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   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
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        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]


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   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]


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   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]


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                      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]


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                      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]


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        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
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        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]


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                      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]


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   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
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   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
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        FOR A PARTICULAR PURPOSE.

















Poretsky, Imhoff                                                                [Page 13]


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