Network Working Group
INTERNET-DRAFT
Expires in: December 2003
Scott Poretsky
Avici Systems
June 2003
Terminology for Benchmarking
IGP Data Plane Route Convergence
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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Table of Contents
1. Introduction ...............................................2
2. Existing definitions .......................................2
3. Term definitions............................................2
3.1 Network Convergence.....................................2
3.2 Protocol Convergence....................................3
3.3 Route Convergence.......................................3
3.4 Full Route Convergence Time.............................4
3.5 Route Convergence Packet Loss...........................5
3.6 Average Route Convergence Time..........................5
3.7 Route Convergence Event Slope...........................6
3.8 Route Convergence Recovery Slope........................6
3.9 Reroute Convergence Time...............................7
3.10 Local Interface........................................7
3.11 Neighbor Interface.....................................8
3.12 Remote Interface.......................................8
4. Security Considerations.....................................8
5. References..................................................9
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IGP Route Convergence
7. Author's Address............................................9
8. Full Copyright Statement....................................9
1. Introduction
This draft describes the terminology for benchmarking IGP Route
Convergence. The motivation and applicability for this
benchmarking is provided in [1]. The methodology to be used for
this benchmarking is described in [2]. The methodology and
terminology to be used for benchmarking route convergence can be
applied to any link-state IGP such as ISIS [3] and OSPF [4]. The
data plane is measured to obtain the convergence benchmarking metrics.
The purpose of this document is to introduce new terms required to
complete execution of the IGP Route Convergence Methodology [2].
2. Existing definitions
For the sake of clarity and continuity this RFC adopts the template
for definitions set out in Section 2 of RFC 1242. Definitions are
indexed and grouped together in sections for ease of reference.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC 2119.
3. Term definitions
3.1 Network Convergence
Definition:
The completion of updating of all routing tables, including the
FIB, in all routers throughout the network.
Discussion:
Network Convergence can be approximated to the sum of Route
Convergence for all routers in the network. Network Convergence
can only be determined by the occurrence of packet loss or stale
forwarding due to an out-of-date FIB.
Measurement Units:
Converged or Not Converged
Issues:
None
See Also:
Protocol Convergence
Route Convergence
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3.2 Protocol Convergence
Definition:
The completion of updating a router's RIB and the forwarding of
an route update message (LSA for OSPF/LSP for ISIS) to a
neighboring peer.
Discussion:
Protocol Convergence considers only the Control Plane. IGP
messaging is used to verify and measure convergence. Updating
of the FIB, hardware updating, rerouting of traffic, and packet
loss are not considered.
Measurement Units:
LSA/LSP Transmitted or LSA/LSP Not Transmitted.
Issues:
Protocol Convergence does not consider updating of the FIB,
hardware updating, rerouting of traffic, and resultant packet
loss. Protocol Convergence is only a partial measurement of
Route Convergence.
See Also:
Network Convergence
Route Convergence
3.3 Route Convergence
Definition:
The completion of the router's FIB becoming fully converged.
Discussion:
All components of the router have been updated with the most
recent route change(s) including the RIB and FIB, along with
software and hardware tables. Route Convergence can be observed
externally by the rerouting of data traffic.
Measurement Units:
Converged or Not Converged
Issues:
None
See Also:
Route Convergence Time
Network Convergence
Protocol Convergence
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3.4 Full Route Convergence Time
Definition:
The amount of time it takes for Route Convergence to
complete as measured by the time to drop from maximum
forwarding rate and return to maximum forwarding rate
after occurrence of a network event.
Discussion:
Full Route Convergence Time is a metric applied
to a single router. Convergence Time could be calculated
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
from the data plane. IGP Route Convergence Time is the
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).
Forwarding Rate versus Time
Time=Recovery Time=Network Event Time = 0sec
Maximum ^ ^ ^
Forwarding Rate--> ----\ /-----------
\ /<----Route Convergence
Route Convergence------->\ / Event Slope
Recovery Slope \_______/<------100% Packet Loss
X-axis = Time
Y-axis = Forwarding Rate
Figure 1. Convergence Graph
Measurement Units:
seconds/milliseconds
Issues:
None
See Also:
Route Convergence
Route Convergence Packet Loss
Average Route Convergence Time
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3.5 Route Convergence Packet Loss
Definition:
The amount of packet loss until Route Convergence completes.
Discussion:
Route Convergence Packet Loss is used to calculate the
Route Convergence Time. Packet loss is an externally
measurable metric.
Measurement Units:
number of packets
Issues:
None
See Also:
Route Convergence
Full Route Convergence Time
Route Convergence Event Slope
Route Convergence Recovery Slope
3.6 Average Route Convergence Time
Definition:
The amount of time it takes for Route Convergence to
complete as calculated from the amount of packet loss
and known forwarding rate.
Discussion:
Average Route Convergence Time is a metric applied to a
single router. It can be calculated from packet loss that
occurs due to a network event and subsequent Route
Convergence.
Measurement Units:
seconds/milliseconds
Issues:
Use of Packet loss to calculate Route Convergence Time will
give a better than actual result when converging many routes
simultaneously. Full Route Convergence Time is
the preferred benchmark for IGP Route Convergence.
See Also:
Route Convergence
Route Convergence Packet Loss
Full Route Convergence Time
Route Convergence Event Slope
Route Convergence Recovery Slope
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3.7 Route Convergence Event Slope
Definition:
The characteristic of routers in which forwarding rate
gradually reaches zero as output queues drain after a
network event.
Discussion:
Route Convergence Event Slope is externally observable.
Full Route Convergence Time ignores the Route
Convergence Event Slope. Average Route Convergence
Time based upon the amount of packet loss takes the
Route Convergence Event Slope into account.
Measurement Units:
seconds/milliseconds
Issues:
None
See Also:
Route Convergence
Full Route Convergence Time
Average Route Convergence Time
Route Convergence Packet Loss
Route Convergence Recovery Slope
3.8 Route Convergence Recovery Slope
Definition:
The characteristic of routers in which forwarding rate
gradually rises to the maximum value as many routes
converge to recover from a network event.
Discussion:
Route Convergence Recovery Slope is externally observable.
Full Route Convergence Time ignores the Route
Convergence Recovery Slope. Average Route Convergence
Time based upon the amount of packet loss takes the
Route Convergence Recovery Slope into account.
Measurement Units:
seconds/milliseconds
Issues:
None
See Also:
Route Convergence
Full Route Convergence Time
Average Route Convergence Time
Route Convergence Packet Loss
Route Convergence Event Slope
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3.9 Reroute Convergence Time
Definition:
The amount of time it takes for Route Convergence to
complete as observed from rerouting of traffic to a
new egress interface.
Discussion:
Reroute Convergence Time is the IGP Route Convergence
benchmark to be used for network events that produce
a change in next-hop without packet loss. An example
of this is a cost change in which an backup path becomes
the preferred path.
Measurement Units:
seconds/milliseconds
Issues:
None
See Also:
Route Convergence
Full Route Convergence Time
Average Route Convergence Time
3.10 Local Interface
Definition:
An interface on the DUT.
Discussion:
None
Measurement Units:
N/A
Issues:
None
See Also:
Neighbor Interface
Remote interface
3.11 Neighbor Interface
Definition:
The interface on the neighbor router or tester that is
directly linked to the DUT's Local Interface.
Discussion:
None
Measurement Units:
N/A
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Issues:
None
See Also:
Local Interface
Remote interface
3.12 Remote Interface
Definition:
An interface on a neighboring router that is not directly
linked to any interface on the DUT.
Discussion:
None
Measurement Units:
N/A
Issues:
None
See Also:
Local interface
Neighbor Interface
4. Security Considerations
Documents of this type do not directly effect the security of
the Internet or of corporate networks as long as benchmarking
is not performed on devices or systems connected to operating
networks.
5. References
[1] Poretsky, S., "Benchmarking Applicability for IGP Data Plane
Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-app-00,
work in progress, June 2003.
[2] Poretsky, S., "Benchmarking Terminology for IGP Data Plane
Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-term-00,
work in progress, June 2003.
[3] Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual
Environments", RFC 1195, December 1990.
[4] Moy, J., "OSPF Version 2", RFC 2328, IETF, April 1998.
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6. Author's Address
Scott Poretsky
Avici Systems
101 Billerica Avenue
N. Billerica, MA 01862
USA
Phone: + 1 978 964 2287
EMail: sporetsky@avici.com
7. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights
Reserved.
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furnished to others, and derivative works that comment on or
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not be modified in any way, such as by removing the copyright
notice or references to the Internet Society or other Internet
organizations, except as needed for the purpose of developing
Internet standards in which case the procedures for copyrights
defined in the Internet Standards process must be followed, or
as required to translate it into languages other than English.
The limited permissions granted above are perpetual and will
not be revoked by the Internet Society or its successors or
assigns. This document and the information contained herein is
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FOR A PARTICULAR PURPOSE.
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