Network Working Group INTERNET-DRAFT Expires in: April 2004 Scott Poretsky Quarry Technologies Brent Imhoff Wiltel Communications October 2003 Terminology for Benchmarking IGP Data Plane Route Convergence <draft-ietf-bmwg-igp-dataplane-conv-term-01.txt> 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. Table of Contents 1. Introduction ...............................................2 2. Existing definitions .......................................2 3. Term definitions............................................3 3.1 Network Convergence.......................................3 3.2 Protocol Convergence......................................3 3.3 Route Convergence.........................................4 3.4 Convergence Event.........................................4 3.5 Full Convergence..........................................4 3.6 Convergence Packet Loss...................................5 3.7 Convergence Event Instant.................................5 3.8 Convergence Recovery Transition...........................6 3.9 Rate-Derived Convergence Time.............................6 3.10 Convergence Recovery Instant.............................7 3.11 Convergence Event Transition.............................7 3.12 Loss-Derived Convergence Time............................8 Poretsky, Imhoff [Page 1]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence 3.13 Route Convergence Time...................................9 3.14 Restoration Convergence Time.............................9 3.15 Packet Sampling Interval.................................10 3.16 Local Interface..........................................10 3.17 Neighbor Interface.......................................10 3.18 Remote Interface.........................................11 3.19 Preferred Egress Interface...............................11 3.20 Next-Best Egress Interface...............................12 4. Security Considerations.....................................12 5. References..................................................12 6. Author's Address............................................12 7. Full Copyright Statement....................................13 1. Introduction 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]. An example of Route Convergence as observed and measured from the data plane is shown in Figure 1. The graph in Figure 1 shows Forwarding Rate versus Time. Time 0 on the X-axis is on the far right of the graph. The components of the graph and metrics are defined in the Term Definitions section of this document. Recovery Convergence Event Time = 0sec Maximum ^ ^ ^ Forwarding Rate--> ----\ Packet /--------------- \ Loss /<----Convergence Convergence------->\ / Event Transition Recovery Transition \ / \_____/<------100% Packet Loss X-axis = Time Y-axis = Forwarding Rate Figure 1. Convergence Graph 2. Existing definitions For the sake of clarity and continuity this RFC adopts the template for 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. Poretsky, Imhoff [Page 2]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence 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: N/A Issues: None See Also: Protocol Convergence Route Convergence 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: N/A Issues: Protocol Convergence does not consider updating of the FIB, hardware updating, rerouting of traffic, and resulting packet loss. Protocol Convergence is only a partial measurement of Route Convergence. See Also: Network Convergence Route Convergence Poretsky, Imhoff [Page 3]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence 3.3 Route Convergence Definition: The completion of the router's FIB becoming fully converged. 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 Protocol Convergence Full Convergence Convergence Event 3.4 Convergence Event Definition: The occurrence of a planned or unplanned action in the network that results in a change to an entry in the route table. Discussion: Convergence Events include link loss, routing protocol session loss, router failure, and better next-hop. Measurement Units: N/A Issues: None See Also: Convergence Packet Loss Convergence Event Instant 3.5 Full Convergence Definition: Route Convergence for an entire route table. Discussion: When benchmarking convergence it is useful to measure The time to convergence an entire route table. For example, Poretsky, Imhoff [Page 4]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence A Convergence Event can produced for an OSPF table of 5000 routes so that the time to converge routes 1 through 5000 is measured. Measurement Units: N/A Issues: None See Also: Network Convergence Protocol Convergence Route Convergence Convergence Event 3.6 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. Measurement Units: number of packets Issues: None See Also: Route Convergence Convergence Event Rate-Derived Convergence Time Loss-Derived Convergence Time 3.7 Convergence Event Instant Definition: The time instant that a Convergence Event occurs. Discussion: Convergence Event Instant is observable from the data plane as the precise time that the device under test begins to exhibit packet loss. Measurement Units: hh:mm:ss:uuu Poretsky, Imhoff [Page 5]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence Issues: None See Also: Route Convergence Convergence Event Convergence Packet Loss Convergence Recovery Instant 3.8 Convergence Recovery Instant Definition: The time instant that Route Convergence occurs. Discussion: Convergence Recovery Instant is observable from the data plane as the precise time that the device under test no longer exhibits packet loss. Measurement Units: hh:mm:ss:uuu Issues: None See Also: Route Convergence Convergence Packet Loss Convergence Event Instant 3.9 Rate-Derived Convergence Time Definition: The amount of time for Convergence Packet Loss to persist upon occurrence of a Convergence Event until occurrence of Route Convergence. Discussion: Rate-Derived Convergence Time can be measured as the time difference from the Convergence Event Instant to the Convergence Reovery Instant, as shown with Equation 1. (eq 1) Rate-Derived Convergence Time = Convergence Recovery Instant - Convergence Event Instant. Rate-Derived Convergence Time can be measured at the maximum forwarding rate. Measurement Units: seconds/milliseconds Poretsky, Imhoff [Page 6]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence Issues: None See Also: Route Convergence Convergence Packet Loss Loss-Derived Convergence Time 3.10 Loss-Derived Convergence Time Definition: The amount of time it takes for Route Convergence to complete as calculated from the amount of packet loss and known forwarding rate. Discussion: It can be calculated from 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 / Forwarding Rate NOTE: Units for this measurement are packets / packets/second = seconds Measurement Units: seconds/milliseconds Issues: Loss-Derived Convergence time gives a better than actual result when converging many routes simultaneously. Because of this the preferred reporting metric in most Cases is Rate-Derived Convergence Time. See Also: Route Convergence Convergence Packet Loss Rate-Derived Convergence Time Convergence Event Transition Convergence Recovery Transition 3.11 Convergence Event Transition Definition: The characteristic of A router in which forwarding rate gradually reaches zero as output queues drain after a network event. Poretsky, Imhoff [Page 7]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence Discussion: Rate-Derived Convergence Time ignores the Convergence Event Transition. Loss-Derived Convergence Time based upon the amount of packet loss takes the Convergence Event Transition into account. The Convergence Event Transition is best observed for Full Convergence. Measurement Units: seconds/milliseconds Issues: None See Also: Route Convergence Convergence Event Rate-Derived Convergence Time Loss-Derived Convergence Time Convergence Packet Loss Convergence Recovery Transition 3.12 Convergence Recovery Transition Definition: The characteristic of a router in which forwarding rate gradually rises to the maximum value as many routes converge to recover from a network event. Discussion: Rate-Derived Convergence Time ignores the Route Convergence Recovery Transition. Loss-Derived Convergence Time based upon the amount of packet loss takes the Convergence Recovery Transition into account. The Convergence Recovery Transition is best observed for Full Convergence. Measurement Units: seconds/milliseconds Issues: None See Also: Route Convergence Rate-Derived Convergence Time Loss-Derived Convergence Time Convergence Packet Loss Convergence Event Transition Poretsky, Imhoff [Page 8]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence 3.13 Route Convergence Time Definition: The amount of time it takes for Route Convergence to complete as observed from rerouting traffic to a new egress interface due to a change in next-hop without packet loss. Discussion: Route Convergence Time is the IGP Route Convergence benchmark to be used for network events that produce a change in next-hop without packet loss. Measurement Units: seconds/milliseconds Issues: None See Also: Route Convergence Rate-Derived Convergence Time Loss-Derived Convergence Time 3.14 Restoration Convergence Time Definition: The amount of time for the router under test to restore traffic to the original outbound port after recovery from a Convergence Event. Discussion: Restoration Convergence Time is the amount of time to Converge back to the original outbound port. This is achieved by recovering from the Convergence Event, such as restoring the failed link. Restoration Convergence Time is measured using the Rate-Derived Convergence Time calculation technique, as provided in Equation 1. It is possible, but not desired to have the Restoration Convergence Time differ from the Rate-Derived Convergence Time. Measurement Units: seconds or milliseconds Issues: None See Also: Convergence Event Rate-Derived Convegence Time Poretsky, Imhoff [Page 9]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence 3.15 Packet Sampling Interval Definition: The rate at which the tester (test equipment) polls to make measurements for arriving packet flows. Discussion: Metrics measured at the Packet Sampling Interval include packets received and Convergence Packet Loss. Measurement Units: seconds or milliseconds Issues: Packet Sampling Interval can influence the Convergence Graph. This is particularly true as Full Convergence less than 1 second is achieved. The Convergence Event Transition and Convergence Recovery Transition can become exaggerated when the Packet Sampling Interval is too long. This will produce a larger than actual Rate-Derived Convergence Time. Guidelines for use of the Packet Sampling Interval are provided in [2]. See Also: Convergence Packet Loss Convergence Event Transition Convergence Recovery Transition 3.16 Local Interface Definition: An interface on the DUT. Discussion: None Measurement Units: N/A Issues: None See Also: Neighbor Interface Remote interface 3.17 Neighbor Interface Definition: The interface on the neighbor router or tester that is directly linked to the DUT's Local Interface. Discussion: None Poretsky, Imhoff [Page 10]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence Measurement Units: N/A Issues: None See Also: Local Interface Remote interface 3.18 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 3.19 Preferred Egress Interface Definition: The outbound interface on DUT to the preferred next-hop. Discussion: Preferred Egress Interface is the egress interface prior to a Convergence Event Measurement Units: N/A Issues: None See Also: Next-Best Egress Interface Convergence Event Poretsky, Imhoff [Page 11]

INTERNET-DRAFT Benchmarking Terminology for October 2003 IGP Data Plane Route Convergence 3.20 Next-Best Egress Interface Definition: The outbound interface on DUT to the second-best next-hop. Discussion: Next-Best Egress Interface is the egress interface after to a Convergence Event Measurement Units: N/A Issues: None See Also: Preferred Egress Interface Convergence Event 4. Security Considerations 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-01, work in progress, October 2003. [2] Poretsky, S., "Benchmarking Methodology for IGP Data Plane Route Convergence", draft-ietf-bmwg-igp-dataplane-conv-meth-01, work in progress, October 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. 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 Poretsky, Imhoff [Page 12]

```
INTERNET-DRAFT Benchmarking Terminology for October 2003
IGP Data Plane Route Convergence
Brent Imhoff
WilTel Communications
3180 Rider Trail South
Bridgeton, MO 63045 USA
Phone: +1 314 595 6853
EMail: brent.imhoff@wcg.com
7. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights
Reserved.
This document and translations of it may be copied and
furnished to others, and derivative works that comment on or
otherwise explain it or assist in its implementation may be
prepared, copied, published and distributed, in whole or in
part, without restriction of any kind, provided that the above
copyright notice and this paragraph are included on all such
copies and derivative works. However, this document itself may
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
provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE
INTERNET ENGINEERING TASK FORCE DISCLAIMS 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 13]
```