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Network Working Group                                     Vishwas Manral
Internet Draft                                          Netplane Systems
                                                              Russ White
                                                           Cisco Systems
                                                             Aman Shaikh
Expiration Date: October 2002                   University of California
File Name: draft-bmwg-ospfconv-intraarea-00.txt                 May 2002

          Benchmarking Methodology for Basic OSPF Convergence
                 draft-bmwg-ospfconv-intraarea-00.txt


1. 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.  Internet Drafts may be updated, replaced, or obsoleted by
   other documents at any time. It is not appropriate to use Internet
   Drafts as reference material or to cite them other than as a "working
   draft" or "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.


2. Abstract

   This draft establishes standards for measuring OSPF convergence
   performance on a single router (SR-Convergence [4]). Its initial
   emphasis is on the control plane of single OSPF routers.  We do not
   address forwarding plane performance.











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3. Conventions used in this document

   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 [1].


4. Motivation

   There is a growing interest in routing protocol SR-Convergence
   testing, with many people looking at various tests to determine how
   long it takes for a network to converge after various conditions
   occur. The major problem with this sort of testing is that the
   framework of the tests has a major impact on the results; for
   instance, determining when a network is converged, what parts of the
   router's operation are considered within the testing, and other such
   things will have a major impact on what apparent performance routing
   protocols provide.

   This document attempts to provide a framework within which Open
   Shortest Path First (OSPF) [2] performance testing can be placed, and
   provide some tests with which some aspects of OSPF performance can be
   measured. The motivation of the draft is to provide a set of tests
   that can provide the user comparable data from various vendors with
   which to evaluate the OSPF protocol performance on the devices.


5. Overview & Scope

   While this document describes a specific set of tests aimed at
   characterizing the SR-Convergence performance of OSPF processes in
   routers or other boxes that incorporate OSPF functionality, a key
   objective is to propose methodology that will standardize the
   conducting and reporting of convergence-related measurements.

   Things which are outside the scope of this document include:


      o    The interactions of SR-Convergence and forwarding; testing is
           restricted to events occurring within the control plane. For-
           warding performance is the primary focus in [3] and it is
           expected to be dealt with in work that ensues from [6].

      o    Inter area routing, AS-external routing, and simultaneous
           traffic on the control and data paths within the DUT.

   Other drafts in the future may cover some of the items noted as not
   covered in the scope of this draft. For a discussion of the



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   terminology used in this draft (in relation to the tests themselves),
   refer to [4].


6. Test Conditions

   In all tests, the following test conditions will be assumed:


      o    The link speed should be high enough so that does not become
           a bottleneck. Link speeds of 10MBps or higher are recom-
           mended. The link speed between routers should be specified in
           the test report.

      o    For all point-to-point links, it is assumed that a link
           failure results in an immediate notification to the operating
           system, and thus to the OSPF process; this is explained
           thoroughly in [5].

      o    No data traffic will be running between the routers during
           these tests.

      o    Optional capabilities which can reduce performance, such as
           authentication, should be noted in the test results if they
           are enabled.

      o    Optional changes in the default timer values, such as the
           SPF, hello, router dead, and other intervals, should be noted
           in the test results.

      o    All places where injecting a set of LSAs is referenced, the
           set can include varying numbers of LSAs of varying types
           representing a varying number of reachable destinations. See
           [4] for further information about issues with LSA sets and
           network topologies.

           Tests should be run more than once, since a single test run
           cannot be relied on to produce statistically sound results.
           The number of test runs and any variations between the tests
           should be recorded in the test results (see [4] for more
           information on what items should be recorded in the test
           results).









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7. Reference Topologies

   Several reference topologies will be used throughout the tests
   described in the remainder of this document. Rather than repeating
   these topologies, we've gathered them all in one section.


      o    Reference Topology 1

                                (                   )
           DUT----Generator----(  emulated topology  )
                                (                   )

           A simple back-to-back configuration. It's assumed that the
           link between the generator and the DUT is a point-to-point
           link, while the connections within the generator represent
           some emulated topology.

      o    Reference Topology 2

                                             (                   )
           Collector-----DUT-----Generator--(  emulated topology  )
                  \              /          (                   )
                   \------------/

           All routers are connected through point-to-point links. The
           cost of all links is assumed to be the same unless otherwise
           noted.

      o    Reference Topology 3

           DUT     R1     R2
            |      |      |
           -+------+------+-----.....

           Any number of routers could be included on the common broad-
           cast network.

      o    Reference Topology 4

             /--(link 1)-----\           (                   )
           DUT               Generator--(  emulated topology  )
             \--(link 2)-----/           (                   )

   In all cases the tests and topologies are designed to allow perfor-
   mance measurements to be taken all on a single device, whether the
   DUT or some other device in the network. This eliminates the need for
   syncronized clocks within the test networks.



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8. Basic Process Performance Tests

   These tests will measure aspects of the OSPF implementation as a pro-
   cess on the device under test, including:


 o    Time required to process an LSA

 o    Flooding time

 o    Shortest Path First computation


8.1. Time required to process an LSA


      o    Using reference topology 1, begin with all links up and a
           full adjacency established between the DUT and the generator.

      o    Send an LSA that is already there in the DUT (a duplicate
           LSA), note the time difference between when the LSA is sent
           to when the ack is received. This measures the time to pro-
           pagate the LSA and the ack, as well as processing time of the
           duplicate LSA. This is dupLSAprocTime.

      o    Send a new LSA from the generator to the DUT, followed
           immediately by a duplicate LSA (LSA that already resides in
           the database of DUT, but not the same as the one just sent).

      o    The DUT will acknowledge this second LSA immediately; note
           the time of this acknowledgement. This is newLSAprocTime.

           The amount of time required for an OSPF implementation to
           process the new LSA can be computed by subtracting
           dupLSAprocTime from newLSAprocTime.

           Note: The duplicate LSA cannot be the same as the one just
           sent because of the MinLSInterval restriction.[RFC2328] This
           test is taken from [7].


8.2. Flooding Time


         o    Using reference topology 2, enable OSPF on all links and
              allow the devices to build full adjacencies. Configure the
              collector so it will block all flooding towards the DUT,
              although it continues receiving advertisements from the



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              DUT.

         o    Inject a new set of LSAs from the generator towards the
              collector and the DUT.

         o    On the collector, note the time the flooding is complete
              across the link to the generator. Also note the time the
              flooding is complete across the link from the DUT.

           Two measurements can be taken from this test:



         o    The time between the last LSA is received on the collec-
              tor from the generator and the time the last LSA is
              received on the collector from the DUT.

         o    The time between the last LSA is received on the collector
              from the generator and the time the first LSA is received
              on the collector from the DUT.

           Depending on the number of LSAs flooded, the sizes of the
           LSAs, and the rate of flooding, these numbers could vary by
           some amount. The settings and variances of these numbers
           should be reported with the test results.

           This time is important in link state protocols, since the
           loop free nature of the network is reliant on the speed at
           which revised topology information is flooded.


8.3. Shortest Path First Computation Time (Internal Test)


         o    Using reference topology 1, establish a full adjacency
              between the generator and the DUT.

         o    Inject a set of LSAs from the generator towards the DUT.
              Allow the DUT to stabilize and install all best paths in
              the routing table, etc.

         o    Change the link cost between the DUT and the generator (or
              the link between the generator and the emulated network it
              is advertising), such that a full SPF is required to run,
              although only one piece of information is changed.

         o    Measure the amount of time required for the DUT to compute
              new shortest path tree as a result of the topology changes



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              injected by the generator. These measurements should be
              taken using available show and debug information on the
              DUT.

           The test results should note what available commands were
           used to determine the length of the shortest path first run,
           and should note any performance implications of monitoring
           the SPF calculations using information available from the DUT
           itself.


8.4. Shortest Path First Computation Time (External Test)


         o    Use reference topology 1, beginning with the DUT and the
              generator fully adjacent.

         o    The default SPF timer on the DUT should be set to 0, so
              that any new LSA that arrives, immediately results in the
              SPF calculation [7].

         o    The generator should inject a set of LSAs towards the DUT;
              the DUT should be allowed to converge and install all best
              paths in the local routing table, etc..

         o    Send an LSA that is already there in the DUT (a duplicate
              LSA), note the time difference between when the LSA is
              sent to when the ack is received. This measures the time
              to propagate the LSA and the ack, as well as processing
              time of the duplicate LSA. This is dupLSAprocTime.

         o    Change the link cost between the generator and the emu-
              lated network it is advertising.

         o    Immediately inject another LSA which is a duplicate of
              some other LSA the generator has previously injected
              (preferrably a stub network someplace within the emulated
              network).

         o    Measure the time between transmitting the second (dupli-
              cate) LSA and the acknowledgement for that LSA; this is
              the totalSPFtime. The total time required to run SPF can
              be computed by subtracting dupLSAprocTime from totalSPF-
              time.

           The accuracy of this test is crucially dependant on the
           amount of time between the transmission of the first and
           second LSAs. If there is too much time between them, the test



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           is meaningless because the SPF run will complete before the
           second (duplicate) LSA is received. If there is too little
           time between the LSAs being generated, then they will both be
           handled before the SPF run is scheduled and started, and thus
           the measurement would only be for the handling of the dupli-
           cate LSA.

           This test is also specified in [7].

           Note: This test may not be accurate on systems which imple-
           ment OSPF as a multithreaded process, where the flooding
           takes place in a separate process (or on a different proces-
           sor) than shortest path first computations.


9. Basic Intra-Area OSPF tests

   These tests measure the performance of an OSPF implementation for
   basic intra-area tasks, including:


 o    Forming Adjacencies on Point-to-Point Link Initialization

 o    Forming Adjacencies on Point-to-Point Links

 o    Link Up with Information Already in the Database

 o    Initial SR-Convergence Time on a DR electing (broadcast) network

 o    Point-to-point Link Down with Layer 2 Detection

 o    Broadcast Media Link Down with Layer 3 Detection

 o    Designated Router Election Time on A Broadcast Network


9.1. Forming Adjacencies on Point-to-Point Link Initialization


         o    Use reference topology 1, beginning with the link between
              the generator and DUT disabled on the DUT. OSPF should be
              configured and operating on both devices.

         o    Inject a set of LSAs from the generator towards the DUT.

         o    Bring the link up at the DUT, noting the time that the
              link carrier is established on the generator.




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         o    Note the time the acknowledgement for the last LSA
              transmitted from the DUT is received on the generator.

           The time between the carrier establishment and the ack-
           nowledgement for the last LSA transmitted by the generator
           should be taken as the total amount of time required for the
           OSPF process on the DUT to react to a link up event with the
           set of LSAs injected, including the time required for the
           operating system to notify the OSPF process about the link
           up, etc.. The acknowledgement for the last LSA transmitted is
           used instead of the last acknowledgement received in order to
           prevent timing skews due to retransmitted acknowledgements or
           LSAs.


9.2. Forming Adjacencies on Point-to-Point Links


         o    Using reference topology 1, configure the DUT and the gen-
              erator so traffic can be passed along the link between
              them.

         o    Configure the generator so OSPF is running on the point-
              to-point link towards the DUT, and inject a set of LSAs.

         o    Configure the DUT so OSPF is initialized, but not running
              on the point-to-point link between the DUT and the genera-
              tor.

         o    Enable OSPF on the interface between the DUT and the gen-
              erator on the DUT.

         o    Note the time of the first hello received from the DUT on
              the generator.

         o    Note the time of the acknowledgement from the DUT for the
              last LSA transmitted on the generator.

           The time between the first hello received and the ack-
           nowledgement for the last LSA transmitted by the generator
           should be taken as the total amount of time required for the
           OSPF process on the DUT to build a FULL neighbor adjacency
           with the set of LSAs injected. The acknowledgement for the
           last LSA transmitted is used instead of the last acknowledge-
           ment received in order to prevent timing skews due to
           retransmitted acknowledgements or LSAs.





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9.3. Link Up with Information Already in the Database


         o    Using reference topology 2, configure all three devices to
              run OSPF.

         o    Configure the DUT so the link between the DUT and the gen-
              erator is disabled .

         o    Inject a set of LSAs into the network from the generator;
              the DUT should receive these LSAs through normal flooding
              from the collector.

         o    Enable the link between the DUT and the generator.

         o    Note the time of the first hello received from the DUT on
              the generator.

         o    Note the time of the acknowledgement from the DUT for the
              last LSA transmitted on the generator.

           The time between the hello received from the DUT by the gen-
           erator and the acknowledgement for the last LSA transmitted
           by the generator should be taken as the total amount of time
           required for the OSPF process on the DUT to build a FULL
           neighbor adjacency with the set of LSAs injected. In this
           test, the DUT is already aware of the entire network topol-
           ogy, so the time required should only include the processing
           of each LSA from the generator and transmitting an ack-
           nowledgement. The acknowledgement for the last LSA transmit-
           ted is used instead of the last acknowledgement received in
           order to prevent timing skews due to retransmitted ack-
           nowledgements or LSAs.


9.4. Initial SR-Convergence Time on a DR electing (broadcast) network


         o    Using reference topology 3, begin with the DUT connected
              to the network with OSPF enabled. OSPF should be enabled
              on R1, but the broadcast link should be disabled.

         o    Enable the broadcast link between R1 and the DUT. Note the
              time of the first hello received by R1.

         o    Note the time the first network LSA is flooded by the DUT
              at R1.




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         o    The differential between the first hello and the first
              network LSA is the time required by the DUT to converge on
              this new topology.

           This test assumes that the DUT will be the designated router
           on the broadcast link. A similar test could be designed to
           test the SR-Convergence time when the DUT is not the desig-
           nated router as well.

           This test may be performed with varying numbers of devices
           attached to the broadcast network, and varying sets of LSAs
           being advertised to the DUT from the routers attached to the
           broadcast network. Variations in the LSA sets and other fac-
           tors shoul dbe noted in the test results.


9.5. Point-to-point Link Down with Layer 2 Detection


         o    Using reference topology 4, begin with OSPF in the full
              state between the generator and the DUT. Both links should
              be point-to-point links with the ability to notify the
              operating system immediately upon link failure.

         o    Disable link 1; this should be done in such a way that the
              keepalive timers at the data link layer will have no
              impact on the DUT recognizing the link failure (the
              operating system in the DUT should recognize this link
              failure immediately). Disconnecting the cable on the gen-
              erator end would be one possibility, or shutting the link
              down.

         o    Note the time of the link failure on the generator.

         o    At the generator, note the time of the receipt of the new
              router LSA from the DUT notifying the generator of the
              link 2 failure.

           The difference in the time between the initial link failure
           and the receipt of the LSA on the generator across link 2
           should be taken as the time required for an OSPF implementa-
           tion to recognize and process a link failure.









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9.6. Broadcast Media Link Down with Layer 3 Detection


         o    Using reference topology 4, begin with OSPF in the full
              state between the generator and the DUT.

         o    Disable OSPF processing on link 1 from the generator. This
              should be done in such a way so it does not affect link
              status; the DUT must note the failure of the adjacency
              through the dead interval.

         o    At the generator, note the time of the receipt of the new
              router LSA from the DUT notifying the generator of the
              link 2 failure.

           The difference in the time between the initial link failure
           and the receipt of the LSA on the generator across link 2
           should be taken as the time required for an OSPF implementa-
           tion to recognize and process an adjacency failure.


9.7. Designated Router Election Time on A Broadcast Network


         o    Using reference topology 3, configure R1 to be the desig-
              nated router on the link, and the DUT to be the backup
              designated router.

         o    Enable OSPF on the common broadcast link on all the
              routers in the test bed.

         o    Disble the broadcast link on R1.

         o    Note the time of the last hello received from R1 on R2.

         o    Note the time of the first network LSA generated by the
              DUT as received on R2.

           The time between the last hello received on R2 and the first
           network LSA generated by the DUT should be taken as the
           amount of time required for the DUT to complete a designated
           router election computation. Note this test includes the dead
           interval timer at the DUT, so this time can be factored out,
           or the hello and dead intervals reduced to make these timers
           impact the overall test times less. All changed timers, the
           number of routers connected to the link, and other variable
           factors should be noted in the test results.




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10. Acknowledgements

   Thanks to Howard Berkowitz, (hcb@clark.net), for his encouragement
   and support. Thanks also to Gurpreet Singh
   (Gurpreet.Singh@SpirentCom.COM) for his help as well.


11. References


 [1]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
      Levels", RFC2119, March 1997.


 [2]  Moy, J., "OSPF Version 2", RFC 2328, April 1998.


 [3]  Bradner, S., McQuaid, J., "Benchmarking Methodology for Network
      Interconnect Devices", RFC2544, March 1999.


 [4]  Manral, V., "OSPF Convergence Testing Terminiology and Concepts",
      draft-bmwg-ospfconv-term-00.txt, My 2002


 [5]  draft-alaettinoglu-isis-convergence-01.txt


 [6]  Trotter, G., "Terminology for Forwarding Information Base (FIB)
      based Router Performance", RFC3222, October 2001.


 [7]  Shaikh, Aman, Greenberg, Albert, "Experience in Black-Box OSPF
      measurement"

      >IP [8] draft-ietf-ospf-scalability-01.txt















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12. Authors' Addresses

      Vishwas Manral
      Netplane Systems
      189 Prashasan Nagar
      Road number 72
      Jubilee Hills
      Hyderabad, India

      vmanral@netplane.com

      Russ White
      Cisco Systems, Inc.
      7025 Kit Creek Rd.
      Research Triangle Park, NC 27709

      riw@cisco.com

      Aman Shaikh
      University of California
      School of Engineering
      1156 High Street
      Santa Cruz, CA  95064

      aman@soe.ucsc.edu


























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