draft-ietf-bmwg-igp-dataplane-conv-term-00.txt   draft-ietf-bmwg-igp-dataplane-conv-term-01.txt 
Network Working Group Network Working Group
INTERNET-DRAFT INTERNET-DRAFT
Expires in: December 2003 Expires in: April 2004
Scott Poretsky Scott Poretsky
Avici Systems Quarry Technologies
June 2003 Brent Imhoff
Wiltel Communications
October 2003
Terminology for Benchmarking Terminology for Benchmarking
IGP Data Plane Route Convergence IGP Data Plane Route Convergence
<draft-ietf-bmwg-igp-dataplane-conv-term-00.txt> <draft-ietf-bmwg-igp-dataplane-conv-term-01.txt>
Status of this Memo Status of this Memo
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all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
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Table of Contents Table of Contents
1. Introduction ...............................................2 1. Introduction ...............................................2
2. Existing definitions .......................................2 2. Existing definitions .......................................2
3. Term definitions............................................2 3. Term definitions............................................3
3.1 Network Convergence.....................................2 3.1 Network Convergence.......................................3
3.2 Protocol Convergence....................................3 3.2 Protocol Convergence......................................3
3.3 Route Convergence.......................................3 3.3 Route Convergence.........................................4
3.4 Full Route Convergence Time.............................4 3.4 Convergence Event.........................................4
3.5 Route Convergence Packet Loss...........................5 3.5 Full Convergence..........................................4
3.6 Average Route Convergence Time..........................5 3.6 Convergence Packet Loss...................................5
3.7 Route Convergence Event Slope...........................6 3.7 Convergence Event Instant.................................5
3.8 Route Convergence Recovery Slope........................6 3.8 Convergence Recovery Transition...........................6
3.9 Reroute Convergence Time...............................7 3.9 Rate-Derived Convergence Time.............................6
3.10 Local Interface........................................7 3.10 Convergence Recovery Instant.............................7
3.11 Neighbor Interface.....................................8 3.11 Convergence Event Transition.............................7
3.12 Remote Interface.......................................8 3.12 Loss-Derived Convergence Time............................8
4. Security Considerations.....................................8 IGP Data Plane Route Convergence
5. References..................................................9
IGP Route Convergence
7. Author's Address............................................9 3.13 Route Convergence Time...................................9
8. Full Copyright Statement....................................9 3.14 Restoration Convergence Time.............................9
3.15 Packet Sampling Interval.................................10
3.16 Local Interface..........................................10
3.17 Neighbor Interface.......................................10
3.18 Remote Interface.........................................11
3.19 Preferred Egress Interface...............................11
3.20 Next-Best Egress Interface...............................12
4. Security Considerations.....................................12
5. References..................................................12
6. Author's Address............................................12
7. Full Copyright Statement....................................13
1. Introduction 1. Introduction
This draft describes the terminology for benchmarking IGP Route This draft describes the terminology for benchmarking IGP Route
Convergence. The motivation and applicability for this Convergence. The motivation and applicability for this
benchmarking is provided in [1]. The methodology to be used for benchmarking is provided in [1]. The methodology to be used for
this benchmarking is described in [2]. The methodology and this benchmarking is described in [2]. The methodology and
terminology to be used for benchmarking route convergence can be terminology to be used for benchmarking route convergence can be
applied to any link-state IGP such as ISIS [3] and OSPF [4]. The applied to any link-state IGP such as ISIS [3] and OSPF [4]. The
data plane is measured to obtain the convergence benchmarking metrics. data plane is measured to obtain black-box (externally observable)
The purpose of this document is to introduce new terms required to convergence benchmarking metrics. The purpose of this document is
complete execution of the IGP Route Convergence Methodology [2]. to introduce new terms required to complete execution of the IGP
Route Convergence Methodology [2].
2. Existing definitions An example of Route Convergence as observed and measured from the
data plane is shown in Figure 1. The graph in Figure 1 shows
Forwarding Rate versus Time. Time 0 on the X-axis is on the far
right of the graph. The components of the graph and metrics are
defined in the Term Definitions section of this document.
Recovery Convergence Event Time = 0sec
Maximum ^ ^ ^
Forwarding Rate--> ----\ Packet /---------------
\ Loss /<----Convergence
Convergence------->\ / Event Transition
Recovery Transition \ /
\_____/<------100% Packet Loss
X-axis = Time
Y-axis = Forwarding Rate
Figure 1. Convergence Graph
2. Existing definitions
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 definitions set out in Section 2 of RFC 1242. Definitions are for definitions set out in Section 2 of RFC 1242. Definitions are
indexed and grouped together in sections for ease of reference. indexed and grouped together in sections for ease of reference.
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. Term definitions IGP Data Plane Route Convergence
3. Term Definitions
3.1 Network Convergence 3.1 Network Convergence
Definition: Definition:
The completion of updating of all routing tables, including the The completion of updating of all routing tables, including the
FIB, in all routers throughout the network. FIB, in all routers throughout the network.
Discussion: Discussion:
Network Convergence can be approximated to the sum of Route Network Convergence can be approximated to the sum of Route
Convergence for all routers in the network. Network Convergence Convergence for all routers in the network. Network Convergence
can only be determined by the occurrence of packet loss or stale can only be determined by the occurrence of packet loss or stale
forwarding due to an out-of-date FIB. forwarding due to an out-of-date FIB.
Measurement Units: Measurement Units:
Converged or Not Converged N/A
Issues: Issues:
None None
See Also: See Also:
Protocol Convergence Protocol Convergence
Route Convergence Route Convergence
IGP Data Plane Route Convergence
3.2 Protocol Convergence 3.2 Protocol Convergence
Definition: Definition:
The completion of updating a router's RIB and the forwarding of The completion of updating a router's RIB and the forwarding of
an route update message (LSA for OSPF/LSP for ISIS) to a an route update message (LSA for OSPF/LSP for ISIS) to a
neighboring peer. neighboring peer.
Discussion: Discussion:
Protocol Convergence considers only the Control Plane. IGP Protocol Convergence considers only the Control Plane. IGP
messaging is used to verify and measure convergence. Updating messaging is used to verify and measure convergence. Updating
of the FIB, hardware updating, rerouting of traffic, and packet of the FIB, hardware updating, rerouting of traffic, and packet
loss are not considered. loss are not considered.
Measurement Units: Measurement Units:
LSA/LSP Transmitted or LSA/LSP Not Transmitted. N/A
Issues: Issues:
Protocol Convergence does not consider updating of the FIB, Protocol Convergence does not consider updating of the FIB,
hardware updating, rerouting of traffic, and resultant packet hardware updating, rerouting of traffic, and resulting packet
loss. Protocol Convergence is only a partial measurement of loss. Protocol Convergence is only a partial measurement of
Route Convergence. Route Convergence.
See Also: See Also:
Network Convergence Network Convergence
Route Convergence Route Convergence
IGP Data Plane Route Convergence
3.3 Route Convergence 3.3 Route Convergence
Definition: Definition:
The completion of the router's FIB becoming fully converged. The completion of the router's FIB becoming fully converged.
Discussion: Discussion:
All components of the router have been updated with the most Route Convergence is the action of all components of the router
recent route change(s) including the RIB and FIB, along with being updated with the most recent route change(s) including the
software and hardware tables. Route Convergence can be observed RIB and FIB, along with software and hardware tables. Route
externally by the rerouting of data traffic. Convergence can be observed externally by the rerouting of data
Traffic to a new egress interface.
Measurement Units: Measurement Units:
Converged or Not Converged N/A
Issues: Issues:
None None
See Also: See Also:
Route Convergence Time
Network Convergence Network Convergence
Protocol Convergence Protocol Convergence
IGP Data Plane Route Convergence Full Convergence
Convergence Event
3.4 Full Route Convergence Time 3.4 Convergence Event
Definition: Definition:
The amount of time it takes for Route Convergence to The occurrence of a planned or unplanned action in the network
complete as measured by the time to drop from maximum that results in a change to an entry in the route table.
forwarding rate and return to maximum forwarding rate
after occurrence of a network event.
Discussion: Discussion:
Full Route Convergence Time is a metric applied Convergence Events include link loss, routing protocol session
to a single router. Convergence Time could be calculated loss, router failure, and better next-hop.
from packet loss. However, this will give a better than
actual result when converging many routes simultaneously.
The preferred method to obtain Route Convergence Time is
to measure the time to drop from maximum forwarding rate
and return to maximum forwarding rate.
Figure 1 shows a graph model of Convergence Time as measured Measurement Units:
from the data plane. IGP Route Convergence Time is the N/A
amount of time for the Forwarding Rate to begin its downward
slope upon occurrence of a network event and then fully recover
to the Maximum Forwarding Rate. This is calculated as
(eq 1) Time(Convergence) = Time(Recovery) - Time(Network Event). Issues:
None
Forwarding Rate versus Time See Also:
Convergence Packet Loss
Convergence Event Instant
Time=Recovery Time=Network Event Time = 0sec 3.5 Full Convergence
Maximum ^ ^ ^
Forwarding Rate--> ----\ /-----------
\ /<----Route Convergence
Route Convergence------->\ / Event Slope
Recovery Slope \_______/<------100% Packet Loss
X-axis = Time Definition:
Y-axis = Forwarding Rate Route Convergence for an entire route table.
Figure 1. Convergence Graph Discussion:
When benchmarking convergence it is useful to measure
The time to convergence an entire route table. For example,
IGP Data Plane Route Convergence
A Convergence Event can produced for an OSPF table of 5000
routes so that the time to converge routes 1 through 5000
is measured.
Measurement Units: Measurement Units:
seconds/milliseconds N/A
Issues: Issues:
None None
See Also: See Also:
Network Convergence
Protocol Convergence
Route Convergence Route Convergence
Route Convergence Packet Loss Convergence Event
Average Route Convergence Time
IGP Data Plane Route Convergence
3.5 Route Convergence Packet Loss 3.6 Convergence Packet Loss
Definition: Definition:
The amount of packet loss until Route Convergence completes. The amount of packet loss produced by a Convergence Event
until Route Convergence occurs.
Discussion: Discussion:
Route Convergence Packet Loss is used to calculate the Packet loss can be observed as a reduction of forwarded
Route Convergence Time. Packet loss is an externally traffic from the maximum forwarding rate.
measurable metric.
Measurement Units: Measurement Units:
number of packets number of packets
Issues: Issues:
None None
See Also: See Also:
Route Convergence Route Convergence
Full Route Convergence Time Convergence Event
Route Convergence Event Slope Rate-Derived Convergence Time
Route Convergence Recovery Slope Loss-Derived Convergence Time
3.6 Average Route Convergence Time 3.7 Convergence Event Instant
Definition:
The time instant that a Convergence Event occurs.
Discussion:
Convergence Event Instant is observable from the data
plane as the precise time that the device under test begins
to exhibit packet loss.
Measurement Units:
hh:mm:ss:uuu
IGP Data Plane Route Convergence
Issues:
None
See Also:
Route Convergence
Convergence Event
Convergence Packet Loss
Convergence Recovery Instant
3.8 Convergence Recovery Instant
Definition:
The time instant that Route Convergence occurs.
Discussion:
Convergence Recovery Instant is observable from the data
plane as the precise time that the device under test no
longer exhibits packet loss.
Measurement Units:
hh:mm:ss:uuu
Issues:
None
See Also:
Route Convergence
Convergence Packet Loss
Convergence Event Instant
3.9 Rate-Derived Convergence Time
Definition:
The amount of time for Convergence Packet Loss to
persist upon occurrence of a Convergence Event until
occurrence of Route Convergence.
Discussion:
Rate-Derived Convergence Time can be measured as the time
difference from the Convergence Event Instant to the
Convergence Reovery Instant, as shown with Equation 1.
(eq 1) Rate-Derived Convergence Time =
Convergence Recovery Instant - Convergence Event Instant.
Rate-Derived Convergence Time can be measured at the maximum
forwarding rate.
Measurement Units:
seconds/milliseconds
IGP Data Plane Route Convergence
Issues:
None
See Also:
Route Convergence
Convergence Packet Loss
Loss-Derived Convergence Time
3.10 Loss-Derived Convergence Time
Definition: Definition:
The amount of time it takes for Route Convergence to The amount of time it takes for Route Convergence to
complete as calculated from the amount of packet loss complete as calculated from the amount of packet loss
and known forwarding rate. and known forwarding rate.
Discussion: Discussion:
Average Route Convergence Time is a metric applied to a It can be calculated from packet loss that occurs due
single router. It can be calculated from packet loss that to a Convergence Event and Route Convergence, as shown
occurs due to a network event and subsequent Route with Equation 2.
Convergence.
(eq 2) Loss-Derived Convergence Time =
Convergence Packets Loss / Forwarding Rate
NOTE: Units for this measurement are
packets / packets/second = seconds
Measurement Units: Measurement Units:
seconds/milliseconds seconds/milliseconds
Issues: Issues:
Use of Packet loss to calculate Route Convergence Time will Loss-Derived Convergence time gives a better than
give a better than actual result when converging many routes actual result when converging many routes simultaneously.
simultaneously. Full Route Convergence Time is Because of this the preferred reporting metric in most
the preferred benchmark for IGP Route Convergence. Cases is Rate-Derived Convergence Time.
See Also: See Also:
Route Convergence Route Convergence
Route Convergence Packet Loss Convergence Packet Loss
Full Route Convergence Time Rate-Derived Convergence Time
Route Convergence Event Slope Convergence Event Transition
Route Convergence Recovery Slope Convergence Recovery Transition
IGP Data Plane Route Convergence
3.7 Route Convergence Event Slope 3.11 Convergence Event Transition
Definition: Definition:
The characteristic of routers in which forwarding rate The characteristic of A router in which forwarding rate
gradually reaches zero as output queues drain after a gradually reaches zero as output queues drain after a
network event. network event.
IGP Data Plane Route Convergence
Discussion: Discussion:
Route Convergence Event Slope is externally observable. Rate-Derived Convergence Time ignores the Convergence Event
Full Route Convergence Time ignores the Route Transition. Loss-Derived Convergence Time based upon the amount
Convergence Event Slope. Average Route Convergence of packet loss takes the Convergence Event Transition into
Time based upon the amount of packet loss takes the account. The Convergence Event Transition is best observed for
Route Convergence Event Slope into account. Full Convergence.
Measurement Units: Measurement Units:
seconds/milliseconds seconds/milliseconds
Issues: Issues:
None None
See Also: See Also:
Route Convergence Route Convergence
Full Route Convergence Time
Average Route Convergence Time
Route Convergence Packet Loss
Route Convergence Recovery Slope
3.8 Route Convergence Recovery Slope Convergence Event
Rate-Derived Convergence Time
Loss-Derived Convergence Time
Convergence Packet Loss
Convergence Recovery Transition
3.12 Convergence Recovery Transition
Definition: Definition:
The characteristic of routers in which forwarding rate The characteristic of a router in which forwarding rate
gradually rises to the maximum value as many routes gradually rises to the maximum value as many routes
converge to recover from a network event. converge to recover from a network event.
Discussion: Discussion:
Route Convergence Recovery Slope is externally observable. Rate-Derived Convergence Time ignores the Route
Full Route Convergence Time ignores the Route Convergence Recovery Transition. Loss-Derived Convergence
Convergence Recovery Slope. Average Route Convergence
Time based upon the amount of packet loss takes the Time based upon the amount of packet loss takes the
Route Convergence Recovery Slope into account. Convergence Recovery Transition into account. The
Convergence Recovery Transition is best observed for Full
Convergence.
Measurement Units: Measurement Units:
seconds/milliseconds seconds/milliseconds
Issues: Issues:
None None
See Also: See Also:
Route Convergence Route Convergence
Full Route Convergence Time Rate-Derived Convergence Time
Average Route Convergence Time Loss-Derived Convergence Time
Route Convergence Packet Loss Convergence Packet Loss
Route Convergence Event Slope Convergence Event Transition
IGP Data Plane Route Convergence IGP Data Plane Route Convergence
3.9 Reroute Convergence Time 3.13 Route Convergence Time
Definition: Definition:
The amount of time it takes for Route Convergence to The amount of time it takes for Route Convergence to
complete as observed from rerouting of traffic to a complete as observed from rerouting traffic to a
new egress interface. new egress interface due to a change in next-hop without
packet loss.
Discussion: Discussion:
Reroute Convergence Time is the IGP Route Convergence Route Convergence Time is the IGP Route Convergence
benchmark to be used for network events that produce benchmark to be used for network events that produce
a change in next-hop without packet loss. An example a change in next-hop without packet loss.
of this is a cost change in which an backup path becomes
the preferred path.
Measurement Units: Measurement Units:
seconds/milliseconds seconds/milliseconds
Issues: Issues:
None None
See Also: See Also:
Route Convergence Route Convergence
Full Route Convergence Time Rate-Derived Convergence Time
Average Route Convergence Time Loss-Derived Convergence Time
3.14 Restoration Convergence Time
Definition:
The amount of time for the router under test to restore
traffic to the original outbound port after recovery from
a Convergence Event.
Discussion:
Restoration Convergence Time is the amount of time to
Converge back to the original outbound port. This is achieved
by recovering from the Convergence Event, such as restoring
the failed link. Restoration Convergence Time is measured
using the Rate-Derived Convergence Time calculation technique,
as provided in Equation 1. It is possible, but not desired
to have the Restoration Convergence Time differ from the
Rate-Derived Convergence Time.
Measurement Units:
seconds or milliseconds
Issues:
None
See Also:
Convergence Event
Rate-Derived Convegence Time
IGP Data Plane Route Convergence
3.15 Packet Sampling Interval
Definition:
The rate at which the tester (test equipment) polls to make
measurements for arriving packet flows.
Discussion:
Metrics measured at the Packet Sampling Interval include
packets received and Convergence Packet Loss.
Measurement Units:
seconds or milliseconds
Issues:
Packet Sampling Interval can influence the Convergence Graph.
This is particularly true as Full Convergence less than 1 second
is achieved. The Convergence Event Transition and Convergence
Recovery Transition can become exaggerated when the Packet
Sampling Interval is too long. This will produce a larger than
actual Rate-Derived Convergence Time. Guidelines for use of
the Packet Sampling Interval are provided in [2].
See Also:
Convergence Packet Loss
Convergence Event Transition
Convergence Recovery Transition
3.16 Local Interface
3.10 Local Interface
Definition: Definition:
An interface on the DUT. An interface on the DUT.
Discussion: Discussion:
None None
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues:
None None
See Also: See Also:
Neighbor Interface Neighbor Interface
Remote interface Remote interface
3.11 Neighbor Interface 3.17 Neighbor Interface
Definition: Definition:
The interface on the neighbor router or tester that is The interface on the neighbor router or tester that is
directly linked to the DUT's Local Interface. directly linked to the DUT's Local Interface.
Discussion: Discussion:
None None
IGP Data Plane Route Convergence
Measurement Units: Measurement Units:
N/A N/A
IGP Data Plane Route Convergence
Issues: Issues:
None None
See Also: See Also:
Local Interface Local Interface
Remote interface Remote interface
3.12 Remote Interface 3.18 Remote Interface
Definition: Definition:
An interface on a neighboring router that is not directly An interface on a neighboring router that is not directly
linked to any interface on the DUT. linked to any interface on the DUT.
Discussion: Discussion:
None None
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues:
None None
See Also: See Also:
Local interface Local interface
Neighbor Interface Neighbor Interface
3.19 Preferred Egress Interface
Definition:
The outbound interface on DUT to the preferred next-hop.
Discussion:
Preferred Egress Interface is the egress interface prior to
a Convergence Event
Measurement Units:
N/A
Issues:
None
See Also:
Next-Best Egress Interface
Convergence Event
IGP Data Plane Route Convergence
3.20 Next-Best Egress Interface
Definition:
The outbound interface on DUT to the second-best next-hop.
Discussion:
Next-Best Egress Interface is the egress interface after to
a Convergence Event
Measurement Units:
N/A
Issues:
None
See Also:
Preferred Egress Interface
Convergence Event
4. Security Considerations 4. Security Considerations
Documents of this type do not directly effect the security of Documents of this type do not directly effect the security of
the Internet or of corporate networks as long as benchmarking the Internet or of corporate networks as long as benchmarking
is not performed on devices or systems connected to operating is not performed on devices or systems connected to operating
networks. networks.
5. References 5. References
[1] Poretsky, S., "Benchmarking Applicability for IGP Data Plane [1] Poretsky, S., "Benchmarking Applicability for IGP Data Plane
Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-app-00, Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-app-01,
work in progress, June 2003. work in progress, October 2003.
[2] Poretsky, S., "Benchmarking Terminology for IGP Data Plane [2] Poretsky, S., "Benchmarking Methodology for IGP Data Plane
Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-term-00, Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-meth-01,
work in progress, June 2003. work in progress, October 2003.
[3] Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual [3] Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual
Environments", RFC 1195, December 1990. Environments", RFC 1195, December 1990.
[4] Moy, J., "OSPF Version 2", RFC 2328, IETF, April 1998. [4] Moy, J., "OSPF Version 2", RFC 2328, IETF, April 1998.
IGP Data Plane Route Convergence
6. Author's Address 6. Author's Address
Scott Poretsky Scott Poretsky
Avici Systems Quarry Technologies
101 Billerica Avenue 8 New England Executive Park
N. Billerica, MA 01862 Burlington, MA 01803
USA USA
Phone: + 1 781 395 5090
EMail: sporetsky@quarrytech.com
IGP Data Plane Route Convergence
Phone: + 1 978 964 2287 Brent Imhoff
EMail: sporetsky@avici.com WilTel Communications
3180 Rider Trail South
Bridgeton, MO 63045 USA
Phone: +1 314 595 6853
EMail: brent.imhoff@wcg.com
7. Full Copyright Statement 7. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights Copyright (C) The Internet Society (1998). All Rights
Reserved. Reserved.
This document and translations of it may be copied and This document and translations of it may be copied and
furnished to others, and derivative works that comment on or furnished to others, and derivative works that comment on or
otherwise explain it or assist in its implementation may be otherwise explain it or assist in its implementation may be
prepared, copied, published and distributed, in whole or in prepared, copied, published and distributed, in whole or in
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