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   Network Working Group
   INTERNET-DRAFT
   Expires in: December 2003
                                                   Scott Poretsky
                                                   Avici Systems

                                                   June 2003

                        Terminology for Benchmarking
                      IGP Data Plane Route Convergence

                <draft-ietf-bmwg-igp-dataplane-conv-term-00.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............................................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

Poretsky                                                        [Page 1]


INTERNET-DRAFT          Benchmarking Terminology for            June 2003
                                    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





Poretsky                                                        [Page 2]


INTERNET-DRAFT          Benchmarking Terminology for            June 2003
                      IGP Data Plane 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:
        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





Poretsky                                                        [Page 3]


INTERNET-DRAFT          Benchmarking Terminology for            June 2003
                      IGP Data Plane Route Convergence

   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

Poretsky                                                        [Page 4]


INTERNET-DRAFT          Benchmarking Terminology for            June 2003
                      IGP Data Plane Route Convergence

   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


Poretsky                                                        [Page 5]


INTERNET-DRAFT          Benchmarking Terminology for            June 2003
                      IGP Data Plane Route Convergence

  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
Poretsky                                                        [Page 6]


INTERNET-DRAFT          Benchmarking Terminology for            June 2003
                      IGP Data Plane Route Convergence

   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
Poretsky                                                        [Page 7]


INTERNET-DRAFT          Benchmarking Terminology for            June 2003
                      IGP Data Plane Route Convergence


        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.




Poretsky                                                        [Page 8]


INTERNET-DRAFT          Benchmarking Terminology for            June 2003
                      IGP Data Plane Route Convergence

  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.

        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                                                        [Page 9]


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