draft-ietf-bmwg-igp-dataplane-conv-term-14.txt   draft-ietf-bmwg-igp-dataplane-conv-term-15.txt 
Network Working Group Network Working Group S. Poretsky
INTERNET-DRAFT Internet Draft NextPoint Networks
Intended Status: Informational Expires: August 2008
Scott Poretsky Intended Status: Informational Brent Imhoff
Reef Point Systems
Brent Imhoff
Juniper Networks Juniper Networks
November 2007 February 25, 2008
Terminology for Benchmarking Terminology for Benchmarking
Link-State IGP Data Plane Route Convergence Link-State IGP Data Plane Route Convergence
<draft-ietf-bmwg-igp-dataplane-conv-term-14.txt> <draft-ietf-bmwg-igp-dataplane-conv-term-15.txt>
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Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2008).
ABSTRACT ABSTRACT
This document describes the terminology for benchmarking Interior This document describes the terminology for benchmarking Interior
Gateway Protocol (IGP) Route Convergence. The terminology is to Gateway Protocol (IGP) Route Convergence. The terminology is to
be used for benchmarking IGP convergence time through externally be used for benchmarking IGP convergence time through externally
observable (black box) data plane measurements. The terminology observable (black box) data plane measurements. The terminology
can be applied to any link-state IGP, such as ISIS and OSPF. can be applied to any link-state IGP, such as ISIS and OSPF.
IGP Data Plane Route Convergence Link-State IGP Data Plane Route Convergence
Table of Contents Table of Contents
1. Introduction .................................................2 1. Introduction .................................................2
2. Existing definitions .........................................3 2. Existing definitions .........................................3
3. Term definitions..............................................4 3. Term definitions..............................................4
3.1 Convergence Event.........................................4 3.1 Convergence Event.........................................4
3.2 Route Convergence.........................................4 3.2 Route Convergence.........................................4
3.3 Network Convergence.......................................5 3.3 Full Convergence..........................................5
3.4 Full Convergence..........................................5 3.4 Network Convergence.......................................5
3.5 Packet Loss...............................................6 3.5 Route-Specific Convergence................................6
3.6 Convergence Packet Loss...................................6 3.6 Packet Loss...............................................6
3.7 Convergence Event Instant.................................7 3.7 Convergence Packet Loss...................................7
3.8 Convergence Recovery Instant..............................7 3.8 Convergence Event Instant.................................7
3.9 First Prefix Convergence Instant..........................8 3.9 Convergence Recovery Instant..............................8
3.10 Convergence Event Transition.............................8 3.10 First Route Convergence Instant..........................8
3.11 Convergence Recovery Transition..........................9 3.11 Convergence Event Transition.............................9
3.12 Rate-Derived Convergence Time............................9 3.12 Convergence Recovery Transition..........................9
3.13 Loss-Derived Convergence Time............................10 3.13 Rate-Derived Convergence Time............................10
3.14 Sustained Forwarding Convergence Time....................11 3.14 Loss-Derived Convergence Time............................10
3.15 First Prefix Convergence Time............................12 3.15 Route-Specific Convergence Time..........................12
3.16 Reversion Convergence Time...............................12 3.16 Sustained Convergence Validation Time....................13
3.17 Packet Sampling Interval.................................13 3.17 First Route Convergence Time.............................13
3.18 Local Interface..........................................13 3.18 Reversion Convergence Time...............................14
3.19 Neighbor Interface.......................................14 3.19 Packet Sampling Interval.................................14
3.20 Remote Interface.........................................14 3.20 Local Interface..........................................15
3.21 Preferred Egress Interface...............................15 3.21 Neighbor Interface.......................................15
3.22 Next-Best Egress Interface...............................15 3.22 Remote Interface.........................................15
3.23 Stale Forwarding.........................................15 3.23 Preferred Egress Interface...............................16
3.24 Nested Convergence Events................................16 3.24 Next-Best Egress Interface...............................16
4. IANA Considerations...........................................16 3.25 Stale Forwarding.........................................17
5. Security Considerations.......................................16 3.26 Nested Convergence Events................................17
6. Acknowledgements..............................................16 4. IANA Considerations...........................................18
7. References....................................................17 5. Security Considerations.......................................18
8. Author's Address..............................................18 6. Acknowledgements..............................................18
7. References....................................................18
8. Author's Address..............................................19
1. Introduction 1. Introduction
This draft describes the terminology for benchmarking Interior This draft describes the terminology for benchmarking Interior
Gateway Protocol (IGP) Route Convergence. The motivation and Gateway Protocol (IGP) Route Convergence. The motivation and
applicability for this benchmarking is provided in [Po07a]. The applicability for this benchmarking is provided in [Po07a]. The
methodology to be used for this benchmarking is described in [Po07m]. methodology to be used for this benchmarking is described in [Po07m].
The methodology and terminology to be used for benchmarking Route The methodology and terminology to be used for benchmarking Route
Convergence can be applied to any link-state IGP such as ISIS [Ca90] Convergence can be applied to any link-state IGP such as ISIS [Ca90]
and OSPF [Mo98]. The data plane is measured to obtain black-box and OSPF [Mo98]. The data plane is measured to obtain black-box
(externally observable) convergence benchmarking metrics. The (externally observable) convergence benchmarking metrics. The
purpose of this document is to introduce new terms required to purpose of this document is to introduce new terms required to
complete execution of the IGP Route Convergence Methodology [Po07m]. complete execution of the IGP Route Convergence Methodology [Po07m].
These terms apply to IPv4 and IPv6 traffic and IGPs. These terms apply to IPv4 and IPv6 traffic and IGPs.
IGP Data Plane Route Convergence Link-State IGP Data Plane Route Convergence
An example of Route Convergence as observed and measured from the An example of Route Convergence as observed and measured from the
data plane is shown in Figure 1. The graph in Figure 1 shows 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 Forwarding Rate versus Time. Time 0 on the X-axis is on the far
right of the graph. The Offered Load to the ingress interface of right of the graph. The Offered Load to the ingress interface of
the DUT SHOULD equal the measured maximum Throughput [Ba99][Ma98] the DUT SHOULD equal the measured maximum Throughput [Ba99][Ma98]
of the DUT and the Forwarding Rate [Ma98] is measured at the egress of the DUT and the Forwarding Rate [Ma98] is measured at the egress
interfaces of the DUT. The components of the graph and the metrics interfaces of the DUT. The components of the graph and the metrics
are defined in the Term Definitions section. are defined in the Term Definitions section.
Convergence Convergence Convergence Convergence
Recovery Event Recovery Event
Instant Instant Time = 0sec Instant Instant Time = 0sec
Forwarding Rate = ^ ^ ^ Offered Load = Forwarding Rate = ^ ^ ^ Offered Load =
Offered Load --> ------\ Packet /-------- <---Max Throughput Offered Load --> ------\ Packet /-------- <---Max Throughput
\ Loss /<----Convergence \ Loss /<----Convergence
Convergence------->\ / Event Transition Convergence------->\ / Event Transition
Recovery Transition \ / Recovery Transition \ /
\_____/<------Maximum Packet Loss \_____/<------Maximum Packet Loss
X-axis = Time ^
First Route
Convergence Instant
Y-axis = Forwarding Rate Y-axis = Forwarding Rate
X-axis = Time (increases right to left to match commercial test
equipment displays)
Figure 1. Convergence Graph Figure 1. Convergence Graph
2. Existing definitions 2. Existing definitions
This document uses existing terminology defined in other BMWG This document uses existing terminology defined in other BMWG
work. Examples include, but are not limited to: work. Examples include, but are not limited to:
Latency [Ref.[Ba91], section 3.8] Latency [Ref.[Ba91], section 3.8]
Frame Loss Rate [Ref.[Ba91], section 3.6] Frame Loss Rate [Ref.[Ba91], section 3.6]
skipping to change at page 4, line 5 skipping to change at page 4, line 5
Packet Reordering [Ref.[Mo06], section 3.3] Packet Reordering [Ref.[Mo06], section 3.3]
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 this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14, RFC 2119 document are to be interpreted as described in BCP 14, RFC 2119
[Br97]. RFC 2119 defines the use of these key words to help make the [Br97]. RFC 2119 defines the use of these key words to help make the
intent of standards track documents as clear as possible. While this intent of standards track documents as clear as possible. While this
document uses these keywords, this document is not a standards track document uses these keywords, this document is not a standards track
document. document.
IGP Data Plane Route Convergence Link-State IGP Data Plane Route Convergence
3. Term Definitions 3. Term Definitions
3.1 Convergence Event 3.1 Convergence Event
Definition: Definition:
The occurrence of a planned or unplanned action in the network The occurrence of a planned or unplanned event in the network
that results in a change in the egress interface of the Device that results in a change in the egress interface of the Device
Under Test (DUT) for routed packets. Under Test (DUT) for routed packets.
Discussion: Discussion:
Convergence Events include link loss, routing protocol session Convergence Events include link loss, routing protocol session
loss, router failure, configuration change, and better next-hop loss, router failure, configuration change, and better next-hop
learned via a routing protocol. learned via a routing protocol.
Measurement Units: Measurement Units:
N/A N/A
skipping to change at page 4, line 33 skipping to change at page 4, line 33
Issues: Issues:
None None
See Also: See Also:
Convergence Packet Loss Convergence Packet Loss
Convergence Event Instant Convergence Event Instant
3.2 Route Convergence 3.2 Route Convergence
Definition: Definition:
Route Convergence is the action to update all components of the The action to update all components of the router with the
router with the most recent route change(s) including the most recent route change(s) including the Routing
Routing Information Base (RIB) and Forwarding Information Base Information Base (RIB) and Forwarding Information Base (FIB),
(FIB), along with software and hardware tables, such that along with software and hardware tables, such that forwarding
forwarding is successful for one or more destinations. is successful for one or more route entries.
Discussion: Discussion:
Route Convergence MUST occur after a Convergence Event. Route Convergence MUST occur after a Convergence Event.
Route Convergence can be observed externally by the rerouting Route Convergence can be observed externally by the rerouting
of data traffic to the Next-best Egress Interface. Also, of data traffic to the Next-best Egress Interface. Also,
Route Convergence may or may not be sustained over time. completion of Route Convergence may or may not be sustained
over time.
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues:
None None
See Also: See Also:
Network Convergence Network Convergence
Full Convergence Full Convergence
Convergence Event Convergence Event
IGP Data Plane Route Convergence Link-State IGP Data Plane Route Convergence
3.3 Network Convergence 3.3 Full Convergence
Definition: Definition:
The completion of updating of all routing tables, including Route Convergence for an entire FIB in which complete recovery
from the Convergence Event is indicated by the DUT Throughput
equal to the offered load.
Discussion:
When benchmarking convergence, it is useful to measure
the time to converge an entire FIB. For example,
a Convergence Event can be produced for an OSPF table of
5000 routes so that the time to converge routes 1 through
5000 is measured. Completion of Full Convergence is externally
observable from the data plane when the Throughput of the data
plane traffic on the Next-Best Egress Interface equals the
offered load. Full Convergence may or may not be sustained over
time. The Sustained Convergence Validation Time MUST be
applied.
Measurement Units:
N/A
Issues:
None
See Also:
Network Convergence
Route Convergence
Convergence Event
3.4 Network Convergence
Definition:
The process of updating of all routing tables, including
distributed FIBs, in all routers throughout the network. distributed FIBs, in all routers throughout the network.
Discussion: Discussion:
Network Convergence requires completion of all Route Network Convergence requires completion of all Route
Convergenceoperations for all routers in the network following Convergenceoperations for all routers in the network following
a Convergence Event. Network Convergence can be observed by a Convergence Event. Completion of Network Convergence can be
recovery of System Under Test (SUT) Throughput to equal the observed by recovery of System Under Test (SUT) Throughput to
offered load, with no Stale Forwarding, and no Blenders equal the offered load, with no Stale Forwarding, and no
[Ca01][Ci03]. Blenders [Ca01][Ci03].
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues:
None None
See Also: See Also:
Route Convergence Route Convergence
Stale Forwarding Stale Forwarding
Link-State IGP Data Plane Route Convergence
3.4 Full Convergence 3.5 Route-Specific Convergence
Definition: Definition:
Route Convergence for an entire FIB in which complete recovery Route Convergence for one or more specific route entries in
from the Convergence Event is indicated by the DUT Throughput the FIB in which recovery from the Convergence Event is
equal to the offered load. indicated by data-plane traffic for a flow [Po06] matching that
route entry(ies) being routed to the Next-Best Egress Interface.
Discussion: Discussion:
When benchmarking convergence, it is useful to measure When benchmarking convergence, it is sometimes useful to
the time to converge an entire FIB. For example, measure the time to converge a single flow [Po06] or group of
a Convergence Event can be produced for an OSPF table of flows to benchmark convergence time for one or a few route
5000 routes so that the time to converge routes 1 through entries in the FIB instead of the entire FIB. Route-Specific
5000 is measured. Full Convergence is externally observable Convergence of a flow is externally observable from the data
from the data plane when the Throughput of the data plane when the data plane traffic for that flow is routed to
plane traffic on the Next-Best Egress Interface equals the the Next-Best Egress Interface.
offered load.
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues:
None None
See Also: See Also:
Network Convergence Full Convergence
Route Convergence Route Convergence
Convergence Event Convergence Event
IGP Data Plane Route Convergence
3.5 Packet Loss 3.6 Packet Loss
Definition: Definition:
The number of packets that should have been forwarded The number of packets that should have been forwarded
by a DUT under a constant offered load that were by a DUT under a constant offered load that were
not forwarded due to lack of resources. not forwarded due to lack of resources.
Discussion: Discussion:
Packet Loss is a modified version of the term "Frame Loss Rate" Packet Lss is a modified version of the term "Frame Loss Rate"
as defined in [Ba91]. The term "Frame Loss" is intended for as defined in [Ba91]. The term "Frame Loss" is intended for
Ethernet Frames while "Packet Loss" is intended for IP packets. Ethernet Frames while "Packet Loss" is intended for IP packets.
Packet Loss can be measured as a reduction in forwarded traffic Packet Loss can be measured as a reduction in forwarded traffic
from the Throughput [Ba91] of the DUT. from the Throughput [Ba91] of the DUT.
Measurement units: Measurement units:
Number of offered packets that are not forwarded. Number of offered packets that are not forwarded.
Issues: None Issues: None
See Also: See Also:
Convergence Packet Loss Convergence Packet Loss
Link-State IGP Data Plane Route Convergence
3.6 Convergence Packet Loss 3.7 Convergence Packet Loss
Definition: Definition:
The number of packets lost due to a Convergence Event The number of packets lost due to a Convergence Event
until Full Convergence occurs. until Full Convergence completes.
Discussion: Discussion:
Convergence Packet Loss includes packets that were lost and Convergence Packet Loss includes packets that were lost and
packets that were delayed due to buffering. The Convergence packets that were delayed due to buffering. The Convergence
Packet Loss observed in a Packet Sampling Interval may or may Packet Loss observed in a Packet Sampling Interval may or may
not be equal to the number of packets in the offered load not be equal to the number of packets in the offered load
during the interval following a Convergence Event (see Figure during the interval following a Convergence Event (see Figure
1). 1).
Measurement Units: Measurement Units:
number of packets number of packets
Issues: None Issues: None
See Also: See Also:
Packet Loss Packet Loss
Route Convergence Route Convergence
Convergence Event Convergence Event
Packet Sampling Interval Packet Sampling Interval
IGP Data Plane Route Convergence
3.7 Convergence Event Instant 3.8 Convergence Event Instant
Definition: Definition:
The time instant that a Convergence Event becomes observable in The time instant that a Convergence Event becomes observable in
the data plane. the data plane.
Discussion: Discussion:
Convergence Event Instant is observable from the data Convergence Event Instant is observable from the data
plane as the precise time that the device under test begins plane as the precise time that the device under test begins
to exhibit packet loss. to exhibit packet loss.
skipping to change at page 7, line 28 skipping to change at page 8, line 4
hh:mm:ss:nnn:uuu, hh:mm:ss:nnn:uuu,
where 'nnn' is milliseconds and 'uuu' is microseconds. where 'nnn' is milliseconds and 'uuu' is microseconds.
Issues: Issues:
None None
See Also: See Also:
Convergence Event Convergence Event
Convergence Packet Loss Convergence Packet Loss
Convergence Recovery Instant Convergence Recovery Instant
Link-State IGP Data Plane Route Convergence
3.8 Convergence Recovery Instant 3.9 Convergence Recovery Instant
Definition: Definition:
The time instant that Full Convergence is measured The time instant that Full Convergence completion is
and then maintained for an interval of duration equal to measured and then maintained for an interval of duration
the Sustained Forwarding Convergence Time equal to the Sustained Convergence Validation Time.
Discussion: Discussion:
Convergence Recovery Instant is measurable from the data Convergence Recovery Instant is measurable from the data
plane as the precise time that the device under test plane as the precise time that the device under test
achieves Full Convergence. completes Full Convergence.
Measurement Units: Measurement Units:
hh:mm:ss:nnn:uuu, hh:mm:ss:nnn:uuu,
where 'nnn' is milliseconds and 'uuu' is microseconds. where 'nnn' is milliseconds and 'uuu' is microseconds.
Issues: Issues:
None None
See Also: See Also:
Sustained Forwarding Convergence Time Sustained Convergence Validation Time
Convergence Packet Loss Convergence Packet Loss
Convergence Event Instant Convergence Event Instant
IGP Data Plane Route Convergence
3.9 First Prefix Convergence Instant 3.10 First Route Convergence Instant
Definition: Definition:
The time instant for convergence of a first route entry The time instant a first route entry has converged
following a Convergence Event, as observed by receipt of following a Convergence Event, as observed by receipt of
the first packet from the Next-Best Egress Interface. the first packet from the Next-Best Egress Interface.
Discussion: Discussion:
The First Prefix Convergence Instant is an indication that the The First Route Convergence Instant is an indication that the
process to achieve Full Convergence has begun. Any route may be process to achieve Full Convergence has begun. Any route may
the first to converge for First Convergence. Measurement on the be the first to converge for First Route Convergence Instant.
data-plane enables First Convergence to be observed without any Measurement on the data-plane enables the First Route
white-box information from the DUT. Convergence Instant to be observed without any white-box
information from the DUT.
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues:
None None
See Also: See Also:
Route Convergence Route Convergence
Full Convergence Full Convergence
Stale Forwarding Stale Forwarding
Link-State IGP Data Plane Route Convergence
3.10 Convergence Event Transition 3.11 Convergence Event Transition
Definition: Definition:
A time interval observed following a Convergence Event in which A time interval observed following a Convergence Event in which
Throughput gradually reduces to zero. Throughput gradually reduces to a minimum value.
Discussion: Discussion:
The Convergence Event Transition is best observed for Full The Convergence Event Transition is best observed for Full
Convergence. The egress packet rate observed during a Convergence. The egress packet rate observed during a
Convergence Event Transition may not decrease linearly. Both Convergence Event Transition may not decrease linearly and may
the offered load and the Packet Sampling Interval influence the not decrease to zero. Both the offered load and the Packet
observations of the Convergence Event Transition. For example, Sampling Interval influence the observations of the Convergence
even if the Convergence Event were to cause the Throughput Event Transition. For example, even if the Convergence Event
[Ba91] to drop to zero there would be some number of packets were to cause the Throughput [Ba91] to drop to zero there would
observed, unless the Packet Sampling Interval is exactly be some number of packets observed, unless the Packet Sampling
aligned with the Convergence Event. This is further discussed Interval is exactly aligned with the Convergence Event. This
with the term "Packet Sampling Interval". is further discussed with the term "Packet Sampling Interval".
IGP Data Plane Route Convergence
Measurement Units: Measurement Units:
seconds seconds
Issues: Issues:
None None
See Also: See Also:
Convergence Event Convergence Event
Full Convergence Full Convergence
Packet Sampling Interval Packet Sampling Interval
3.11 Convergence Recovery Transition 3.12 Convergence Recovery Transition
Definition: Definition:
The characteristic of the DUT in which Throughput gradually The characteristic of the DUT in which Throughput gradually
increases to equal the offered load. increases to equal the offered load.
Discussion: Discussion:
The Convergence Recovery Transition is best observed for The Convergence Recovery Transition is best observed for
Full Convergence. The egress packet rate observed during Full Convergence. The egress packet rate observed during
a Convergence Recovery Transition may not increase linearly. a Convergence Recovery Transition may not increase linearly.
Both the offered load and the Packet Sampling Interval Both the offered load and the Packet Sampling Interval
skipping to change at page 9, line 41 skipping to change at page 10, line 4
"Packet Sampling Interval". "Packet Sampling Interval".
Measurement Units: Measurement Units:
seconds seconds
Issues: None Issues: None
See Also: See Also:
Full Convergence Full Convergence
Packet Sampling Interval Packet Sampling Interval
Link-State IGP Data Plane Route Convergence
3.12 Rate-Derived Convergence Time 3.13 Rate-Derived Convergence Time
Definition: Definition:
The amount of time for Convergence Packet Loss to persist upon The amount of time for Convergence Packet Loss to persist upon
occurrence of a Convergence Event until measurement of Full occurrence of a Convergence Event until Full Convergence has
Convergence. completed.
Rate-Derived Convergence Time can be measured as the time Rate-Derived Convergence Time can be measured as the time
difference from the Convergence Event Instant to the difference from the Convergence Event Instant to the
Convergence Recovery Instant, as shown with Equation 1. Convergence Recovery Instant, as shown with Equation 1.
(Equation 1) (Equation 1)
Rate-Derived Convergence Time = Rate-Derived Convergence Time =
Convergence Recovery Instant - Convergence Event Instant. Convergence Recovery Instant - Convergence Event Instant.
IGP Data Plane Route Convergence
Discussion: Discussion:
Rate-Derived Convergence Time should be measured at the maximum Rate-Derived Convergence Time SHOULD be measured at the maximum
Throughput of the DUT. At least one packet per route in the FIB Throughput of the DUT. At least one packet per route in the FIB
for all routes in the FIB MUST be offered to the DUT per second. for all routes in the FIB MUST be offered to the DUT within the
Packet Sampling Interval.
Failure to achieve Full Convergence results in a Rate-Derived Failure to achieve Full Convergence results in a Rate-Derived
Convergence Time benchmark of infinity. Convergence Time benchmark of infinity. It is RECOMMENDED that
the Rate-Derived Convergence Time be measured when benchmarking
Full Convergence.
Measurement Units: Measurement Units:
seconds seconds
Issues: Issues: None
None
See Also: See Also:
Convergence Packet Loss Convergence Packet Loss
Convergence Recovery Instant Convergence Recovery Instant
Convergence Event Instant Convergence Event Instant
Full Convergence Full Convergence
3.13 Loss-Derived Convergence Time 3.14 Loss-Derived Convergence Time
Definition: Definition:
The amount of time it takes for Full Convergence to be The amount of time it takes for Full Convergence to be
achieved as calculated from the amount of Convergence completed as calculated from the amount of Convergence
Packet Loss. Loss-Derived Convergence Time can be Packet Loss. Loss-Derived Convergence Time can be
calculated from Convergence Packet Loss that occurs due calculated from Convergence Packet Loss as shown with
to a Convergence Event and Route Convergence as shown Equation 2.
with Equation 2.
Equation 2 - Equation 2 -
Loss-Derived Convergence Time = Loss-Derived Convergence Time =
Convergence Packets Loss / Offered Load Convergence Packets Loss / Offered Load
NOTE: Units for this measurement are where units are packets / packets/second = seconds
packets / packets/second = seconds Link-State IGP Data Plane Route Convergence
Discussion: Discussion:
Loss-Derived Convergence Time gives a better than Optimally, the Convergence Event Transition and Convergence
actual result when converging many routes simultaneously.
Rate-Derived Convergence Time takes the Convergence Recovery
Transition into account, but Loss-Derived Convergence Time
ignores the Route Convergence Recovery Transition because
it is obtained from the measured Convergence Packet Loss.
Ideally, the Convergence Event Transition and Convergence
Recovery Transition are instantaneous so that the Recovery Transition are instantaneous so that the
Rate-Derived Convergence Time = Loss-Derived Convergence Time. Rate-Derived Convergence Time = Loss-Derived Convergence Time.
However, router implementations are less than ideal. However, router implementations are less than ideal.
For these reasons the preferred reporting benchmark for IGP Loss-Derived Convergence Time gives a better than
Route Convergence is the Rate-Derived Convergence Time. actual result when converging many routes simultaneously
because it ignores the Convergence Recovery Transition.
Rate-Derived Convergence Time takes the Convergence Recovery
Transition into account. Equation 2 calculates the average
convergence time over all routes to which packets have been
sent. Since this average convergence time is in general
smaller than the maximum convergence time over all routes,
Loss-Derived Convergence Time is not the preferred metric to
indicate Full Convergence completion. For this reason the
RECOMMENDED benchmark metric for Full Convergence is the
Rate-Derived Convergence Time.
Guidelines for reporting Loss-Derived Convergence Time are Guidelines for reporting Loss-Derived Convergence Time are
provided in [Po07m]. provided in [Po07m].
IGP Data Plane Route Convergence
Measurement Units: Measurement Units:
seconds seconds
Issues: Issues:
None None
See Also: See Also:
Convergence Event Convergence Event
Convergence Packet Loss Convergence Packet Loss
Rate-Derived Convergence Time Rate-Derived Convergence Time
Route-Specific Convergence
Convergence Event Transition Convergence Event Transition
Convergence Recovery Transition Convergence Recovery Transition
Link-State IGP Data Plane Route Convergence
3.14 Sustained Forwarding Convergence Time 3.15 Route-Specific Convergence Time
Definition: Definition:
The amount of time for which Full Convergence is maintained The amount of time it takes for Route-Specific Convergence to
without additional packet loss. be completed as calculated from the amount of Convergence
Packet Loss per flow.
Discussion: Route-Specific Convergence Time can be calculated from
The purpose of the Sustained Forwarding Convergence Time is to Convergence Packet Loss as shown with Equation 3.
produce Convergence benchmarks protected against fluctuation
in Throughput after Full Convergence is observed. The
Sustained Forwarding Convergence Time to be used is calculated
as shown in Equation 3.
Equation 3 - Equation 3 -
Sustained Forwarding Convergence Time = Route-Specific Convergence Time =
C*(Convergence Packet Loss/Offered Load) Convergence Packets Loss / Offered Load
where units are packets / packets/second = seconds
where, Discussion:
a. units are packets/pps = sec and
b. C is a constant. The RECOMMENDED value for C is 5 as It is possible to provide an offered load that has flows
selected from working group consensus. This is similar matching every route entry in the FIB and benchmarking
to RFC 2544 [Ba99] which recommends waiting 2 seconds for Route-Specific Convergence Time for all route entries. The
residual frames to arrive and 5 seconds for DUT number of flows that can be measured is dependent upon the flow
restabilization. measurement capabilities of the Tester. When benchmarking
Route-Specific Convergence, Convergence Packet Loss is measured
for specific flow(s) and Equation 3 is applied for each flow.
Each flow has a single destination address matching a different
route entry. The fastest measurable convergence time is equal
to the time between two consecutive packets of a flow offered
by the Tester.
c. at least one packet per route in the FIB for all The Route-Specific Convergence Time benchmarks enable minimum,
routes in the FIB MUST be offered to the DUT per second. maximum, average, and median convergence time measurements to be
reported by comparing the results for the different route
entries. It also enables benchmarking of convergence time when
configuring a priority value for route entry(ies). Since
multiple Route-Specific Convergence Times can be measured it is
possible to have an array of results. The format for reporting
Route-Specific Convergence Time is provided in [Po07m].
The Route-Specific Convergence Time MAY be used to benchmark
Full Convergence when used in combination with many flows
matching every FIB entry.
Measurement Units: Measurement Units:
seconds seconds
Issues: None Issues:
None
See Also: See Also:
Full Convergence Convergence Event
Convergence Recovery Instant Convergence Packet Loss
IGP Data Plane Route Convergence Route-Specific Convergence
Link-State IGP Data Plane Route Convergence
3.15 First Prefix Convergence Time 3.16 First Route Convergence Time
Definition: Definition:
The amount of time for Convergence Packet Loss until the The amount of time for Convergence Packet Loss until the
convergence of a first route entry on the Next-Best Egress convergence of a first route entry on the Next-Best Egress
Interface, as indicated by the First Prefix Convergence Interface, as indicated by the First Route Convergence
Instant. Instant.
First Prefix Convergence Time can be measured as the time Discussion:
The First Route Convergence Time benchmarking metric can be
measured when benchmarking either Full Convergence or
Route-Specific Convergence. When benchmarking Full Convergence,
First Route Convergence Time can be measured as the time
difference from the Convergence Event Instant and the First difference from the Convergence Event Instant and the First
Prefix Convergence Instant, as shown with Equation 4. Route Convergence Instant, as shown with Equation 4a.
(Equation 4) (Equation 4a)
First Prefix Convergence Time = First Route Convergence Time =
First Prefix Convergence Instant - First Route Convergence Instant - Convergence Event Instant
Convergence Event Instant.
Discussion: When benchmarking Route-Specific Convergence, First Route
First Prefix Convergence Time should be measured at the maximum Convergence Time can be measured as the minimum Route-Specific
Convergence Time, as shown with Equation 4b.
(Equation 4b)
First Route Convergence Time =
min(Route-Specific Convergence Time)
First Route Convergence Time should be measured at the maximum
Throughput of the DUT. At least one packet per route in the FIB Throughput of the DUT. At least one packet per route in the FIB
for all routes in the FIB MUST be offered to the DUT per second. for all routes in the FIB MUST be offered to the DUT within the
Failure to achieve the First Prefix Convergence Instant results Packet Sampling Interval. Failure to achieve the First Route
in a First Prefix Convergence Time benchmark of infinity. Convergence Instant results in a First Route Convergence Time
benchmark of infinity.
Measurement Units: Measurement Units:
hh:mm:ss:nnn:uuu, seconds
where 'nnn' is milliseconds and 'uuu' is microseconds.
Issues: Issues: None
None
See Also: See Also:
Convergence Packet Loss Convergence Packet Loss
First Prefix Convergence Instant First Route Convergence Instant
3.16 Reversion Convergence Time 3.17 Sustained Convergence Validation Time
Definition: Definition:
The amount of time for the DUT to forward traffic from the The amount of time for which the completion of Full
Preferred Egress Interface, instead of the Next-Best Egress Convergence is maintained without additional packet loss.
Interface, upon recovery from a Convergence Event.
Link-State IGP Data Plane Route Convergence
Discussion: Discussion:
Reversion Convergence Time is the amount of time for routes The purpose of the Sustained Convergence Validation Time is to
to converge to the original outbound port. This is achieved produce Convergence benchmarks protected against fluctuation
by recovering from the Convergence Event, such as restoring in Throughput after the completion of Full Convergence is
the failed link. Reversion Convergence Time is measured observed. The RECOMMENDED Sustained Convergence Validation
using the Rate-Derived Convergence Time calculation technique, Time to be used is 5 seconds.
as provided in Equation 1. It is possible to have the
Reversion Convergence Time differ from the Rate-Derived
Convergence Time.
IGP Data Plane Route Convergence Measurement Units:
seconds
Issues: None
See Also:
Full Convergence
Convergence Recovery Instant
3.18 Reversion Convergence Time
Definition:
The amount of time for the DUT to complete Full Convergence
to the Preferred Egress Interface, instead of the Next-Best
Egress Interface, upon recovery from a Convergence Event.
Discussion:
Reversion Convergence Time is the amount of time for Full
COnvergence to the original egress interface. This is
achieved by recovering from the Convergence Event, such as
restoring the failed link. Reversion Convergence Time is
measured using the Rate-Derived Convergence Time calculation
technique, as provided in Equation 1. It is possible to have
the Reversion Convergence Time differ from the Rate-Derived
Convergence Time.
Measurement Units: Measurement Units:
seconds seconds
Issues: Issues: None
None
See Also: See Also:
Preferred Egress Interface Preferred Egress Interface
Convergence Event Convergence Event
Rate-Derived Convergence Time Rate-Derived Convergence Time
3.17 Packet Sampling Interval 3.19 Packet Sampling Interval
Definition: Definition:
The interval at which the tester (test equipment) polls to make The interval at which the tester (test equipment) polls to make
measurements for arriving packet flows. measurements for arriving packet flows.
Discussion: Discussion:
Metrics measured at the Packet Sampling Interval MUST include At least one packet per route in the FIB
Forwarding Rate and Convergence Packet Loss. for all routes in the FIB MUST be offered to the DUT within the
Packet Sampling Interval. Metrics measured at the Packet
Sampling Interval MUST include Forwarding Rate and Convergence
Packet Loss.
Link-State IGP Data Plane Route Convergence
Measurement Units: Measurement Units:
seconds seconds
Issues: Issues:
Packet Sampling Interval can influence the Convergence Graph. Packet Sampling Interval can influence the Convergence Graph.
This is particularly true when implementations achieve Full This is particularly true when implementations complete Full
Convergence in less than 1 second. The Convergence Event Convergence in less than the Packet Sampling Interval. The
Transition and Convergence Recovery Transition can become Convergence Event Transition and Convergence Recovery Transition
exaggerated when the Packet Sampling Interval is too long. can become exaggerated when the Packet Sampling Interval is too
This will produce a larger than actual Rate-Derived long. This will produce a larger than actual Rate-Derived
Convergence Time. The recommended value for configuration Convergence Time. The recommended value for configuration of
of the Packet Sampling Interval is provided in [Po07m]. the Packet Sampling Interval is provided in [Po07m].
See Also: See Also:
Convergence Packet Loss Convergence Packet Loss
Convergence Event Transition Convergence Event Transition
Convergence Recovery Transition Convergence Recovery Transition
3.18 Local Interface 3.20 Local Interface
Definition: Definition:
An interface on the DUT. An interface on the DUT.
Discussion: Discussion:
A failure of the Local Interface indicates that the failure A failure of the Local Interface indicates that the failure
occured directly on the DUT. occurred directly on the DUT.
IGP Data Plane Route Convergence
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues:
None None
See Also: See Also:
Neighbor Interface Neighbor Interface
Remote Interface Remote Interface
3.19 Neighbor Interface 3.21 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 A failure of a Neighbor Interface indicates that a
failure occurred on a neighbor router's interface that
directly links the neighbor router to the DUT.
Measurement Units: Measurement Units:
N/A N/A
Link-State IGP Data Plane Route Convergence
Issues: Issues:
None None
See Also: See Also:
Local Interface Local Interface
Remote Interface Remote Interface
3.20 Remote Interface 3.22 Remote Interface
Definition: Definition:
An interface on a neighboring router that is not directly An interface on a neighboring router that is not directly
connected to any interface on the DUT. connected to any interface on the DUT.
Discussion: Discussion:
A failure of a Remote Interface indicates that the failure A failure of a Remote Interface indicates that the failure
occurred on an interface that is not directly connected occurred on a neighbor router's interface that is not
to the DUT. directly connected to the DUT.
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues:
None None
See Also: See Also:
Local Interface Local Interface
Neighbor Interface Neighbor Interface
IGP Data Plane Route Convergence
3.21 Preferred Egress Interface 3.23 Preferred Egress Interface
Definition: Definition:
The outbound interface from the DUT for traffic routed to the The outbound interface from the DUT for traffic routed to the
preferred next-hop. preferred next-hop.
Discussion: Discussion:
The Preferred Egress Interface is the egress interface prior The Preferred Egress Interface is the egress interface prior
to a Convergence Event. to a Convergence Event.
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues:
None None
See Also: See Also:
Next-Best Egress Interface Next-Best Egress Interface
3.22 Next-Best Egress Interface 3.24 Next-Best Egress Interface
Definition: Definition:
The outbound interface from the DUT for traffic routed to the The outbound interface from the DUT for traffic routed to the
second-best next-hop. It is the same media type and link speed second-best next-hop. It is the same media type and link speed
as the Preferred Egress Interface as the Preferred Egress Interface
Link-State IGP Data Plane Route Convergence
Discussion: Discussion:
The Next-Best Egress Interface becomes the egress interface The Next-Best Egress Interface becomes the egress interface
after a Convergence Event. after a Convergence Event.
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues: None
None
See Also: See Also:
Preferred Egress Interface Preferred Egress Interface
3.23 Stale Forwarding 3.25 Stale Forwarding
Definition: Definition:
Forwarding of traffic to route entries that no longer exist Forwarding of traffic to route entries that no longer exist
or to route entries with next-hops that are no longer preferred. or to route entries with next-hops that are no longer preferred.
Discussion: Discussion:
Stale Forwarding can be caused by a Convergence Event and is Stale Forwarding can be caused by a Convergence Event and can
also known as a "black-hole" or microloop since it may produce manifest as a "black-hole" or microloop that produces packet
packet loss. Stale Forwarding exists until Network Convergence loss. Stale Forwarding can exist until Network Convergence is
is achieved. completed. Stale Forwarding cannot be observed with a single
DUT.
IGP Data Plane Route Convergence
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues: None
None
See Also: See Also:
Network Convergence Network Convergence
3.24 Nested Convergence Events 3.26 Nested Convergence Events
Definition: Definition:
The occurrence of a Convergence Event while the route The occurrence of a Convergence Event while the route
table is converging from a prior Convergence Event. table is converging from a prior Convergence Event.
Discussion: Discussion:
The Convergence Events for a Nested Convergence Event The Convergence Events for a Nested Convergence Event
MUST occur with different neighbors. A common MUST occur with different neighbors. A common
observation from a Nested Convergence Event will be observation from a Nested Convergence Event will be
the withdrawal of routes from one neighbor while the the withdrawal of routes from one neighbor while the
routes of another neighbor are being installed. routes of another neighbor are being installed.
Measurement Units: Measurement Units:
N/A N/A
Issues: Issues: None
None
See Also: See Also:
Convergence Event Convergence Event
Link-State IGP Data Plane Route Convergence
4. IANA Considerations 4. IANA Considerations
This document requires no IANA considerations. This document requires no IANA considerations.
5. Security Considerations 5. Security Considerations
Documents of this type do not directly affect the security of Documents of this type do not directly affect the security of
Internet or corporate networks as long as benchmarking Internet or corporate networks as long as benchmarking
is not performed on devices or systems connected to production is not performed on devices or systems connected to production
networks. networks.
6. Acknowledgements 6. Acknowledgements
Thanks to Sue Hares, Al Morton, Kevin Dubray, Ron Bonica, David Ward, Thanks to Sue Hares, Al Morton, Kevin Dubray, Ron Bonica, David Ward,
and the BMWG for their contributions to this work. Kris Michielsen and the BMWG for their contributions to this work.
IGP Data Plane Route Convergence
7. References 7. References
7.1 Normative References 7.1 Normative References
[Ba91] Bradner, S. "Benchmarking Terminology for Network [Ba91] Bradner, S. "Benchmarking Terminology for Network
Interconnection Devices", RFC1242, July 1991. Interconnection Devices", RFC1242, July 1991.
[Ba99] Bradner, S. and McQuaid, J., "Benchmarking [Ba99] Bradner, S. and McQuaid, J., "Benchmarking
Methodology for Network Interconnect Devices", Methodology for Network Interconnect Devices",
RFC 2544, March 1999. RFC 2544, March 1999.
skipping to change at page 17, line 35 skipping to change at page 18, line 49
[Mo06] Morton, A., et al, "Packet Reordering Metrics", RFC 4737, [Mo06] Morton, A., et al, "Packet Reordering Metrics", RFC 4737,
November 2006. November 2006.
[Po06] Poretsky, S., et al., "Terminology for Benchmarking [Po06] Poretsky, S., et al., "Terminology for Benchmarking
Network-layer Traffic Control Mechanisms", RFC 4689, Network-layer Traffic Control Mechanisms", RFC 4689,
November 2006. November 2006.
[Po07a] Poretsky, S., "Benchmarking Applicability for Link-State [Po07a] Poretsky, S., "Benchmarking Applicability for Link-State
IGP Data Plane Route Convergence", IGP Data Plane Route Convergence",
draft-ietf-bmwg-igp-dataplane-conv-app-14, work in progress, draft-ietf-bmwg-igp-dataplane-conv-app-15, work in progress,
November 2007. February 2008.
Link-State IGP Data Plane Route Convergence
[Po07m] Poretsky, S. and Imhoff, B., "Benchmarking Methodology for [Po07m] Poretsky, S. and Imhoff, B., "Benchmarking Methodology for
Link-State IGP Data Plane Route Convergence", Link-State IGP Data Plane Route Convergence",
draft-ietf-bmwg-igp-dataplane-conv-meth-14, work in progress, draft-ietf-bmwg-igp-dataplane-conv-meth-15, work in progress,
November 2007. February 2008.
7.2 Informative References 7.2 Informative References
[Ca01] S. Casner, C. Alaettinoglu, and C. Kuan, "A Fine-Grained View [Ca01] S. Casner, C. Alaettinoglu, and C. Kuan, "A Fine-Grained View
of High Performance Networking", NANOG 22, June 2001. of High Performance Networking", NANOG 22, June 2001.
[Ci03] L. Ciavattone, A. Morton, and G. Ramachandran, "Standardized [Ci03] L. Ciavattone, A. Morton, and G. Ramachandran, "Standardized
Active Measurements on a Tier 1 IP Backbone", IEEE Active Measurements on a Tier 1 IP Backbone", IEEE
Communications Magazine, pp90-97, May 2003. Communications Magazine, pp90-97, May 2003.
IGP Data Plane Route Convergence
8. Author's Address 8. Author's Address
Scott Poretsky Scott Poretsky
Reef Point Systems NextPoint Networks
3 Federal Street 3 Federal Street
Billerica, MA 01821 Billerica, MA 01821
USA USA
Phone: + 1 508 439 9008 Phone: + 1 508 439 9008
EMail: sporetsky@reefpoint.com EMail: sporetsky@nextpointnetworks.com
Brent Imhoff Brent Imhoff
Juniper Networks Juniper Networks
1194 North Mathilda Ave 1194 North Mathilda Ave
Sunnyvale, CA 94089 Sunnyvale, CA 94089
USA USA
Phone: + 1 314 378 2571 Phone: + 1 314 378 2571
EMail: bimhoff@planetspork.com EMail: bimhoff@planetspork.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided This document and the information contained herein are provided
on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
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Link-State IGP Data Plane Route Convergence
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IGP Data Plane Route Convergence
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