Network Working Group INTERNET-DRAFT Expires in: October 2005 Scott Poretsky Quarry Technologies Brent Imhoff LightCore February 2005 Terminology for Benchmarking IGP Data Plane Route Convergence <draft-ietf-bmwg-igp-dataplane-conv-term-05.txt> Intellectual Property Rights (IPR) statement: By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, or will be disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. ABSTRACT This draft describes the terminology for benchmarking IGP Route Convergence as described in Applicability document [1] and Methodology document [2]. The methodology and terminology is to be used for benchmarking Route Convergence and 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 described in [2]. Poretsky, Imhoff [Page 1]

INTERNET-DRAFT Benchmarking Terminology for February 2005 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. Security Considerations.......................................13 5. Normative References..........................................14 6. Author's Address..............................................14 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 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 [2]. These terms apply to IPv4 and IPv6 traffic as well as IPv4 and IPv6 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 components of the graph and metrics are defined in the Term Definitions section. Poretsky, Imhoff [Page 2]

INTERNET-DRAFT Benchmarking Terminology for February 2005 IGP Data Plane Route Convergence Convergence Convergence Recovery Event Instant Instant Time = 0sec Maximum ^ ^ ^ Forwarding Rate--> ----\ Packet /--------------- \ Loss /<----Convergence Convergence------->\ / Event Transition Recovery Transition \ / \_____/<------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. 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 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 2005 IGP Data Plane Route Convergence 3.2 Route Convergence Definition: Recovery from a Convergence Event indicated by the DUT forwarding rate 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 RIB and 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 forwarding rate to equal the offered load, no Stale Forwarding, and no blenders[5][6]. Measurement Units: N/A Issues: None See Also: Route Convergence Stale Forwarding Poretsky, Imhoff [Page 4]

INTERNET-DRAFT Benchmarking Terminology for February 2005 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 forwarding rate 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 forwarding rate. Convergence Packet Loss include packets that were lost and packets that were delayed due to buffering. Convergence Packet Loss may or may not reach 100%. Measurement Units: number of packets Issues: None See Also: Route Convergence Convergence Event Rate-Derived Convergence Time Loss-Derived Convergence Time Poretsky, Imhoff [Page 5]

INTERNET-DRAFT Benchmarking Terminology for February 2005 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:uuu 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 2005 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. (eq 1) Rate-Derived Convergence Time = Convergence Recovery Instant - Convergence Event Instant. Discussion: Rate-Derived Convergence Time should be measured at the maximum forwarding rate. 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 forwarding rate 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 2005 IGP Data Plane Route Convergence 3.10 Convergence Recovery Transition Definition: The characteristic of a router in which forwarding rate 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. (eq 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 2005 IGP Data Plane Route Convergence Guidelines for reporting Loss-Derived Convergence Time are provided in [2]. 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 Time benchmarks protected against fluctuation in Forwarding Rate after Full Convergence is observed. The Sustained Forwarding Convergence Time to be used is calculated as shown in Equation 3. (eq 3) Sustained Forwarding Convergence Time = 5 x (# routes in FIB) / (Offered Load) for which at least one packet per destination MUST be received at the DUT. 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 2005 IGP Data Plane Route Convergence 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 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 may 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 as 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 [2]. See Also: Convergence Packet Loss Convergence Event Transition Convergence Recovery Transition Poretsky, Imhoff [Page 10]

INTERNET-DRAFT Benchmarking Terminology for February 2005 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 2005 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: 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: Next-Best Egress Interface is 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 2005 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 occurence of Convergence Event while the route table is converging from a prior Convergence Event. Discussion: The Convergence Events for a Nested Convergence Events 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. 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 operating networks. Poretsky, Imhoff [Page 13]

INTERNET-DRAFT Benchmarking Terminology for February 2005 IGP Data Plane Route Convergence 5. Normative References [1] Poretsky, S., "Benchmarking Applicability for IGP Data Plane Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-app-05, work in progress, February 2005. [2] Poretsky, S., "Benchmarking Methodology for IGP Data Plane Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-meth-05, work in progress, February 2005. [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. [5] S. Casner, C. Alaettinoglu, and C. Kuan, "A Fine-Grained View of High Performance Networking", NANOG 22, May 2001. [6] L. Ciavattone, A. Morton, and G. Ramachandran, "Standardized Active Measurements on a Tier 1 IP Backbone", IEEE Communications Magazine, pp90-97, June, 2003. 6. Author's Address Scott Poretsky Quarry Technologies 8 New England Executive Park Burlington, MA 01803 USA Phone: + 1 781 395 5090 EMail: sporetsky@quarrytech.com Brent Imhoff USA EMail: bimhoff@planetspork.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intel- lectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this docu- ment 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. Poretsky, Imhoff [Page 14]

INTERNET-DRAFT Benchmarking Terminology for February 2005 IGP Data Plane Route Convergence 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 stan- dard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Warranty 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 AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMA- TION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2005). 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. Poretsky, Imhoff [Page 15]