forwarding rates of To determine the throughput, frame loss and forwarding rates of
DUT/SUTs offered fully meshed traffic as defined in RFC 2285. DUT/SUTs offered fully meshed traffic as defined in RFC 2285 [2].
5.1.2 Setup Parameters 5.1.2 Setup Parameters
When offering bursty full meshed traffic, the following parameters When offering full meshed traffic, the following parameters MUST be
MUST be defined. Each parameter is configured with the following defined. Each parameter is configured with the following
considerations. considerations.
Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024, Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
1280 and 1518 bytes, per RFC 2544 section 9. The four CRC bytes 1280 and 1518 bytes, per RFC 2544 section 9 [3]. The four CRC
are included in the frame size specified. bytes are included in the frame size specified.
Interframe Gap (IFG) - The IFG between frames inside a burst Interframe Gap (IFG) - The IFG between frames inside a burst
MUST be at the minimum specified by the standard (9.6 us for MUST be at the minimum specified by the standard (9.6 us for
10Mbps Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for 10Mbps Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for
1 Gbps Ethernet). 1 Gbps Ethernet) of the medium being tested.
Interburst Gap (IBG) - This is the interval between bursts of
traffic. Refer to Appendix A Formulas, for the formula used to
compute IBG.
Duplex mode - Half duplex or full duplex. Duplex mode - Half duplex or full duplex.
Load / Port - Load per port is expressed in a percentage of the ILoad - Intended Load per port is expressed in a percentage of the
medium's maximum intended load possible. The actual transmitted medium's maximum theoretical load, regardless of traffic
frame per second is dependent upon half duplex or full duplex orientation or duplex mode. Certain test configurations will
operation. The test SHOULD be run multiple times with a different theoretically over-subscribe the DUT/SUT.
load per port in each case.
In half duplex mode, exactly half of the intended load SHOULD be
transmitted to each of the ports under test. For example, with a
100% load of 64-byte frames, the intended load for each port under
test is 7440 frames received per second and 7440 frames
transmitted per second (for 10Mbps Ethernet).
In full duplex mode, the entire intended load SHOULD be In half duplex, an ILoad over 50% will over-subscribe the DUT/SUT.
transmitted to each of the ports under test. For example, with a
100% load of 64-byte frames, the intended load for each port under
test is 14880 frames received per second and 14880 frames
transmitted per second (for 10Mbps Ethernet).
Burst Size - The burst size defines the number of frames sent Burst Size - The burst size defines the number of frames sent
back-to-back at the minimum legal IFG (96 bit times) before back-to-back at the minimum legal IFG [4] before pausing
pausing transmission to receive frames. Burst sizes transmission to receive frames. Burst sizes SHOULD vary between 1
SHOULD vary between 1 and 930 frames. A burst size of 1 will and 930 frames. A burst size of 1 will simulate constant load
simulate non-bursty traffic. [1].
Addresses per port - Represents the number of addresses which Addresses per port - Represents the number of addresses which
are being tested for each port. Number of addresses SHOULD be a are being tested for each port. Number of addresses SHOULD be a
binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...). binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
Recommended values are 1, 16 and 256. Recommended value is 1.
Test Duration - Test duration SHOULD be between 1 and 300 seconds. Trial Duration - The recommended Trial Duration is 30 seconds.
RFC 2285 recommends a duration of at least 10 seconds for each Trial duration SHOULD be adjustable between 1 and 300 seconds.
test.
5.1.3 Procedure 5.1.3 Procedure
All ports MUST transmit the exact number of frames. All ports SHOULD All ports on the tester MUST transmit test frames either in a Frame
start transmitting their frames within 1% of the test duration. For Based or Time Based mode (Appendix B). All ports SHOULD start
a test duration of 10 seconds, all ports SHOULD have started transmitting their frames within 1% of the trial duration. For a
transmitting frames with 100 milliseconds of each other. trial duration of 30 seconds, all ports SHOULD have started
transmitting frames within 300 milliseconds of each other.
Each port in the test MUST send frames to all other ports in a Each port in the test MUST send test frames to all other ports in a
round robin type fashion. The following table shows how each port in round robin type fashion. The sequence of addresses MUST NOT change
a test MUST transmit frames to all other ports in the test. In this when backpressure is applied. The following table shows how each
example, there are six ports with 1 address per port: port in a test MUST transmit test frames to all other ports in the
test. In this example, there are six ports with 1 address per port:
Source Port Destination Ports (in order of transmission) Source Port Destination Ports (in order of transmission)
Port #1 2 3 4 5 6 2... Port #1 2 3 4 5 6 2...
Port #2 3 4 5 6 1 3... Port #2 3 4 5 6 1 3...
Port #3 4 5 6 1 2 4... Port #3 4 5 6 1 2 4...
Port #4 5 6 1 2 3 5... Port #4 5 6 1 2 3 5...
Port #5 6 1 2 3 4 6... Port #5 6 1 2 3 4 6...
Port #6 1 2 3 4 5 1... Port #6 1 2 3 4 5 1...
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addresses for each transmit opportunity. This keeps the test balanced addresses for each transmit opportunity. This keeps the test balanced
so that one destination port is not overloaded by the test algorithm so that one destination port is not overloaded by the test algorithm
and all ports are equally and fully loaded throughout the test. Not and all ports are equally and fully loaded throughout the test. Not
following this algorithm exactly will produce inconsistent results. following this algorithm exactly will produce inconsistent results.
For tests using multiple addresses per port, the actual port For tests using multiple addresses per port, the actual port
destinations are the same as described above and the actual destinations are the same as described above and the actual
source/destination address pairs SHOULD be chosen randomly to source/destination address pairs SHOULD be chosen randomly to
exercise the DUT/SUT's ability to perform address lookups. exercise the DUT/SUT's ability to perform address lookups.
For every address, the testing device MUST send learning frames to For every address, learning frames MUST be sent to the DUT/SUT to
allow the DUT/SUT to update its address tables properly. allow the DUT/SUT update its address tables properly.
5.1.4 Measurements 5.1.4 Measurements
Each port should receive the same number of frames that it Each port should receive the same number of test frames that it
transmitted. Each receiving port MUST categorize, then count the transmitted. Each receiving port MUST categorize, then count the
frames into one of two groups: frames into one of two groups:
1.) Received Frames: received frames MUST have the correct 1.) Received Frames: received frames MUST have the correct
destination MAC address and SHOULD match a signature field. destination MAC address and SHOULD match a signature field.
2.) Flood count: defined in RFC 2285 3.8.3. 2.) Flood count [2].
Any frame received which does not have the correct destination
address MUST not be counted as a received frame and SHOULD be counted
as part of a flood count.
Any frame originating from the DUT/SUT MUST not be counted as a Any frame originating from the DUT/SUT (spanning tree, SNMP, RIP,
received frame. Frames originating from the DUT/SUT MAY be counted ...) MUST not be counted as a received frame. Frames originating
as flooded frames or not counted at all. from the DUT/SUT MAY be counted as flooded frames or not counted at
all.
Frame loss rate of the DUT/SUT SHOULD be reported as defined in Frame loss rate of the DUT/SUT SHOULD be reported as defined in
RFC 2544 section 26.3 with the following notes: Frame loss rate section 26.3 [3] with the following notes: Frame loss rate SHOULD be
SHOULD be measured at the end of the test duration. The term "rate", measured at the end of the trail duration. The term "rate", for this
for this measurement only, does not imply the units in the fashion of measurement only, does not imply the units in the fashion of "per
"per seconds." second."
Throughput measurement is defined in RFC 2544. 5.1.4.1 Throughput
Throughput measurement is defined in section 26.1 [3]. A search
algorithm is employed to find the maximum Oload [2] with a zero Frame
loss rate [1]. The algorithm MUST adjust Iload to find the
throughput.
5.1.4.2 Forwarding Rate
Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
of frames per second that the device is observed to successfully of test frames per second that the device is observed to successfully
transmit to the correct destination interface in response to a forward to the correct destination interface in response to a
specified offered load. The offered load MUST also be cited. specified Oload. The Oload MUST also be cited.
Forwarding rate at maximum offered load (FRMOL) MUST be reported Forwarding rate at maximum offered load (FRMOL) MUST be reported
as the number of frames per second that a device can successfully as the number of test frames per second that a device can
transmit to the correct destination interface in response to the successfully transmit to the correct destination interface in
maximum offered load as defined in RFC 2285, section 3.6. The response to the MOL as defined in section 3.6 [2]. The MOL MUST also
maximum offered load MUST also be cited. be cited.
Maximum forwarding rate (MFR) MUST be reported as the highest Maximum forwarding rate (MFR) MUST be reported as the highest
forwarding rate of a DUT/SUT taken from an iterative set of forwarding rate of a DUT/SUT taken from an iterative set of
forwarding rate measurements. The load applied to the device MUST forwarding rate measurements. The iterative set of forwarding rate
also be cited. measurements are made by adjusting Iload. The Oload applied to the
device MUST also be cited.
5.1.5 Reporting format 5.1.5 Reporting format
The results for these tests SHOULD be reported in the form of a The results for these tests SHOULD be reported in the form of a
graph. The x coordinate SHOULD be the frame size, the y coordinate graph. The x coordinate SHOULD be the frame size, the y coordinate
SHOULD be the test results. There SHOULD be at least two lines on SHOULD be the test results. There SHOULD be at least two lines on
the graph, one plotting the theoretical and one plotting the test the graph, one plotting the theoretical and one plotting the test
results. results.
To measure the DUT/SUT's ability to switch traffic while performing To measure the DUT/SUT's ability to switch traffic while performing
many different address lookups, the number of addresses per port many different address lookups, the number of addresses per port
MAY be increased in a series of tests. MAY be increased in a series of tests.
5.2 Partially meshed overloading 5.2 Partially meshed one-to-many/many-to-one
5.2.1 Objective 5.2.1 Objective
To determine the throughput when transmitting from/to multiple ports To determine the throughput when transmitting from/to multiple ports
and to/from one port. As with the fully meshed throughput test, this and to/from one port. As with the fully meshed throughput test, this
test is a measure of the capability of the DUT to switch frames test is a measure of the capability of the DUT to switch frames
without frame loss. Results of this test can be used to determine without frame loss. Results of this test can be used to determine
the ability of the DUT to utilize an Ethernet port when switching the ability of the DUT to utilize an Ethernet port when switching
traffic from multiple Ethernet ports. traffic from multiple Ethernet ports.
5.2.2 Setup Parameters 5.2.2 Setup Parameters
When offering bursty meshed traffic, the following parameters MUST When offering bursty meshed traffic, the following parameters MUST
be defined. Each parameter is configured with the following be defined. Each parameter is configured with the following
considerations. considerations.
Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024, Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
1280 and 1518 bytes, per RFC 2544 section 9. The four CRC bytes 1280 and 1518 bytes, per RFC 2544 section 9 [3]. The four CRC
are included in the frame size specified. bytes are included in the frame size specified.
Traffic Direction - Traffic can be generated in one direction, the Traffic Direction - Traffic can be generated in one direction, the
reverse direction, or both directions. reverse direction, or both directions.
Interframe Gap (IFG) - The IFG between frames inside a burst Interframe Gap (IFG) - The IFG between frames inside a burst
MUST be at the minimum specified by the standard (9.6 us for MUST be at the minimum specified by the standard (9.6 us for
10Mbps Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for 10Mbps Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for
1 Gbps Ethernet). 1 Gbps Ethernet) of the medium being tested.
Interburst Gap (IBG) - This is the interval between bursts of
traffic. Refer to Appendix A, Calculating Interburst Gap, for
the formula used to compute IBG.
Duplex mode - Half duplex or full duplex. Duplex mode - Half duplex or full duplex.
Load / Port - Load per port is expressed in a percentage of the ILoad - Intended Load per port is expressed in a percentage of the
medium's maximum intended load possible. The actual transmitted medium's maximum theoretical load, regardless of traffic
frame per second is dependent upon half duplex or full duplex orientation or duplex mode. Certain test configurations will
operation. The test SHOULD be run multiple times with a different theoretically over-subscribe the DUT/SUT.
load per port in each case.
In half duplex mode, exactly half of the intended load SHOULD be
transmitted to each of the ports under test. For example, with a
100% load of 64-byte frames, the intended load for each port under
test is 7440 frames received per second and 7440 frames
transmitted per second (for 10Mbps Ethernet).
In full duplex mode, the entire intended load SHOULD be In half duplex bidirectional traffic, an ILoad over 50% will over-
transmitted to each of the ports under test. For example, with a subscribe the DUT/SUT.
100% load of 64-byte frames, the intended load for each port under
test is 14880 frames received per second and 14880 frames
transmitted per second (for 10Mbps Ethernet).
Burst Size - The burst size defines the number of frames sent Burst Size - The burst size defines the number of frames sent
back-to-back at the minimum legal IFG (96 bit times) before back-to-back at the minimum legal IFG [4] before pausing
pausing transmission to receive frames. Burst sizes transmission to receive frames. Burst sizes SHOULD vary between 1
SHOULD vary between 1 and 930 frames. A burst size of 1 will and 930 frames. A burst size of 1 will simulate constant load
simulate non-bursty traffic. [1].
Addresses per port - Represents the number of addresses which Addresses per port - Represents the number of addresses which
are being tested for each port. Number of addresses SHOULD be a are being tested for each port. Number of addresses SHOULD be a
binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...). binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
Recommended values are 1, 16 and 256. Recommended value is 1.
Test Duration - Test duration SHOULD be between 1 and 300 seconds. Trial Duration - The recommended Trial Duration is 30 seconds.
RFC 2285 recommends a duration of at least 10 seconds for each Trial duration SHOULD be adjustable between 1 and 300 seconds.
test.
5.2.3 Procedure 5.2.3 Procedure
In this test, each transmitting port MUST transmit the exact number All ports on the tester MUST transmit test frames either in a Frame
of frames. Depending upon traffic direction, some or all of the Based or Time Based mode (Appendix B). Depending upon traffic
ports will be transmitting. direction, some or all of the ports will be transmitting. All ports
SHOULD start transmitting their frames within 1% of the trial
duration. For a trial duration of 30 seconds, all ports SHOULD have
started transmitting frames within 300 milliseconds of each other.
Frames transmitted from the Many Ports MUST be destined to the One Test frames transmitted from the Many Ports MUST be destined to the
port. Frames transmitted from the One Port MUST be destined to the One port. Test frames transmitted from the One Port MUST be destined
Many ports in a round robin type fashion. See section 5.1.3 for a to the Many ports in a round robin type fashion. See section 5.1.3
description of the round robin fashion. for a description of the round robin fashion.
For tests using multiple addresses per port, the actual port For tests using multiple addresses per port, the actual port
destinations are the same as described above and the actual destinations are the same as described above and the actual
source/destination address pairs SHOULD be chosen randomly to source/destination address pairs SHOULD be chosen randomly to
exercise the DUT/SUT's ability to perform address lookups. exercise the DUT/SUT's ability to perform address lookups.
+----------+ +----------+
| | | |
| Many | <-------- | Many | <--------
| | \ | | \
skipping to change at page 9, line 34 skipping to change at page 9, line 13
allow the DUT/SUT to update its address tables properly. allow the DUT/SUT to update its address tables properly.
5.2.4 Measurements 5.2.4 Measurements
Each receiving port MUST categorize, then count the frames into one Each receiving port MUST categorize, then count the frames into one
of two groups: of two groups:
1.) Received Frames: received frames MUST have the correct 1.) Received Frames: received frames MUST have the correct
destination MAC address and SHOULD match a signature field. destination MAC address and SHOULD match a signature field.
2.) Flood count: defined in RFC 2285 3.8.3. 2.) Flood count [2].
Any frame received which does not have the correct destination
address MUST not be counted as a received frame and SHOULD be counted
as part of a flood count.
Any frame originating from the DUT/SUT MUST not be counted as a Any frame originating from the DUT/SUT MUST not be counted as a
received frame. Frames originating from the DUT/SUT MAY be counted received frame. Frames originating from the DUT/SUT MAY be counted
as flooded frames or not counted at all. as flooded frames or not counted at all.
Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
of frames per second that the device is observed to successfully of test frames per second that the device is observed to successfully
transmit to the correct destination interface in response to a transmit to the correct destination interface in response to a
specified offered load. The offered load MUST also be cited. specified Oload. The Oload MUST also be cited.
Forwarding rate at maximum offered load (FRMOL) MUST be reported Forwarding rate at maximum offered load (FRMOL) MUST be reported
as the number of frames per second that a device can successfully as the number of test frames per second that a device can
transmit to the correct destination interface in response to the successfully transmit to the correct destination interface in
maximum offered load as defined in RFC 2285, section 3.6. The response to the MOL as defined in section 3.6 [2]. The MOL MUST also
maximum offered load MUST also be cited. be cited.
Maximum forwarding rate (MFR) MUST be reported as the highest Maximum forwarding rate (MFR) MUST be reported as the highest
forwarding rate of a DUT/SUT taken from an iterative set of forwarding rate of a DUT/SUT taken from an iterative set of
forwarding rate measurements. The load applied to the device MUST forwarding rate measurements. The iterative set of forwarding rate
also be cited. measurements are made by adjusting Iload. The Oload applied to the
device MUST also be cited.
5.2.5 Reporting Format 5.2.5 Reporting Format
The results for these tests SHOULD be reported in the form of a The results for these tests SHOULD be reported in the form of a
graph. The x coordinate SHOULD be the frame size, the y coordinate graph. The x coordinate SHOULD be the frame size, the y coordinate
SHOULD be the test results. There SHOULD be at least two lines on SHOULD be the test results. There SHOULD be at least two lines on
the graph, one plotting the theoretical and one plotting the test the graph, one plotting the theoretical and one plotting the test
results. results.
To measure the DUT/SUT's ability to switch traffic while performing To measure the DUT/SUT's ability to switch traffic while performing
many different address lookups, the number of addresses per port many different address lookups, the number of addresses per port
MAY be increased in a series of tests. MAY be increased in a series of tests.
5.3 Head-of-line blocking 5.3 Partially meshed multiple devices
5.3.1 Objective 5.3.1 Objective
To determine how a DUT handles congestion. Namely, does the device
implement congestion control and does congestion on one port
affect an uncongested port?
5.3.2 Setup Parameters
The following parameters MUST be defined. Each variable is
configured with the following considerations.
Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
1280 and 1518 bytes, per RFC 2544 section 9. The four CRC bytes
are included in the frame size specified.
Duplex mode - Half duplex or full duplex.
Interframe Gap (IFG) - The IFG between frames MUST be at the
minimum specified by the standard (9.6 us for 10Mbps Ethernet,
960 ns for 100Mbps Ethernet, and 96 ns for 1 Gbps Ethernet).
Addresses per port - Represents the number of addresses which
are being tested for each port. Number of addresses SHOULD be a
binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
Recommended values are 1, 16 and 256.
Test Duration - Test duration SHOULD be between 1 and 300 seconds.
RFC 2285 recommends a duration of at least 10 seconds for each
test.
5.3.3 Procedure
This test MUST consist of a multiple of four ports. Four ports are
REQUIRED and MAY be expanded to fully utilize the DUT/SUT in
increments of four. Each group of four will contain a test block
with two of the ports as source transmitters and two of the ports as
receivers. The diagram below depicts the flow of traffic between the
switch ports:
+----------+ 50 % MOL +-------------+
| | ------------------------> | |
| | 50 % MOL | uncongested |
| | --------- | |
+----------+ \ +-------------+
\
\
\
+----------+ \ +-------------+
| | ---------> | |
| | 100 % MOL | congested |
| | ------------------------> | |
+----------+ +-------------+
Both source transmitters MUST transmit the exact number of frames.
The first source MUST transmit frames at the MOL with the destination
address of the two receive ports in an alternating order. The first
frame to the uncongested receive port, second frame to the congested
receive port, then repeat. The second source transmitter MUST
transmit frames at the MOL only to the congested receive port.
Both receive ports SHOULD distinguish between frames originating from
the source ports and frames originating from the DUT/SUT. Only
frames from the source ports SHOULD be counted.
The uncongested receive port should be receiving at a rate of half
the MOL. The number of frames received on the uncongested port
SHOULD be 50% of the frames transmitted by the first source
transmitter. The congested receive port should be receiving at the
MOL. The number of frames received on the congested port should be
between 100% and 150% of the frames transmitted by one source
transmitter.
Frames destined to uncongested ports in a switch device should not
be dropped due to other ports being congested, even if the source
is sending to both the congested and uncongested ports.
5.3.4 Measurements
Any frame received which does not have the correct destination
address MUST not be counted as a received frame and SHOULD be counted
as part of a flood count.
Any frame originating from the DUT/SUT MUST not be counted as a
received frame. Frames originating from the DUT/SUT MAY be counted
as flooded frames or not counted at all.
Frame loss rate of the DUT/SUT's congested and uncongested ports MUST
be reported as defined in RFC 2544 section 26.3 with the following
notes: Frame loss rate SHOULD be measured at the end of the test
duration. The term "rate", for this measurement only, does not imply
the units in the fashion of "per seconds."
Forwarding rate (FR) of the DUT/SUT's congested and uncongested ports
MUST be reported as the number of frames per second that the device
is observed to successfully transmit to the correct destination
interface in response to a specified offered load. The offered load
MUST also be cited.
5.3.5 Reporting format
This test MUST report the frame lost rate at the uncongested port,
the maximum forwarding rate (at 50% offered load) at the uncongested
port, and the frame lost rate at the congested port. This test MAY
report the frame counts transmitted and frame counts received by the
ports.
If the DUT implements a flow control mechanism, an indication of this
is presented by observing no frame loss on the congested port. It
should be noted that this test expects the overall load to the
congested port to be greater than 100%. Therefore if the load is
greater than 100% and no frame loss is detected, then the DUT must be
implementing a flow control mechanism. The type of flow control
mechanism used is beyond the scope of this memo.
If there is frame loss at the uncongested port, "Head of Line"
blocking exists. The DUT cannot forward the amount of traffic to the
congested port and as a result it is also losing frames destined to
the uncongested port.
It should be noted that some DUTs may not be able to handle the 100%
load presented at the input port. In this case, there may be frame
loss reported at the uncongested port which is due to the load at the
input port rather than the congested port's load.
If the uncongested frame loss is reported as zero, but the maximum
forwarding rate is less than 7440 (for 10Mbps Ethernet), then this
may be an indication of congestion control being enforced by the DUT.
In this case, the congestion control is affecting the throughput of
the uncongested port.
If no congestion control is detected, the expected percentage frame
loss for the congested port is 33% at 150% overload. It is receiving
100% load from 1 port, and 50% from another, and can only get 100%
possible throughput, therefore having a frame loss rate of 33%
(150%-50%/150%).
5.4 Partially Meshed Multiple Devices
5.4.1 Objective
To determine the throughput, frame loss and forwarding rates of two To determine the throughput, frame loss and forwarding rates of two
switching devices equipped with multiple Ethernet ports and one high switching devices equipped with multiple ports and one high speed
speed backbone uplink (Gigabit Ethernet, ATM, SONET). backbone uplink (Gigabit Ethernet, ATM, SONET).
5.4.2 Setup Parameters 5.3.2 Setup Parameters
When offering bursty partially meshed traffic, the following When offering bursty partially meshed traffic, the following
parameters MUST be defined. Each variable is configured with the parameters MUST be defined. Each variable is configured with the
following considerations. following considerations.
Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024, Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
1280 and 1518 bytes, per RFC 2544 section 9. The four CRC bytes 1280 and 1518 bytes, per RFC 2544 section 9 [3]. The four CRC
are included in the frame size specified. bytes are included in the frame size specified.
Interframe Gap (IFG) - The IFG between frames inside a burst Interframe Gap (IFG) - The IFG between frames inside a burst
MUST be at the minimum specified by the standard (9.6 us for MUST be at the minimum specified by the standard (9.6 us for
10Mbps Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for 10Mbps Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for
1 Gbps Ethernet). 1 Gbps Ethernet) of the medium being tested.
Interburst Gap (IBG) - This is the interval between bursts of
traffic. Refer to Appendix A, Calculating Interburst Gap, for
the formula used to compute IBG.
Duplex mode - Half duplex or full duplex. Duplex mode - Half duplex or full duplex.
Load / Port - Load per port is expressed in a percentage of the ILoad - Intended Load per port is expressed in a percentage of the
medium's maximum intended load possible. The actual transmitted medium's maximum theoretical load, regardless of traffic
frame per second is dependent upon half duplex or full duplex orientation or duplex mode. Certain test configurations will
operation. The test SHOULD be run multiple times with a different theoretically over-subscribe the DUT/SUT.
load per port in each case.
In half duplex mode, exactly half of the intended load SHOULD be
transmitted to each of the ports under test. For example, with a
100% load of 64-byte frames, the intended load for each port under
test is 7440 frames received per second and 7440 frames
transmitted per second (for 10Mbps Ethernet).
In full duplex mode, the entire intended load SHOULD be In half duplex, an ILoad over 50% will over-subscribe the DUT/SUT.
transmitted to each of the ports under test. For example, with a
100% load of 64-byte frames, the intended load for each port under
test is 14880 frames received per second and 14880 frames
transmitted per second (for 10Mbps Ethernet).
Burst Size - The burst size defines the number of frames sent Burst Size - The burst size defines the number of frames sent
back-to-back at the minimum legal IFG (96 bit times) before back-to-back at the minimum legal IFG [4] before pausing
pausing transmission to receive frames. Burst sizes transmission to receive frames. Burst sizes SHOULD vary between 1
SHOULD vary between 1 and 930 frames. and 930 frames. A burst size of 1 will simulate constant load
[1].
Addresses per port - Represents the number of addresses which Addresses per port - Represents the number of addresses which
are being tested for each port. Number of addresses SHOULD be a are being tested for each port. Number of addresses SHOULD be a
binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...). binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
Recommended values are 1, 16 and 256. Recommended value is 1.
Test Duration - Test duration SHOULD be between 1 and 300 seconds. Trial Duration - The recommended Trial Duration is 30 seconds.
RFC 2285 recommends a duration of at least 10 seconds for each Trial duration SHOULD be adjustable between 1 and 300 seconds.
test.
Local Traffic - A Boolean value of ON or OFF. The frame Local Traffic - A Boolean value of ON or OFF. The frame
sequence sequence
algorithm MAY be altered to remove local traffic. With local algorithm MAY be altered to remove local traffic. With local
traffic ON, the algorithm is exactly the same as a fully meshed traffic ON, the algorithm is exactly the same as a fully meshed
throughput. With local traffic OFF, the port sends frames to all throughput. With local traffic OFF, the port sends frames to all
other ports on the other side of the backbone uplink in a round other ports on the other side of the backbone uplink in a round
robin type fashion. robin type fashion.
5.4.3 Procedure 5.3.3 Procedure
All ports MUST transmit the exact number of frames. All ports SHOULD All ports on the tester MUST transmit test frames either in a Frame
start transmitting their frames within 1% of the test duration. For Based or Time Based mode (Appendix B). All ports SHOULD start
a test duration of 10 seconds, all ports SHOULD have started transmitting their frames within 1% of the trial duration. For a
transmitting frames with 100 milliseconds of each other. trial duration of 30 seconds, all ports SHOULD have started
transmitting frames with 300 milliseconds of each other.
Each port in the test MUST send frames to all other ports in a Each port in the test MUST send test frames to all other ports in a
round robin type fashion as defined in section 5.1. Local traffic round robin type fashion as defined in section 5.1.3. Local traffic
MAY be removed from the round robin list in order to send the entire MAY be removed from the round robin list in order to send the entire
load across the backbone uplink. load across the backbone uplink.
For tests using multiple addresses per port, the actual port For tests using multiple addresses per port, the actual port
destinations are the same as described above and the actual destinations are the same as described above and the actual
source/destination address pairs SHOULD be chosen randomly to source/destination address pairs SHOULD be chosen randomly to
exercise the DUT/SUT's ability to perform address lookups. exercise the DUT/SUT's ability to perform address lookups.
For every address, the testing device MUST send learning frames to For every address, the testing device MUST send learning frames to
allow the DUT/SUT to update its address tables properly. allow the DUT/SUT to update its address tables properly.
To measure the DUT/SUT's ability to switch traffic while performing To measure the DUT/SUT's ability to switch traffic while performing
many different address lookups, the number of addresses per port many different address lookups, the number of addresses per port
MAY be increased in a series of tests. MAY be increased in a series of tests.
5.4.4 Measurements 5.3.4 Measurements
Each port should receive the same amount of frames that is Each receiving port MUST categorize, then count the frames into one
transmitted. Each receiving port MUST categorize, then count the of two groups:
frames into one of two groups:
1.) Received frames MUST have the correct destination MAC address 1.) Received frames MUST have the correct destination MAC address
and SHOULD match a signature field. and SHOULD match a signature field.
2.) Flood count (defined in RFC 2285 3.8.3). 2.) Flood count [2].
Any frame received which does not have the correct destination
address MUST not be counted as a received frame and SHOULD be counted
as part of a flood count.
Any frame originating from the DUT/SUT MUST not be counted as a Any frame originating from the DUT/SUT MUST not be counted as a
received frame. Frames originating from the DUT/SUT MAY be counted received frame. Frames originating from the DUT/SUT MAY be counted
as flooded frames or not counted at all. as flooded frames or not counted at all.
Frame loss rate of the DUT/SUT SHOULD be reported as defined in Frame loss rate of the DUT/SUT SHOULD be reported as defined in
RFC 2544 section 26.3 with the following notes: Frame loss rate section 26.3 [3] with the following notes: Frame loss rate SHOULD be
SHOULD be measured at the end of the test duration. The term "rate", measured at the end of the trial duration. The term "rate", for this
for this measurement only, does not imply the units in the fashion of measurement only, does not imply the units in the fashion of "per
"per seconds." second."
5.3.4.1 Throughput
Throughput measurement is defined in section 26.1 [3]. A search
algorithm is employed to find the maximum Oload [2] with a zero Frame
loss rate [1]. The algorithm MUST adjust Iload to find the
throughput.
5.3.4.2 Forwarding rate
Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
of frames per second that the device is observed to successfully of test frames per second that the device is observed to successfully
transmit to the correct destination interface in response to a forward to the correct destination interface in response to a
specified offered load. The offered load MUST also be cited. specified Oload. The Oload MUST also be cited.
Forwarding rate at maximum offered load (FRMOL) MUST be reported Forwarding rate at maximum offered load (FRMOL) MUST be reported
as the number of frames per second that a device can successfully as the number of test frames per second that a device can
transmit to the correct destination interface in response to the successfully transmit to the correct destination interface in
maximum offered load as defined in RFC 2285, section 3.6. The response to the MOL as defined in section 3.6 [2]. The MOL MUST also
maximum offered load MUST also be cited. be cited.
Maximum forwarding rate (MFR) MUST be reported as the highest Maximum forwarding rate (MFR) MUST be reported as the highest
forwarding rate of a DUT/SUT taken from an iterative set of forwarding rate of a DUT/SUT taken from an iterative set of
forwarding rate measurements. The load applied to the device MUST forwarding rate measurements. The iterative set of forwarding rate
also be cited. measurements are made by adjusting Iload. The Oload applied to the
device MUST also be cited.
5.4.5 Reporting format 5.3.5 Reporting format
The results for these tests SHOULD be reported in the form of a The results for these tests SHOULD be reported in the form of a
graph. The x coordinate SHOULD be the frame size, the y coordinate graph. The x coordinate SHOULD be the frame size, the y coordinate
SHOULD be the test results. There SHOULD be at least two lines on SHOULD be the test results. There SHOULD be at least two lines on
the graph, one plotting the theoretical and one plotting the test the graph, one plotting the theoretical and one plotting the test
results. results.
To measure the DUT/SUT's ability to switch traffic while performing To measure the DUT/SUT's ability to switch traffic while performing
many different address lookups, the number of addresses per port many different address lookups, the number of addresses per port
MAY be increased in a series of tests. MAY be increased in a series of tests.
5.5 Multiple streams of unidirectional traffic 5.4 Partially meshed unidirectional traffic
5.5.1 Objective 5.4.1 Objective
To determine the throughput of the DUT/SUT when presented multiple To determine the throughput of the DUT/SUT when presented multiple
streams of unidirectional traffic with half of the ports on the streams of unidirectional traffic with half of the ports on the
DUT/SUT are receiving frames destined to the other half of the DUT/SUT are transmitting frames destined to the other half of the
ports. ports.
5.1.2 Setup Parameters 5.4.2 Setup Parameters
The following parameters MUST be defined. Each variable is The following parameters MUST be defined. Each variable is
configured with the following considerations. configured with the following considerations.
Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024, Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
1280 and 1518 bytes, per RFC 2544 section 9. The four CRC bytes 1280 and 1518 bytes, per RFC 2544 section 9 [3]. The four CRC
are included in the frame size specified. bytes are included in the frame size specified.
Interframe Gap (IFG) - The IFG between frames inside a burst
MUST be at the minimum specified by the standard (9.6 us for
10Mbps Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for
1 Gbps Ethernet) of the medium being tested.
Duplex mode - Half duplex or full duplex. Duplex mode - Half duplex or full duplex.
Load / Port - Load per port is expressed in a percentage of the ILoad - Intended Load per port is expressed in a percentage of the
medium's maximum intended load possible. The actual transmitted medium's maximum theoretical load, regardless of traffic
frame per second is dependent upon half duplex or full duplex orientation or duplex mode. Certain test configurations will
operation. The test SHOULD be run multiple times with a different theoretically over-subscribe the DUT/SUT.
load per port in each case.
In half duplex mode, exactly half of the intended load SHOULD be ILoad will not over-subscribe the DUT/SUT in this test.
transmitted to each of the ports under test. For example, with a
100% load of 64-byte frames, the intended load for each port under
test is 7440 frames received per second and 7440 frames
transmitted per second (for 10Mbps Ethernet).
In full duplex mode, the entire intended load SHOULD be Burst Size - The burst size defines the number of frames sent
transmitted to each of the ports under test. For example, with a back-to-back at the minimum legal IFG [4] before pausing
100% load of 64-byte frames, the intended load for each port under transmission to receive frames. Burst sizes SHOULD vary between 1
test is 14880 frames received per second and 14880 frames and 930 frames. A burst size of 1 will simulate constant load
transmitted per second (for 10Mbps Ethernet). [1].
Addresses per port - Represents the number of addresses which Addresses per port - Represents the number of addresses which
are being tested for each port. Number of addresses SHOULD be a are being tested for each port. Number of addresses SHOULD be a
binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...). binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
Recommended values are 1, 16 and 256. Recommended value is 1.
Test Duration - Test duration SHOULD be between 1 and 300 seconds. Trial Duration - The recommended Trial Duration is 30 seconds.
RFC 2285 recommends a duration of at least 10 seconds for each Trial duration SHOULD be adjustable between 1 and 300 seconds.
test.
5.5.3 Procedure 5.4.3 Procedure
Ports do not send and receive frames simultaneously. As a Ports do not send and receive test frames simultaneously. As a
consequence, there should be no collisions unless the DUT is consequence, there should be no collisions unless the DUT is
misforwarding frames, generating flooded or Spanning-Tree frames or misforwarding frames, generating flooded or Spanning-Tree frames or
is enabling some flow control mechanism. Ports used for this test is enabling some flow control mechanism. Ports used for this test
are either transmitting or receiving, but not both. Those ports which are either transmitting or receiving, but not both. Those ports which
are transmitting send frames destined to addresses corresponding to are transmitting send test frames destined to addresses corresponding
each of the ports receiving. This creates a unidirectional mesh of to each of the ports receiving. This creates a unidirectional mesh
traffic. of traffic.
All ports MUST transmit the exact number of frames. All ports SHOULD All ports on the tester MUST transmit test frames either in a Frame
start transmitting their frames within 1% of the test duration. For Based or Time Based mode (Appendix B). All ports SHOULD start
a test duration of 10 seconds, all ports SHOULD have started transmitting their frames within 1% of the trial duration. For a
transmitting frames with 100 milliseconds of each other. trial duration of 30 seconds, all ports SHOULD have started
transmitting frames with 300 milliseconds of each other.
Each transmitting port in the test MUST send frames to all receiving Each transmitting port in the test MUST send frames to all receiving
ports in a round robin type fashion. The following table shows how ports in a round robin type fashion. The sequence of addresses MUST
each port in a test MUST transmit frames to all other ports in the NOT change when backpressure is applied. The following table shows
test. In this 8 port example, port 1 through 4 are transmitting and how each port in a test MUST transmit test frames to all other ports
ports 5 through 8 are receiving; each with 1 address per port: in the test. In this 8 port example, port 1 through 4 are
transmitting and ports 5 through 8 are receiving; each with 1 address
per port:
Source Port, then Destination Ports (in order of transmission) Source Port, then Destination Ports (in order of transmission)
Port #1 5 6 7 8 5 6... Port #1 5 6 7 8 5 6...
Port #2 6 7 8 5 6 7... Port #2 6 7 8 5 6 7...
Port #3 7 8 5 6 7 8... Port #3 7 8 5 6 7 8...
Port #4 8 5 6 7 8 5... Port #4 8 5 6 7 8 5...
As shown in the table, there is an equal distribution of destination As shown in the table, there is an equal distribution of destination
addresses for each transmit opportunity. This keeps the test balanced addresses for each transmit opportunity. This keeps the test balanced
skipping to change at page 17, line 38 skipping to change at page 14, line 52
results. results.
For tests using multiple addresses per port, the actual port For tests using multiple addresses per port, the actual port
destinations are the same as described above and the actual destinations are the same as described above and the actual
source/destination address pairs SHOULD be chosen randomly to source/destination address pairs SHOULD be chosen randomly to
exercise the DUT/SUT's ability to perform address lookups. exercise the DUT/SUT's ability to perform address lookups.
For every address, the testing device MUST send learning frames to For every address, the testing device MUST send learning frames to
allow the DUT/SUT to load its address tables properly. The address allow the DUT/SUT to load its address tables properly. The address
table's aging time SHOULD be set sufficiently longer than the table's aging time SHOULD be set sufficiently longer than the
learning time and test duration time combined. If the address table learning time and trial duration time combined. If the address table
ages out during the test, the results will show a lower performing ages out during the test, the results will show a lower performing
DUT/SUT. DUT/SUT.
To measure the DUT/SUT's ability to switch traffic while performing To measure the DUT/SUT's ability to switch traffic while performing
many different address lookups, the number of addresses per port many different address lookups, the number of addresses per port
MAY be increased in a series of tests. MAY be increased in a series of tests.
5.5.4 Measurements 5.4.4 Measurements
Each port should receive the same number of frames that it Each receiving port MUST categorize, then count the frames into one
transmitted. Each receiving port MUST categorize, then count the of two groups:
frames into one of two groups:
1.) Received Frames: received frames MUST have the correct 1.) Received Frames: received frames MUST have the correct
destination MAC address and SHOULD match a signature field. destination MAC address and SHOULD match a signature field.
2.) Flood count: defined in RFC 2285 3.8.3. 2.) Flood count [2].
Any frame received which does not have the correct destination
address MUST not be counted as a received frame and SHOULD be counted
as part of a flood count.
Any frame originating from the DUT/SUT MUST not be counted as a Any frame originating from the DUT/SUT MUST not be counted as a
received frame. Frames originating from the DUT/SUT MAY be counted received frame. Frames originating from the DUT/SUT MAY be counted
as flooded frames or not counted at all. as flooded frames or not counted at all.
Frame loss rate of the DUT/SUT SHOULD be reported as defined in Frame loss rate of the DUT/SUT SHOULD be reported as defined in
RFC 2544 section 26.3 with the following notes: Frame loss rate section 26.3 [3] with the following notes: Frame loss rate SHOULD be
SHOULD be measured at the end of the test duration. The term "rate", measured at the end of the trial duration. The term "rate", for this
for this measurement only, does not imply the units in the fashion of measurement only, does not imply the units in the fashion of "per
"per seconds." second."
5.4.4.1 Throughput
Throughput measurement is defined in section 26.1 [3]. A search
algorithm is employed to find the maximum Oload [2] with a zero Frame
loss rate [1]. The algorithm MUST adjust Iload to find the
throughput.
5.4.4.2 Forwarding rate
Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
of frames per second that the device is observed to successfully of test frames per second that the device is observed to successfully
transmit to the correct destination interface in response to a forward to the correct destination interface in response to a
specified offered load. The offered load MUST also be cited. specified Oload. The Oload MUST also be cited.
Forwarding rate at maximum offered load (FRMOL) MUST be reported Forwarding rate at maximum offered load (FRMOL) MUST be reported
as the number of frames per second that a device can successfully as the number of test frames per second that a device can
transmit to the correct destination interface in response to the successfully transmit to the correct destination interface in
maximum offered load as defined in RFC 2285, section 3.6. The response to the MOL as defined in section 3.6 [2]. The MOL MUST also
maximum offered load MUST also be cited. be cited.
Maximum forwarding rate (MFR) MUST be reported as the highest Maximum forwarding rate (MFR) MUST be reported as the highest
forwarding rate of a DUT/SUT taken from an iterative set of forwarding rate of a DUT/SUT taken from an iterative set of
forwarding rate measurements. The load applied to the device MUST forwarding rate measurements. The iterative set of forwarding rate
also be cited. measurements are made by adjusting Iload. The Oload applied to the
device MUST also be cited.
5.1.5 Reporting format 5.4.5 Reporting format
The results for these tests SHOULD be reported in the form of a The results for these tests SHOULD be reported in the form of a
graph. The x coordinate SHOULD be the frame size, the y coordinate graph. The x coordinate SHOULD be the frame size, the y coordinate
SHOULD be the test results. There SHOULD be at least two lines on SHOULD be the test results. There SHOULD be at least two lines on
the graph, one plotting the theoretical and one plotting the test the graph, one plotting the theoretical and one plotting the test
results. results.
To measure the DUT/SUT's ability to switch traffic while performing To measure the DUT/SUT's ability to switch traffic while performing
many different address lookups, the number of addresses per port many different address lookups, the number of addresses per port
MAY be increased in a series of tests. MAY be increased in a series of tests.
5.6 Filter illegal frames 5.5 Congestion Control
5.6.1 Objective 5.5.1 Objective
The objective of the filter illegal frame test is to determine To determine how a DUT handles congestion. Does the device implement
the behavior of the DUT under errors or abnormal frame conditions. back pressure (congestion control) and does congestion on one port
The results of the test indicate if the DUT/SUT filters the errors, affect an uncongested port. This procedure determines if Head of
or simply propagates the errored frames along to the destination. Line Blocking and/or Backpressure are present.
5.1.2 Setup Parameters 5.5.2 Setup Parameters
The following parameters MUST be defined. Each variable is The following parameters MUST be defined. Each variable is
configured with the following considerations. configured with the following considerations.
Load / Port - Load per port is expressed in a percentage of the Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
medium's maximum intended load possible. The actual transmitted 1280 and 1518 bytes, per RFC 2544 section 9 [3]. The four CRC
frame per second is dependent upon half duplex or full duplex bytes are included in the frame size specified.
operation. The test SHOULD be run multiple times with a different
load per port in each case.
Test Duration - Test duration SHOULD be between 1 and 300 seconds. Interframe Gap (IFG) - The IFG between frames inside a burst
RFC 2285 recommends a duration of at least 10 seconds for each MUST be at the minimum specified by the standard (9.6 us for
test. 10Mbps Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for
1 Gbps Ethernet) of the medium being tested.
5.6.3 Procedure Duplex mode - Half duplex or full duplex.
Each of the illegal frames for Ethernet MUST be checked: Addresses per port - Represents the number of addresses which
are being tested for each port. Number of addresses SHOULD be a
binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
Recommended value is 1.
Oversize - The DUT/SUT MAY filter frames larger than 1518 bytes Trial Duration - The recommended Trial Duration is 30 seconds.
from being propagated through the DUT/SUT (ISO 8802-3 4.2.4.2.1). Trial duration SHOULD be adjustable between 1 and 300 seconds.
Oversized frames transmitted to the DUT/SUT should not appear as
receive frames or as error frames on any port. DUT/SUT supporting
tagged Frames MAY forward frames up to and including 1522 bytes
long (IEEE 802.3ac 4.2.4.2.1).
Undersize - The DUT/SUT MUST filter frames less than 64 bytes from 5.5.3 Procedure
being propagated through the DUT/SUT (per ISO 8802-3 4.2.4.2.2).
Undersized frames (or collision fragments) transmitted to the DUT/SUT
MUST not appear as receive frames or as error frames on another port.
CRC Errors - The DUT/SUT MUST filter frames that fail the Frame Check This test MUST consist of a multiple of four ports. Four ports are
Sequence Validation (ISO 8802-3 4.2.4.1.2) from being propagated REQUIRED and MAY be expanded to fully utilize the DUT/SUT in
through the DUT/SUT. Frames with an invalid CRC transmitted to the increments of four. Each group of four will contain a test block
DUT/SUT should not appear as receive frames or as error frames on with two of the ports as source transmitters and two of the ports as
another port. receivers. The diagram below depicts the flow of traffic between the
switch ports:
Dribble Bit Errors - The DUT/SUT MUST correct and forward frames +----------+ 50 % MOL +-------------+
containing dribbling bits. Frames transmitted to the DUT/SUT that do | | ------------------------> | |
not end in an octet boundary but contain a valid frame check sequence | | 50 % MOL | uncongested |
MUST be accepted by the DUT/SUT (ISO 8802-3 4.2.4.2.1) and forwarded | | --------- | |
to the correct receive port with the frame ending in an octet +----------+ \ +-------------+
boundary (ISO 8802-3 3.4). \
\
\
+----------+ \ +-------------+
| | ---------> | |
| | 100 % MOL | congested |
| | ------------------------> | |
+----------+ +-------------+
Alignment Errors - The DUT/SUT MUST filter frames than fail the Frame Both source transmitters MUST transmit the exact number of test
Check Sequence Validation AND do not end in an octet boundary. This frames. The first source MUST transmit test frames at the MOL with
is a combination of a CRC error and a Dribble Bit error. When both the destination address of the two receive ports in an alternating
errors are occurring in the same frame, the DUT/SUT MUST determine order. The first test frame to the uncongested receive port, second
the CRC error takes precedence and filters the frame (ISO 8802-3 test frame to the congested receive port, then repeat. The second
4.2.4.1.2) from being propagated. source transmitter MUST transmit test frames at the MOL only to the
congested receive port.
5.7 Broadcast frame handling and latency test Both receive ports SHOULD distinguish between test frames originating
from the source ports and frames originating from the DUT/SUT. Only
test frames from the source ports SHOULD be counted.
5.7.1 Objective The uncongested receive port should be receiving at a rate of half
the MOL. The number of test frames received on the uncongested port
SHOULD be 50% of the test frames transmitted by the first source
transmitter. The congested receive port should be receiving at the
MOL. The number of test frames received on the congested port should
be between 100% and 150% of the test frames transmitted by one source
transmitter.
The objective of the Broadcast Frame Handling and Latency Test is to Test frames destined to uncongested ports in a switch device should
determine the throughput and latency of the DUT when handling not be dropped due to other ports being congested, even if the source
broadcast traffic. The ability to forward broadcast frames will is sending to both the congested and uncongested ports.
depend on special features built into the device for that purpose.
It is therefore necessary to determine the ability of switches to
handle broadcast frames, since there may be many different ways of
implementing such a feature.
5.7.2 Setup Parameters 5.5.4 Measurements
The following parameters MUST be defined. Each variable is Any frame received which does not have the correct destination
configured with the following considerations. address MUST not be counted as a received frame and SHOULD be counted
as part of a flood count.
Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024, Any frame originating from the DUT/SUT MUST not be counted as a
1280 and 1518 bytes, per RFC 2544 section 9. The four CRC bytes received frame. Frames originating from the DUT/SUT MAY be counted
are included in the frame size specified. as flooded frames or not counted at all.
Duplex mode - Half duplex or full duplex. Frame loss rate of the DUT/SUT's congested and uncongested ports MUST
be reported as defined in section 26.3 [3] with the following notes:
Frame loss rate SHOULD be measured at the end of the trial duration.
The term "rate", for this measurement only, does not imply the units
in the fashion of "per second."
Load / Port - Load per port is expressed in a percentage of the Offered Load to the DUT/SUT MUST be reported as the number of test
medium's maximum intended load possible. The actual transmitted frames per second that the DUT/SUT observed to accept. This may be
frame per second is dependent upon half duplex or full duplex different that the MOL.
operation. The test SHOULD be run multiple times with a different
load per port in each case.
In half duplex mode, exactly half of the intended load SHOULD be Forwarding rate (FR) of the DUT/SUT's congested and uncongested ports
transmitted to each of the ports under test. For example, with a MUST be reported as the number of test frames per second that the
100% load of 64-byte frames, the intended load for each port under device is observed to successfully transmit to the correct
test is 7440 frames received per second and 7440 frames destination interface in response to a specified offered load. The
transmitted per second (for 10Mbps Ethernet). offered load MUST also be cited.
In full duplex mode, the entire intended load SHOULD be 5.5.5 Reporting format
transmitted to each of the ports under test. For example, with a
100% load of 64-byte frames, the intended load for each port under
test is 14880 frames received per second and 14880 frames
transmitted per second (for 10Mbps Ethernet).
Test Duration - Test duration SHOULD be between 1 and 300 seconds. This test MUST report the frame lost rate at the uncongested port,
RFC 2285 recommends a duration of at least 10 seconds for each the maximum forwarding rate (at 50% offered load) at the uncongested
test. port, and the frame lost rate at the congested port. This test MAY
report the frame counts transmitted and frame counts received by the
DUT/SUT.
5.7.3 Procedure 5.5.5.1 HOLB
For this test, there are two parts to be run. If there is frame loss at the uncongested port, "Head of Line"
blocking is present. The DUT cannot forward the amount of traffic to
the congested port and as a result it is also losing frames destined
to the uncongested port.
Broadcast Frame Throughput - This portion of the test uses a single 5.5.5.2 Back Pressure
source test port to transmit frames with a broadcast address using
the frame specified in RFC 2544. Selected receive ports then
measure the forwarding rate and Frame loss rate.
Broadcast Frame Latency - This test uses the same setup as the If there is no frame loss on the congested port, then backpressure
Broadcast Frame throughput, but instead of a large stream of frames is present. It should be noted that this test expects the overall
being sent, only one frame is sent and the latency to each of the load to the congested port to be greater than 100%. Therefore if the
receive ports are measured in seconds. load is greater than 100% and no frame loss is detected, then the DUT
must be implementing a flow control mechanism. The type of flow
control mechanism used is beyond the scope of this memo.
5.7.4 Measurements It should be noted that some DUTs may not be able to handle the 100%
load presented at the input port. In this case, there may be frame
loss reported at the uncongested port which is due to the load at the
input port rather than the congested port's load.
Frame loss rate of the DUT/SUT SHOULD be reported as defined in If the uncongested frame loss is reported as zero, but the maximum
RFC 2544 section 26.3 with the following notes: Frame loss rate forwarding rate is less than 7440 (for 10Mbps Ethernet), then this
SHOULD be measured at the end of the test duration. The term "rate", may be an indication of congestion control being enforced by the DUT.
for this measurement only, does not imply the units in the fashion of In this case, the congestion control is affecting the throughput of
"per seconds." the uncongested port.
Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number If no congestion control is detected, the expected percentage frame
of frames per second that the device is observed to successfully loss for the congested port is 33% at 150% overload. It is receiving
transmit to the correct destination interface in response to a 100% load from 1 port, and 50% from another, and can only get 100%
specified offered load. The offered load MUST also be cited. possible throughput, therefore having a frame loss rate of 33%
(150%-50%/150%).
5.8 Maximum forwarding rate and minimum interframe gap 5.6 Forward Pressure and Maximum Forwarding Rate
5.8.1 Objective 5.6.1 Objective
The objective of the Maximum forwarding rate test is to find the The Forward Pressure test overloads a DUT/SUT port and measures the
peak value of the Forwarding Rate when the Offered Load is varied output for forward pressure [2]. If the DUT/SUT transmits frames
between the throughput (RFC 1242) and the Maximum Offered Load with an interframe gap less than 96 bits (section 4.2.3.2.2 [4]),
(RFC 2285). then forward pressure is detected.
The Minimum Interframe gap Test overloads a DUT/SUT port and measure The objective of the Maximum Forwarding Rate test is to measure the
the output for forward pressure. If the DUT/SUT transmits frames peak value of the Forwarding Rate when the Offered Load is varied
with an interframe gap less than 96 bits (ISO 8802-3 4.2.3.2.2), then between the throughput [1] and the Maximum Offered Load [2].
forward pressure is detected.
5.8.2 Setup Parameters 5.6.2 Setup Parameters
The following parameters MUST be defined. Each variable is The following parameters MUST be defined. Each variable is
configured with the following considerations. configured with the following considerations.
Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024, Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
1280 and 1518 bytes, per RFC 2544 section 9. The four CRC bytes 1280 and 1518 bytes, per RFC 2544 section 9 [3]. The four CRC
are included in the frame size specified. bytes are included in the frame size specified.
Duplex mode - Half duplex or full duplex. Duplex mode - Half duplex or full duplex.
Test Duration - Test duration SHOULD be between 1 and 300 seconds. Trial Duration - The recommended Trial Duration is 30 seconds.
RFC 2285 recommends a duration of at least 10 seconds for each Trial duration SHOULD be adjustable between 1 and 300 seconds.
test.
Step Size - The minimum incremental resolution that the Offered Step Size - The minimum incremental resolution that the Iload
Load (OL) will be incremented in frames per second. The smaller will
the step size, the more accurate the measurement and the more be incremented in frames per second. The smaller the step size,
iterations required. As the Offered Load approaches the Maximum the more accurate the measurement and the more iterations
Offered Load, the minimum step size will increase because of gap required. As the Iload approaches the MOL, the minimum step size
resolution on the testing device. will increase because of gap resolution on the testing device.
5.8.3 Procedure 5.6.3 Procedure
If the throughput and the Maximum Offered Load are the same, then 5.6.3.1 Maximum forwarding rate
Maximum Forwarding rate is equal to the Maximum Offered Load.
This test SHOULD at a minimum be performed in a two-port If the Throughput [1] and the MOL [2] are the same, then MFR [2]
configuration as described below. Learning frames MUST be sent to is equal to the MOL [2].
allow the DUT/SUT to update its address tables properly.
The first port (port 1) device transmits frames at the Offered Load This test MUST at a minimum be performed in a two-port configuration
to the DUT/SUT. A second port (port 2) receives frames from the as described below. Learning frames MUST be sent to allow the
DUT/SUT and measures the Forwarding Rate. DUT/SUT to update its address tables properly.
The Offered Load is incremented for each Step Size to find the Test frames are transmitted to the first port (port 1) of the DUT/SUT
Maximum Forwarding Rate. The algorithm for the test is as follows: at the Iload. The FR [2] on the second port (port 2) of the DUT/SUT
is measured. The Iload is incremented for each Step Size to find the
MFR. The algorithm for the test is as follows:
CONSTANT CONSTANT
MOL = ... frames/sec; {Maximum Offered Load} MOL = ... frames/sec; {Maximum Offered Load}
VARIABLE VARIABLE
MFR := 0 frames/sec; {Maximum Forwarding Rate} MFR := 0 frames/sec; {Maximum Forwarding Rate}
OLOAD := starting throughput in frames/sec; {offered load} ILOAD := starting throughput in frames/sec; {offered load}
STEP := ... frames/sec; {Step Size} STEP := ... frames/sec; {Step Size}
BEGIN BEGIN
OLOAD := OLOAD - STEP; ILOAD := ILOAD - STEP;
DO DO
BEGIN BEGIN
OLOAD := OLOAD + STEP ILOAD := ILOAD + STEP
IF (OLOAD > MOL) THEN IF (ILOAD > MOL) THEN
BEGIN BEGIN
OLOAD := MOL ILOAD := MOL
END END
AddressLearning; {Port 2 broadcast frame with its source AddressLearning; {Port 2 broadcasts with its source address}
address} Transmit(ILOAD); {Port 1 sends frames to Port 2 at Offered load}
Transmit(OLOAD); {Port 1 sends frames to Port 2 at Offered load}
IF (Port 2 Forwarding Rate > MFR) THEN IF (Port 2 Forwarding Rate > MFR) THEN
BEGIN BEGIN
MFR := Port 2 Forwarding Rate; {A higher value than before} MFR := Port 2 Forwarding Rate; {A higher value than before}
END END
END END
WHILE (OLOAD >= MOL); {MFR equals Maximum Forwarding Rate} WHILE (ILOAD < MOL); {ILOAD has reached the MOL value}
DONE DONE
5.6.3.2 Minimum Interframe Gap
The Minimum Interframe gap test SHOULD, at a minimum, be performed in The Minimum Interframe gap test SHOULD, at a minimum, be performed in
a two-port configuration as described below. Learning frames MUST be a two-port configuration as described below. Learning frames MUST be
sent to allow the DUT/SUT to update its address tables properly. sent to allow the DUT/SUT to update its address tables properly.
The first port (port 1) device transmits frames with an interframe Test frames SHOULD be transmitted to the first port (port 1) of the
gap of 88 bits to the DUT/SUT. This will apply forward pressure to DUT/SUT with an interframe gap of 88 bits. This will apply forward
the DUT/SUT and overload it at a rate of one byte per frame. The pressure to the DUT/SUT and overload it at a rate of one byte per
frames MUST be constructed with a source address of port 1 and a frame. The test frames MUST be constructed with a source address of
destination address of port 2. port 1 and a destination address of port 2.
A second port (port 2) receives frames from the DUT/SUT and measures The FR on the second port (port 2) of the DUT/SUT is measured. The
the Forwarding Rate. The measured Forwarding Rate SHOULD not exceed measured Forwarding Rate should not exceed the medium's maximum
the medium's maximum theoretical utilization. theoretical utilization (MOL).
5.8.4 Measurements 5.6.4 Measurements
Port 2 MUST categorize, then count the frames into one of two groups: Port 2 MUST categorize, then count the frames into one of two groups:
1.) Received Frames: received frames MUST have the correct 1.) Received Frames: received frames MUST have the correct
destination MAC address and SHOULD match a signature field. destination MAC address and SHOULD match a signature field.
2.) Flood count: defined in RFC 2285 3.8.3. 2.) Flood count [2].
Any frame received which does not have the correct destination
address MUST not be counted as a received frame and SHOULD be counted
as part of a flood count.
Any frame originating from the DUT/SUT MUST not be counted as a Any frame originating from the DUT/SUT MUST not be counted as a
received frame. Frames originating from the DUT/SUT MAY be counted received frame. Frames originating from the DUT/SUT MAY be counted
as flooded frames or not counted at all. as flooded frames or not counted at all.
5.8.5 Reporting format 5.6.5 Reporting format
Maximum forwarding rate (MFR) MUST be reported as the highest MFR MUST be reported as the highest forwarding rate of a DUT/SUT
forwarding rate of a DUT/SUT taken from an iterative set of taken from an iterative set of forwarding rate measurements. The
forwarding rate measurements. The load applied to the device MUST Iload applied to the device MUST also be cited.
also be cited.
Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
of frames per second that the device is observed to successfully of frames per second that the device is observed to successfully
transmit to the correct destination interface in response to a transmit to the correct destination interface in response to a
specified offered load. The offered load MUST also be cited. specified Oload. The Iload MUST be cited and the Oload MAY be
recorded.
5.9 Address Caching Capacity If the FR exceeds the MOL during the Minimum Interframe gap test,
this MUST be highlighted with the expression "Forward Pressure
detected".
5.9.1 Objective 5.7 Address Caching Capacity
5.7.1 Objective
To determine the address caching capacity of a LAN switching device To determine the address caching capacity of a LAN switching device
as defined in RFC 2285, section 3.8.1. as defined in RFC 2285, section 3.8.1 [2].
5.9.2 Setup Parameters 5.7.2 Setup Parameters
The following parameters MUST be defined. Each variable is The following parameters MUST be defined. Each variable is
configured with the following considerations. configured with the following considerations.
Age Time - The maximum time that a DUT/SUT will keep a learned Age Time - The maximum time that a DUT/SUT will keep a learned
address in its forwarding table. address in its forwarding table.
Addresses Learning Rate - The rate at which new addresses are Addresses Learning Rate - The rate at which new addresses are
offered to the DUT/SUT to be learned. The rate at which address offered to the DUT/SUT to be learned. The rate at which address
learning frames are offered may have to be adjusted to be as low as learning frames are offered may have to be adjusted to be as low as
50 frames per second or even less, to guarantee successful 50 frames per second or even less, to guarantee successful
learning. learning.
Initial Addresses - The initial number of addresses to start the Initial Addresses - The initial number of addresses to start the
test with. The number MUST be between 1 and the maximum number test with. The number MUST be between 1 and the maximum number
supported by the implementation. supported by the implementation.
5.9.3 Procedure 5.7.3 Procedure
The aging time of the DUT/SUT MUST be known. The aging time MUST be The aging time of the DUT/SUT MUST be known. The aging time MUST be
longer than the time necessary to produce frames at the specified longer than the time necessary to produce frames at the specified
rate. If a low frame rate is used for the test, then it may be rate. If a low frame rate is used for the test, then it may be
possible that sending a large amount of frames may actually take possible that sending a large amount of frames may actually take
longer than the aging time. longer than the aging time.
This test SHOULD at a minimum be performed in a three-port This test MUST at a minimum be performed in a three-port
configuration as described below. configuration described below. The test MAY be expanded to fully
utilized the DUT/SUT in increments of two or three ports. An
This test MUST consist of a multiple of three ports. Three ports increment of two would include an additional Learning port and Test
are REQUIRED and MAY be expanded to fully utilized the DUT/SUT in port. An increment of three would include an additional Learning
increments of three. Each group of three will contain a test port, Test port, and Monitoring port.
block as follows:
The first port (port 1) send frames with varying source addresses and The Learning port (Lport) transmits learning frames to the DUT/SUT
a fixed destination address corresponding to the MAC address of the with varying source addresses and a fixed destination address
receiving port (port 2) of the DUT/SUT. By receiving frames with corresponding to the address of the device connected to the Test port
varying source addresses, the DUT/SUT will learn these new addresses (Tport) of the DUT/SUT. By receiving frames with varying
from the sending port of the test device. The source addresses MAY source addresses, the DUT/SUT should learn these new addresses. The
be in sequential order. source addresses MAY be in sequential order.
A second port (port 2) acts as the receiving port for the address The Test port (Tport) of the DUT/SUT acts as the receiving port for
learning frames. This port also sends test frames back to the the learning frames. Test frames will be transmitted back to the
addresses learned on the first port. The algorithm for this is addresses learned on the Learning port. The algorithm for this is
explained below. explained below.
A third port (port 3) on the DUT/SUT act as a monitoring port to The Monitoring port (Mport) on the DUT/SUT acts as a monitoring port
listen for flooded frames. to listen for flooded or mis-forwarded frames. If the test spans
multiple broadcast domains (VLANs), each broadcast domain REQUIRES a
Monitoring port.
It is highly recommended that SNMP, Spanning Tree, and any other It is highly recommended that SNMP, Spanning Tree, and any other
frames originating from the DUT/SUT be disabled when running this frames originating from the DUT/SUT be disabled when running this
test. If such protocols cannot be turned off, the flood count MUST test. If such protocols cannot be turned off, the flood count MUST
be modified only to count frame originating from port 1 and MUST be modified only to count test frame originating from Lport and MUST
NOT count frames originating from the DUT/SUT. NOT count frames originating from the DUT/SUT.
The algorithm for the test is as follows: The algorithm for the test is as follows:
CONSTANT CONSTANT
AGE = ...; {value greater that DUT aging time} AGE = ...; {value greater that DUT aging time}
MAX = ...; {maximum address support by implementation} MAX = ...; {maximum address support by implementation}
VARIABLE VARIABLE
LOW := 0; {Highest passed valve} LOW := 0; {Highest passed valve}
HIGH := MAX; {Lowest failed value} HIGH := MAX; {Lowest failed value}
N := ...; {user specified initial starting point} N := ...; {user specified initial starting point}
BEGIN BEGIN
skipping to change at page 25, line 23 skipping to change at page 23, line 18
AGE = ...; {value greater that DUT aging time} AGE = ...; {value greater that DUT aging time}
MAX = ...; {maximum address support by implementation} MAX = ...; {maximum address support by implementation}
VARIABLE VARIABLE
LOW := 0; {Highest passed valve} LOW := 0; {Highest passed valve}
HIGH := MAX; {Lowest failed value} HIGH := MAX; {Lowest failed value}
N := ...; {user specified initial starting point} N := ...; {user specified initial starting point}
BEGIN BEGIN
DO DO
BEGIN BEGIN
PAUSE(AGE); {Age out any learned addresses} PAUSE(AGE); {Age out any learned addresses}
AddressLearning(Port 2); {broadcast a frame with its source AddressLearning(TPort); {broadcast a frame with its source
Address and broadcast destination} Address and broadcast destination}
AddressLearning(Port 1); {N frames with varying source AddressLearning(LPort); {N frames with varying source
addresses addresses
to Port 2} to Test Port}
Transmit(Port 2); {N frames with varying destination addresses Transmit(TPort); {N frames with varying destination addresses
corresponding to Port 1} corresponding to Learning Port}
IF (Port 3 receive frame != 0) OR IF (MPort receive frame != 0) OR
(Port 1 receive frames < Port 2 transmit) THEN (LPort receive frames < TPort transmit) THEN
BEGIN {Address Table of DUT/SUT was full} BEGIN {Address Table of DUT/SUT was full}
HIGH := N; HIGH := N;
END END
ELSE ELSE
BEGIN {Address Table of DUT/SUT was NOT full} BEGIN {Address Table of DUT/SUT was NOT full}
LOW := N; LOW := N;
END END
N := LOW + (HIGH - LOW)/2; N := LOW + (HIGH - LOW)/2;
END WHILE (HIGH - LOW < 2); END WHILE (HIGH - LOW < 2);
END {Value of N equals number of addresses supported by DUT/SUT} END {Value of N equals number of addresses supported by DUT/SUT}
Using a binary search approach, the test targets the exact number of Using a binary search approach, the test targets the exact number of
addresses supported per port with consistent test iterations. Due addresses supported per port with consistent test iterations. Due
to the aging time of DUT/SUT address tables, each iteration may take to the aging time of DUT/SUT address tables, each iteration may take
some time during the waiting period for the addresses to clear. If some time during the waiting period for the addresses to clear. If
possible, configure the DUT/SUT for a low value for the aging time. possible, configure the DUT/SUT for a low value for the aging time.
Once the high and low values of N meet, then the threshold of address Once the high and low values of N meet, then the threshold of address
handling has been found. handling has been found.
5.9.4 Measurements 5.7.4 Measurements
Whether the offered addresses per port was successful forwarded Whether the offered addresses per port was successful forwarded
without flooding. without flooding.
5.9.5 Reporting format 5.7.5 Reporting format
After the test is run, results for each iteration SHOULD be displayed After the test is run, results for each iteration SHOULD be displayed
in a table to include: in a table to include:
The number of addresses used for each test iteration (varied). The number of addresses used for each test iteration (varied).
The intended load used for each test iteration (fixed). The intended load used for each test iteration (fixed).
Number of test frames that were transmitted by test port number 2. Number of test frames that were offered to Tport of the DUT/SUT.
This SHOULD match the number of addresses used for the test This SHOULD match the number of addresses used for the test
iteration. Test frames are the frames sent with varying iteration. Test frames are the frames sent with varying
destination addresses to confirm that the DUT/SUT has learned destination addresses to confirm that the DUT/SUT has learned
all of the addresses for each test iteration. all of the addresses for each test iteration.
The flood count on port 2 during the test portion of each test. The flood count on Tport during the test portion of each test.
If the number is non-zero, this is an indication of the DUT/SUT If the number is non-zero, this is an indication of the DUT/SUT
flooding a frame in which the destination address is not in the flooding a frame in which the destination address is not in the
address table. address table.
The number of frames correctly forwarded to test port 1 during The number of frames correctly forwarded to test Lport during
the test portion of the test. Received frames MUST have the the test portion of the test. Received frames MUST have the
correct destination MAC address and SHOULD match a signature correct destination MAC address and SHOULD match a signature
field. For a passing test iteration, this number should be equal field. For a passing test iteration, this number should be equal
to the number of frames transmitted by port 2. to the number of frames transmitted by Tport.
The flood count on port 1 during the test portion of each test. The flood count on Lport during the test portion of each test.
If the number is non-zero, this is an indication of the DUT/SUT If the number is non-zero, this is an indication of the DUT/SUT
flooding a frame in which the destination address is not in the flooding a frame in which the destination address is not in the
address table. address table.
The flood count on port 3. If the value is not zero, then this The flood count on Mport. If the value is not zero, then this
indicates that for that test iteration, the DUT/SUT could not indicates that for that test iteration, the DUT/SUT could not
determine the proper destination port for that many frames. In determine the proper destination port for that many frames. In
other words, the DUT/SUT flooded the frame to all ports since its other words, the DUT/SUT flooded the frame to all ports since its
address table was full. address table was full.
5.10 Address Learning Rate 5.8 Address Learning Rate
5.10.1 Objective 5.8.1 Objective
To determine the rate of address learning of a LAN switching device To determine the rate of address learning of a LAN switching device.
as defined in RFC 2285, section 3.8.2.
5.10.2 Setup Parameters 5.8.2 Setup Parameters
The following parameters MUST be defined. Each variable is The following parameters MUST be defined. Each variable is
configured with the following considerations. configured with the following considerations.
Age Time - The maximum time that a DUT/SUT will keep a learned Age Time - The maximum time that a DUT/SUT will keep a learned
address in its forwarding table. address in its forwarding table.
Initial Addresses Learning Rate - The starting rate at which new Initial Addresses Learning Rate - The starting rate at which new
addresses are offered to the DUT/SUT to be learned. addresses are offered to the DUT/SUT to be learned.
Number of Addresses - The number of addresses that the DUT/SUT must Number of Addresses - The number of addresses that the DUT/SUT must
learn. The number MUST be between 1 and the maximum number learn. The number MUST be between 1 and the maximum number
supported by the implementation. It is recommended no to exceed supported by the implementation. It is recommended no to exceed
the address caching capacity found in section 5.9 the address caching capacity found in section 5.9
5.10.3 Procedure 5.8.3 Procedure
The aging time of the DUT/SUT MUST be known. The aging time MUST be The aging time of the DUT/SUT MUST be known. The aging time MUST be
longer than the time necessary to produce frames at the specified longer than the time necessary to produce frames at the specified
rate. If a low frame rate is used for the test, then it may be rate. If a low frame rate is used for the test, then it may be
possible that sending a large amount of frames may actually take possible that sending a large amount of frames may actually take
longer than the aging time. longer than the aging time.
This test SHOULD at a minimum be performed in a three-port This test MUST at a minimum be performed in a three-port
configuration as described below. configuration in section 5.9.3. The test MAY be expanded to fully
utilized the DUT/SUT in increments of two or three ports. An
This test MUST consist of a multiple of three ports. Three ports increment of two would include an additional Learning port and Test
are REQUIRED and MAY be expanded to fully utilized the DUT/SUT in port. An increment of three would include an additional Learning
increments of three. Each group of three will contain a test port, Test port, and Monitoring port.
block as described in section 5.9.
An algorithm similar to the one used to determine address caching An algorithm similar to the one used to determine address caching
capacity can be used to determine the address learning rate. This capacity can be used to determine the address learning rate. This
test iterates the rate at which address learning frames are offered test iterates the rate at which address learning frames are offered
by the test device connected to the DUT/SUT. It is recommended to by the test device connected to the DUT/SUT. It is recommended to
set the number of addresses offered to the DUT/SUT in this test to set the number of addresses offered to the DUT/SUT in this test to
the maximum caching capacity. the maximum caching capacity.
The address learning rate might be determined for different numbers The address learning rate might be determined for different numbers
of addresses but in each test run, the number MUST remain constant of addresses but in each test run, the number MUST remain constant
and SHOULD be equal to or less than the maximum address caching and SHOULD be equal to or less than the maximum address caching
capacity. capacity.
5.10.4 Measurements 5.8.4 Measurements
Whether the offered addresses per port was successful forwarded Whether the offered addresses per port were successful forwarded
without flooding at the offered learning rate. without flooding at the offered learning rate.
5.10.5 Reporting format 5.8.5 Reporting format
After the test is run, results for each iteration SHOULD be displayed After the test is run, results for each iteration SHOULD be displayed
in a table: in a table:
The number of addresses used for each test iteration (fixed). The number of addresses used for each test iteration (fixed).
The intended load used for each test iteration (varied). The intended load used for each test iteration (varied).
Number of test frames that were transmitted by test port number 2. Number of test frames that were transmitted by Tport. This SHOULD
This SHOULD match the number of addresses used for the test match the number of addresses used for the test iteration. Test
iteration. Test frames are the frames sent with varying frames are the frames sent with varying destination addresses to
destination addresses to confirm that the DUT/SUT has learned confirm that the DUT/SUT has learned all of the addresses for each
all of the addresses for each test iteration. test iteration.
The flood count on port 2 during the test portion of each test. The flood count on Tport during the test portion of each test.
If the number is non-zero, this is an indication of the DUT/SUT If the number is non-zero, this is an indication of the DUT/SUT
flooding a frame in which the destination address is not in the flooding a frame in which the destination address is not in the
address table. address table.
The number of frames correctly forwarded to test port 1 during The number of frames correctly forwarded to test Lport during
the test portion of the test. Received frames MUST have the the test portion of the test. Received frames MUST have the
correct destination MAC address and SHOULD match a signature correct destination MAC address and SHOULD match a signature
field. For a passing test iteration, this number should be equal field. For a passing test iteration, this number should be equal
to the number of frames transmitted by port 2. to the number of frames transmitted by Tport.
The flood count on port 1 during the test portion of each test. The flood count on Lport during the test portion of each test.
If the number is non-zero, this is an indication of the DUT/SUT If the number is non-zero, this is an indication of the DUT/SUT
flooding a frame in which the destination address is not in the flooding a frame in which the destination address is not in the
address table. address table.
The flood count on port 3. If the value is not zero, then this The flood count on Mport. If the value is not zero, then this
indicates that for that test iteration, the DUT/SUT could not indicates that for that test iteration, the DUT/SUT could not
determine the proper destination port for that many frames. In determine the proper destination port for that many frames. In
other words, the DUT/SUT flooded the frame to all ports since its other words, the DUT/SUT flooded the frame to all ports since its
address table was full. address table was full.
5.9 Errored frames filtering
5.9.1 Objective
The objective of the Errored frames filtering test is to determine
the behavior of the DUT under error or abnormal frame conditions.
The results of the test indicate if the DUT/SUT filters the errors,
or simply propagates the errored frames along to the destination.
5.9.2 Setup Parameters
The following parameters MUST be defined. Each variable is
configured with the following considerations.
ILoad - Intended Load per port is expressed in a percentage of the
medium's maximum theorical load possible. The actual transmitted
frame per second is dependent upon half duplex or full duplex
operation. The test SHOULD be run multiple times with a different
load per port in each case.
Trial Duration - The recommended Trial Duration is 30 seconds.
Trial duration SHOULD be adjustable between 1 and 300 seconds.
5.9.3 Procedure
Each of the illegal frames for Ethernet MUST be checked:
Oversize - The DUT/SUT MAY filter frames larger than 1518 bytes
from being propagated through the DUT/SUT section 4.2.4.2.1 [4].
Oversized frames transmitted to the DUT/SUT should not be forwarded.
DUT/SUT supporting tagged Frames MAY forward frames up to and
including 1522 bytes long (section 4.2.4.2.1 [5]).
Undersize - The DUT/SUT MUST filter frames less than 64 bytes from
being propagated through the DUT/SUT (section 4.2.4.2.2 [4]).
Undersized frames (or collision fragments) received by the DUT/SUT
must not be forwarded.
CRC Errors - The DUT/SUT MUST filter frames that fail the Frame Check
Sequence Validation (section 4.2.4.1.2 [4]) from being propagated
through the DUT/SUT. Frames with an invalid CRC transmitted to the
DUT/SUT should not be forwarded.
Dribble Bit Errors - The DUT/SUT MUST correct and forward frames
containing dribbling bits. Frames transmitted to the DUT/SUT that do
not end in an octet boundary but contain a valid frame check sequence
MUST be accepted by the DUT/SUT (section 4.2.4.2.1 [4]) and forwarded
to the correct receive port with the frame ending in an octet
boundary (section 3.4 [4]).
Alignment Errors - The DUT/SUT MUST filter frames that fail the Frame
Check Sequence Validation AND do not end in an octet boundary. This
is a combination of a CRC error and a Dribble Bit error. When both
errors are occurring in the same frame, the DUT/SUT MUST determine
the CRC error takes precedence and filters the frame (section
4.2.4.1.2 [4]) from being propagated.
5.9.5 Reporting format
For each of the error conditions in section 5.6.3, a "pass" or "fail"
MUST be reported. Actual frame counts MAY be reported for diagnostic
purposes.
5.10 Broadcast frame Forwarding and Latency
5.10.1 Objective
The objective of the Broadcast Frame Forwarding and Latency Test is
to determine the throughput and latency of the DUT when forwarding
broadcast traffic. The ability to forward broadcast frames will
depend upon a specific function built into the device for that
purpose. It is therefore necessary to determine the ability of
DUT/SUT to handle broadcast frames, since there may be many different
ways of implementing such a function.
5.10.2 Setup Parameters
The following parameters MUST be defined. Each variable is
configured with the following considerations.
Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
1280 and 1518 bytes, per RFC 2544 section 9 [3]. The four CRC
bytes are included in the frame size specified.
Duplex mode - Half duplex or full duplex.
ILoad - Intended Load per port is expressed in a percentage of the
medium's maximum theoretical load, regardless of traffic
orientation or duplex mode. Certain test configurations will
theoretically over-subscribe the DUT/SUT.
ILoad will not over-subscribe the DUT/SUT in this test.
Trial Duration - The recommended Trial Duration is 30 seconds.
Trial duration SHOULD be adjustable between 1 and 300 seconds.
5.10.3 Procedure
For this test, there are two parts to be run.
Broadcast Frame Throughput - This portion of the test uses a single
source test port to transmit test frames with a broadcast address
using the frame specified in RFC 2544 [3]. Selected receive ports
then measure the forwarding rate and Frame loss rate.
Broadcast Frame Latency - This test uses the same setup as the
Broadcast Frame throughput, but instead of a large stream of test
frames being sent, only one test frame is sent and the latency to
each of the receive ports are measured in seconds.
5.10.4 Measurements
Frame loss rate of the DUT/SUT SHOULD be reported as defined in
section 26.3 [3] with the following notes: Frame loss rate SHOULD be
measured at the end of the trial duration. The term "rate", for this
measurement only, does not imply the units in the fashion of "per
second."
Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
of test frames per second that the device is observed to successfully
forward to the correct destination interface in response to a
specified Oload. The Oload MUST also be cited.
5.10.5 Reporting format
The results for these tests SHOULD be reported in the form of a
graph. The x coordinate SHOULD be the frame size, the y coordinate
SHOULD be the test results. There SHOULD be at least two lines on
the graph, one plotting the theoretical and one plotting the test
results.
To measure the DUT/SUT's ability to switch traffic while performing
many different address lookups, the number of addresses per port
MAY be increased in a series of tests.
6. Security Considerations 6. Security Considerations
This document does not yet address Security Considerations. This document does not yet address Security Considerations.
7. Authors' Address 7. References
[1] Bradner, S., Editor, "Benchmarking Terminology for Network
Interconnection Devices", RFC 1242, July 1991.
[2] Mandeville, R., Editor, "Benchmarking Terminology for LAN
Switching Devices", RFC 2285, February 1998.
[3] Bradner, S., Editor, "Benchmarking Methodology for Network
Interconnect Devices", RFC 2544, March 1999.
[4] ANSI/IEEE, "CSMA/CD Access Method and Physical Layer
Specifications," ISO/IEC 8802-3, ISBN 0-7381-0330-6, 1998.
[5] IEEE Draft, "Frame Extensions for Virtual Bridged Local Area
Networks (VLAN) Tagging on 802.3 Networks", 802.3ac/D3.1,
July 1998.
8. Authors' Address
Robert Mandeville Robert Mandeville
European Network Laboratories (ENL) European Network Laboratories (ENL)
2, rue Helene Boucher 2, rue Helene Boucher
87286 Guyancourt Cedex 87286 Guyancourt Cedex
France France
Phone: + 33 1 39 44 12 05 Phone: + 33 1 39 44 12 05
EMail: bob@enl.net EMail: bob@enl.net
skipping to change at page 29, line 9 skipping to change at page 31, line 9
Chatsworth, CA 91311 Chatsworth, CA 91311
USA USA
Phone: + 1 818 700 5100 Phone: + 1 818 700 5100
Email: jerry_perser@netcomsystems.com Email: jerry_perser@netcomsystems.com
Appendix A: Formulas Appendix A: Formulas
A.1 Calculating the InterBurst Gap A.1 Calculating the InterBurst Gap
IBG is defined in RFC 2285 as the interval between two bursts. To IBG is defined in RFC 2285 [2] as the interval between two bursts.
achieve a desired load, the follow Input Parameter need to be To achieve a desired load, the follow Input Parameter need to be
defined: defined:
LENGTH - Frame size in bytes including the CRC. LENGTH - Frame size in bytes including the CRC.
LOAD - The intended load in percent. Range is 0 to 100. LOAD - The intended load in percent. Range is 0 to 100.
BURST - The number of frames in the burst (integer value). BURST - The number of frames in the burst (integer value).
SPEED - media's speed in bits/sec SPEED - media's speed in bits/sec
Ethernet is 10,000,000 bits/sec Ethernet is 10,000,000 bits/sec
Fast Ethernet is 100,000,000 bits/sec Fast Ethernet is 100,000,000 bits/sec
Gigabit Ethernet is 1,000,000,000 bits/sec Gigabit Ethernet is 1,000,000,000 bits/sec
DUPLEX - A constant to adjust the transmit rate for full or half
duplex mode. In full duplex the value is 100, in half
duplex the value is 200.
IFG - A constant 96 bits for the minimum interframe gap. IFG - A constant 96 bits for the minimum interframe gap.
The IBG (in seconds) can be calculated: The IBG (in seconds) can be calculated:
(DUPLEX/LOAD - 1) * BURST * (IFG + 64 + 8*LENGTH)] + IFG [(100/LOAD - 1) * BURST * (IFG + 64 + 8*LENGTH)] + IFG
IBG = ---------------------------------------------------------- IBG = -----------------------------------------------------------
SPEED SPEED
A.2 Calculating the Number of Bursts for the Test Duration A.2 Calculating the Number of Bursts for the Trial Duration
The number of burst for the test duration is rounded up to the The number of burst for the trial duration is rounded up to the
nearest nearest integer number. The follow Input Parameter need to be
integer number. The follow Input Parameter need to be defined: defined:
LENGTH - Frame size in bytes including the CRC. LENGTH - Frame size in bytes including the CRC.
BURST - The number of frames in the burst (integer value). BURST - The number of frames in the burst (integer value).
SPEED - media's speed in bits/sec SPEED - media's speed in bits/sec
Ethernet is 10,000,000 bits/sec Ethernet is 10,000,000 bits/sec
Fast Ethernet is 100,000,000 bits/sec Fast Ethernet is 100,000,000 bits/sec
Gigabit Ethernet is 1,000,000,000 bits/sec Gigabit Ethernet is 1,000,000,000 bits/sec
IFG - A constant 96 bits for the minimum interframe gap. IFG - A constant 96 bits for the minimum interframe gap.
IBG - Found in the above formula IBG - Found in the above formula
DURATION - Test duration in seconds.
DURATION - Trial duration in seconds.
An intermediate number of the Burst duration needs to be calculated An intermediate number of the Burst duration needs to be calculated
first: first:
IFG*(BURST-1) + BURST*(64 + 8*LENGTH) IFG*(BURST-1) + BURST*(64 + 8*LENGTH)
TXTIME = ----------------------------------------- TXTIME = -----------------------------------------
SPEED SPEED
Number of Burst for the Test Duration (rounded up): Number of Burst for the Trial Duration (rounded up):
DURATION DURATION
#OFBURSTS = -------------- #OFBURSTS = --------------
(TXTIME + IBG) (TXTIME + IBG)
Example: Example:
LENGTH = 64 bytes per frame LENGTH = 64 bytes per frame
LOAD = 100 % offered load LOAD = 100 % offered load
BURST = 24 frames per burst BURST = 24 frames per burst
SPEED = 10 Mbits/sec (Ethernet) SPEED = 10 Mbits/sec (Ethernet)
DUPLEX = 200 (half duplex)
DURATION = 10 seconds test DURATION = 10 seconds test
IBG = 1612.8 uS IBG = 1612.8 uS
TXTIME = 1603.2 uS TXTIME = 1603.2 uS
#OFBURSTS = 3110 #OFBURSTS = 3110
Appendix B: Generating Offered Load
In testing, the tester is configured with the Iload (Intended Load)
and measures the Oload (Offered Load). If the DUT/SUT applies
backpressure, then the Iload and the Oload are not the same value.
The question arises, how to generate the Oload? This appendix will
describe two different methods.
Oload is in the units of bits per second. The two methods described
here will hold one unit constant and let the DUT/SUT vary the other
unit. The tester SHOULD specify which method it uses.
B.1 Frame Based Load
Frame based load holds the number of bits constant. The Trial
Duration will vary based upon back pressure. Advantage is
implementation is a simple state machine. Disadvantage is that Oload
needs to be measured independently.
All ports on the tester MUST transmit the exact number of test
frames. The exact number is found by multiplying the Iload by the
Trial Duration. All ports MAY NOT transmit the same number of frames
if their Iload is not the same. An example would be the Partially
meshed overloading test.
All ports SHOULD start transmitting their frames within 1% of the
trial duration. For a trial duration of 30 seconds, all ports SHOULD
have started transmitting frames within 300 milliseconds of each
other.
Oload MUST be measured independent of Iload. The reported Oload
SHOULD be the average during the Trial Duration. If the tester
continues to transmit after the Trial Duration due to back pressure,
Oload MAY be averaged over the entire transmit time. Oload for the
DUT/SUT MUST be the aggregate of all the Oloads per port. Oload per
port MAY be reported for diagnostic purposes.
B.2 Time Based Load
Time based load holds the Trial Duration constant, while allowing the
number of octets transmitted to vary. Advantages are an accurate
Trial Duration and integrated Oload measurement. Disadvantage is
that the starting and stopping of the transmitters MUST be more
accurate.
All ports on the tester are configured to transmit the Iload for an
indefinite amount of time. Each port MUST count the number of
octets successfully transmitted.
All ports MUST start transmitting their frames within 1% of the trial
duration. For a trial duration of 30 seconds, all ports SHOULD have
started transmitting frames within 300 milliseconds of each other.
All ports SHOULD stop transmitting frames after the specified trial
duration, within 100 PPM. The first test frame transmit time minus
the last test frame transmit time SHOULD be within 100 PPM of the
trial duration. Each port's stop time MUST be in reference to its
start time. This trial duration error controls the accuracy of the
Oload measurement and SHOULD be reported with the Oload measurement
in the units of PPM.
Each port is allowed an offset error of 1000 PPM and a trial duration
error of 100 PPM. At what layer the start and stop is initiated is
not defined yet. The layer MUST complete its transmit process when
the stop time is reached (i.e. no fragments, finish the frame).
Oload is found by taking the number of octets successfully
transmitted and dividing by the trial duration. Oload for the
DUT/SUT MUST be the aggregate of all the Oloads per port. Oload per
port MAY be reported for diagnostic purposes.
 End of changes. 

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