Network Working Group
INTERNET-DRAFT
Expires in: August 2007
Intended Status: Informational
Scott Poretsky
Reef Point Systems
Brent Imhoff
Juniper Networks
February 2007
Terminology for Benchmarking
IGP Data Plane Route Convergence
Intellectual Property Rights (IPR) statement:
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Status of this Memo
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Copyright Notice
Copyright (C) The IETF Trust (2007).
ABSTRACT
This document describes the terminology for benchmarking Interior
Gateway Protocol (IGP) Route Convergence. The terminology is to
be used for benchmarking IGP convergence time through externally
observable (black box) data plane measurements. The terminology
can be applied to any link-state IGP, such as ISIS and OSPF.
Poretsky, Imhoff [Page 1]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
Table of Contents
1. Introduction .................................................2
2. Existing definitions .........................................3
3. Term definitions..............................................3
3.1 Convergence Event.........................................3
3.2 Route Convergence.........................................4
3.3 Network Convergence.......................................4
3.4 Full Convergence..........................................5
3.5 Convergence Packet Loss...................................5
3.6 Convergence Event Instant.................................6
3.7 Convergence Recovery Instant..............................6
3.8 Rate-Derived Convergence Time.............................7
3.9 Convergence Event Transition..............................7
3.10 Convergence Recovery Transition..........................8
3.11 Loss-Derived Convergence Time............................8
3.12 Sustained Forwarding Convergence Time....................9
3.13 Restoration Convergence Time.............................9
3.14 Packet Sampling Interval.................................10
3.15 Local Interface..........................................11
3.16 Neighbor Interface.......................................11
3.17 Remote Interface.........................................11
3.18 Preferred Egress Interface...............................12
3.19 Next-Best Egress Interface...............................12
3.20 Stale Forwarding.........................................13
3.21 Nested Convergence Events................................13
4. IANA Considerations...........................................13
5. Security Considerations.......................................14
6. Acknowledgements..............................................14
7. Normative References..........................................14
8. Author's Address..............................................15
1. Introduction
This draft describes the terminology for benchmarking Interior
Gateway Protocol (IGP) Route Convergence. The motivation and
applicability for this benchmarking is provided in [Po07a]. The
methodology to be used for this benchmarking is described in [Po07m].
The methodology and terminology to be used for benchmarking Route
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
(externally observable) convergence benchmarking metrics. The
purpose of this document is to introduce new terms required to
complete execution of the IGP Route Convergence Methodology [Po07m].
These terms apply to IPv4 and IPv6 traffic and IGPs.
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 Offered Load to the ingress interface of
the DUT SHOULD equal the measured maximum Throughput [Ba99][Ma98]
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
are defined in the Term Definitions section.
Poretsky, Imhoff [Page 2]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
Convergence Convergence
Recovery Event
Instant Instant Time = 0sec
Forwarding Rate = ^ ^ ^ Offered Load =
Offered Load --> ------\ Packet /-------- <---Max Throughput
\ Loss /<----Convergence
Convergence------->\ / Event Transition
Recovery Transition \ /
\_____/<------Maximum Packet Loss
X-axis = Time
Y-axis = Forwarding Rate
Figure 1. Convergence Graph
2. Existing definitions
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 BCP 14, RFC 2119
[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
document uses these keywords, this document is not a standards track
document. The term Throughput is defined in [Ba91] and [Ba99].
3. Term Definitions
3.1 Convergence Event
Definition:
The occurrence of a planned or unplanned action in the network
that results in a change in the egress interface of the Device
Under Test (DUT) for
routed packets.
Discussion:
Convergence Events include link loss, routing protocol session
loss, router failure, configuration change, and better next-hop
learned via a routing protocol.
Measurement Units:
N/A
Issues:
None
See Also:
Convergence Packet Loss
Convergence Event Instant
Poretsky, Imhoff [Page 3]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
3.2 Route Convergence
Definition:
Recovery from a Convergence Event indicated by the DUT
Throughput equal to the offered load.
Discussion:
Route Convergence is the action of all components of the router
being updated with the most recent route change(s) including the
Routing Information Base (RIB) and Forwarding Information Base
(FIB), along with software and hardware tables. Route
Convergence can be observed externally by the rerouting of data
Traffic to a new egress interface.
Measurement Units:
N/A
Issues:
None
See Also:
Network Convergence
Full Convergence
Convergence Event
3.3 Network Convergence
Definition:
The completion of updating of all routing tables, including the
FIB, in all routers throughout the network.
Discussion:
Network Convergence is bounded by the sum of Route Convergence
for all routers in the network. Network Convergence can be
determined by recovery of the Throughput to equal the offered
load, with no Stale Forwarding, and no blenders [Ca01][Ci03].
Measurement Units:
N/A
Issues:
None
See Also:
Route Convergence
Stale Forwarding
Poretsky, Imhoff [Page 4]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
3.4 Full Convergence
Definition:
Route Convergence for an entire FIB.
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. 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.
Measurement Units:
N/A
Issues: None
See Also:
Network Convergence
Route Convergence
Convergence Event
3.5 Convergence Packet Loss
Definition:
The amount of packet loss produced by a Convergence Event
until Route Convergence occurs.
Discussion:
Packet loss can be observed as a reduction of forwarded traffic
from the maximum Throughput. Convergence Packet Loss
includes packets that were lost and packets that were delayed
due to buffering. The maximum Convergence Packet Loss observed
in a Packet Sampling Interval may or may not reach 100% during
Route Convergence (see Figure 1).
Measurement Units:
number of packets
Issues: None
See Also:
Route Convergence
Convergence Event
Rate-Derived Convergence Time
Loss-Derived Convergence Time
Packet Sampling Interval
Poretsky, Imhoff [Page 5]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
3.6 Convergence Event Instant
Definition:
The time instant that a Convergence Event becomes observable in
the data plane.
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:nnn, where 'nnn' is milliseconds
Issues:
None
See Also:
Convergence Event
Convergence Packet Loss
Convergence Recovery Instant
3.7 Convergence Recovery Instant
Definition:
The time instant that Full Convergence is measured
and then maintained for an interval of duration equal to
the Sustained Forwarding Convergence Time
Discussion:
Convergence Recovery Instant is measurable from the data
plane as the precise time that the device under test
achieves Full Convergence.
Measurement Units:
hh:mm:ss:uuu
Issues:
None
See Also:
Sustained Forwarding Convergence Time
Convergence Packet Loss
Convergence Event Instant
Poretsky, Imhoff [Page 6]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
3.8 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.
Rate-Derived Convergence Time can be measured as the time
difference from the Convergence Event Instant to the
Convergence Recovery Instant, as shown with Equation 1.
Equation 1 -
Rate-Derived Convergence Time =
Convergence Recovery Instant - Convergence Event Instant.
Discussion:
Rate-Derived Convergence Time should be measured at the maximum
Throughput. Failure to achieve Full Convergence results in
a Rate-Derived Convergence Time benchmark of infinity.
Measurement Units:
seconds/milliseconds
Issues:
None
See Also:
Convergence Packet Loss
Convergence Recovery Instant
Convergence Event Instant
Full Convergence
3.9 Convergence Event Transition
Definition:
The characteristic of a router in which Throughput
gradually reduces to zero after a Convergence Event.
Discussion:
The Convergence Event Transition is best observed for
Full Convergence. The Convergence Event Transition may
not be linear.
Measurement Units:
seconds/milliseconds
Issues:
None
See Also:
Convergence Event
Rate-Derived Convergence Time
Convergence Packet Loss
Convergence Recovery Transition
Poretsky, Imhoff [Page 7]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
3.10 Convergence Recovery Transition
Definition:
The characteristic of a router in which Throughput
gradually increases to equal the offered load.
Discussion:
The Convergence Recovery Transition is best observed for
Full Convergence. The Convergence Event Transition may
not be linear.
Measurement Units:
seconds/milliseconds
Issues: None
See Also:
Full Convergence
Rate-Derived Convergence Time
Convergence Packet Loss
Convergence Event Transition
3.11 Loss-Derived Convergence Time
Definition:
The amount of time it takes for Route Convergence to
to be achieved as calculated from the Convergence Packet
Loss. Loss-Derived Convergence Time can be calculated
from Convergence Packet Loss that occurs due to a
Convergence Event and Route Convergence as shown with
Equation 2.
Equation 2 -
Loss-Derived Convergence Time =
Convergence Packets Loss / Offered Load
NOTE: Units for this measurement are
packets / packets/second = seconds
Discussion:
Loss-Derived Convergence Time gives a better than
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
Rate-Derived Convergence Time = Loss-Derived Convergence Time.
However, router implementations are less than ideal.
For these reasons the preferred reporting benchmark for IGP
Route Convergence is the Rate-Derived Convergence Time.
Poretsky, Imhoff [Page 8]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
Guidelines for reporting Loss-Derived Convergence Time are
provided in [Po07m].
Measurement Units:
seconds/milliseconds
Issues:
None
See Also:
Route Convergence
Convergence Packet Loss
Rate-Derived Convergence Time
Convergence Event Transition
Convergence Recovery Transition
3.12 Sustained Forwarding Convergence Time
Definition:
The amount of time for which Full Convergence is maintained
without additional packet loss.
Discussion:
The purpose of the Sustained Forwarding Convergence Time is to
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 -
Sustained Forwarding Convergence Time =
5*(Convergence Packet Loss/Offered Load)
units are packets/pps = sec
for which at least one packet per route in the FIB for all
routes in the FIB MUST be offered to the DUT per second.
Measurement Units:
seconds or milliseconds
Issues: None
See Also:
Full Convergence
Convergence Recovery Instant
3.13 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.
Poretsky, Imhoff [Page 9]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
Discussion:
Restoration Convergence Time is the amount of time for routes
to converge 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 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 Convergence Time
3.14 Packet Sampling Interval
Definition:
The interval at which the tester (test equipment) polls to make
measurements for arriving packet flows.
Discussion:
Metrics measured at the Packet Sampling Interval MUST include
Forwarding Rate and Convergence Packet Loss.
Measurement Units:
seconds or milliseconds
Issues:
Packet Sampling Interval can influence the Convergence Graph.
This is particularly true when implementations achieve Full
Convergence in less than 1 second. 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. The recommended value for configuration
of the Packet Sampling Interval is provided in [Po07m].
See Also:
Convergence Packet Loss
Convergence Event Transition
Convergence Recovery Transition
Poretsky, Imhoff [Page 10]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
3.15 Local Interface
Definition:
An interface on the DUT.
Discussion:
None
Measurement Units:
N/A
Issues:
None
See Also:
Neighbor Interface
Remote Interface
3.16 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
Issues:
None
See Also:
Local Interface
Remote Interface
3.17 Remote Interface
Definition:
An interface on a neighboring router that is not directly
connected to any interface on the DUT.
Discussion:
None
Measurement Units:
N/A
Issues:
None
Poretsky, Imhoff [Page 11]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
See Also:
Local Interface
Neighbor Interface
3.18 Preferred Egress Interface
Definition:
The outbound interface from the DUT for traffic routed to the
preferred next-hop.
Discussion:
The Preferred Egress Interface is the egress interface prior
to a Convergence Event.
Measurement Units:
N/A
Issues:
None
See Also:
Next-Best Egress Interface
3.19 Next-Best Egress Interface
Definition:
The outbound interface from the DUT for traffic routed to the
second-best next-hop. It is the same media type and link speed
as the Preferred Egress Interface
Discussion:
The Next-Best Egress Interface becomes the egress interface
after a Convergence Event.
Measurement Units:
N/A
Issues:
None
See Also:
Preferred Egress Interface
Poretsky, Imhoff [Page 12]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
3.20 Stale Forwarding
Definition:
Forwarding of traffic to route entries that no longer exist
or to route entries with next-hops that are no longer preferred.
Discussion:
Stale Forwarding can be caused by a Convergence Event and is
also known as a "black-hole" since it may produce packet loss.
Stale Forwarding exists until Network Convergence is achieved.
Measurement Units:
N/A
Issues:
None
See Also:
Network Convergence
3.21 Nested Convergence Events
Definition:
The occurrence of a Convergence Event while the route
table is converging from a prior Convergence Event.
Discussion:
The Convergence Events for a Nested Convergence Event
MUST occur with different neighbors. A common
observation from a Nested Convergence Event will be
the withdrawal of routes from one neighbor while the
routes of another neighbor are being installed.
Measurement Units:
N/A
Issues:
None
See Also:
Convergence Event
4. IANA Considerations
This document requires no IANA considerations.
Poretsky, Imhoff [Page 13]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
5. Security Considerations
Documents of this type do not directly affect the security of
Internet or corporate networks as long as benchmarking
is not performed on devices or systems connected to production
networks.
6. Acknowledgements
Thanks to Sue Hares, Al Morton, Kevin Dubray, and participants of
the BMWG for their contributions to this work.
7. References
7.1 Normative References
[Ba91] Bradner, S. "Benchmarking Terminology for Network
Interconnection Devices", RFC1242, July 1991.
[Ba99] Bradner, S. and McQuaid, J., "Benchmarking
Methodology for Network Interconnect Devices",
RFC 2544, March 1999.
[Br97] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997
[Ca90] Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual
Environments", RFC 1195, December 1990.
[Ma98] Mandeville, R., "Benchmarking Terminology for LAN
Switching Devices", RFC 2285, February 1998.
[Mo98] Moy, J., "OSPF Version 2", RFC 2328, IETF, April 1998.
[Po07a] Poretsky, S., "Benchmarking Applicability for IGP Data Plane
Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-app-12,
work in progress, February 2007.
[Po07m] Poretsky, S., "Benchmarking Methodology for IGP Data Plane
Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-meth-12,
work in progress, February 2007.
7.2 Informative References
[Ca01] S. Casner, C. Alaettinoglu, and C. Kuan, "A Fine-Grained View
of High Performance Networking", NANOG 22, June 2001.
[Ci03] L. Ciavattone, A. Morton, and G. Ramachandran, "Standardized
Active Measurements on a Tier 1 IP Backbone", IEEE
Communications Magazine, pp90-97, May 2003.
Poretsky, Imhoff [Page 14]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
8. Author's Address
Scott Poretsky
Reef Point Systems
8 New England Executive Park
Burlington, MA 01803
USA
Phone: + 1 508 439 9008
EMail: sporetsky@reefpoint.com
Brent Imhoff
Juniper Networks
1194 North Mathilda Ave
Sunnyvale, CA 94089
USA
Phone: + 1 314 378 2571
EMail: bimhoff@planetspork.com
Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided
on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE.
Poretsky, Imhoff [Page 15]
INTERNET-DRAFT Benchmarking Terminology for February 2007
IGP Data Plane Route Convergence
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Poretsky, Imhoff [Page 16]