[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 08 RFC 2432

Network Working Group                                      K. Dubray
INTERNET-DRAFT                                          Bay Networks
Expiration Date:  January 1998                             July 1997

                 Terminology for IP Multicast Benchmarking
                     <draft-ietf-bmwg-mcast-02.txt>

Status of this Memo

   This document is an Internet-Draft.  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.''

   To view the entire list of current Internet-Drafts, please check
   the "1id-abstracts.txt" listing contained in the Internet-Drafts
   Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net
   (Europe), munnari.oz.au (Pacific Rim), ds.internic.net (US East
   Coast), or ftp.isi.edu (US West Coast).

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.

Abstract

   The purpose of this draft is to add terminology specific to the
   benchmarking of multicast IP forwarding devices. It builds upon the
   tenets set forth in RFC 1242, RFC 1944, and other IETF Benchmarking
   Methodology Working Group (BMWG) effort and extends them to the
   multicast paradigm.

1.  Introduction

   Network forwarding devices are being required to take a single
   frame and support delivery to a number of destinations having
   membership to a particular group. As such, multicast support may
   place a different burden on the resources of these network
   forwarding devices than with unicast or broadcast traffic types.

   By clearly identifying benchmarks and related terminology in this
   document, it is hoped that detailed methodologies can be generated
   in subsequent documents.  Taken in tandem, these two efforts
   endeavor to assist the clinical, empirical, and consistent
   characterization of certain aspects of multicast technologies and
   their individual implementations.

   [While primarily directed towards intermediate IP multicast
   forwarding devices on LANs, elements of this text may or may not be
   applicable to other media as well.]

Dubray, K.             Expires January 1998                  [Page 1]


INTERNET-DRAFT     Multicast Benchmarking Terminology     July 1997


2.  Definition Format

   This section cites the template suggested by RFC 1242 in the
   specification of a term to be defined.

   Term to be defined.

   Definition:
      The specific definition for the term.

   Discussion:
      A brief discussion of the term, its application and any
      restrictions on measurement procedures.

   Measurement units:
      Units used to record measurements of this term, if applicable.

   [Issues:]
      List of issues or conditions that effect this term. This
      field is optional in this draft.

   [See Also:]
      List of other terms that are relevant to the discussion
      of this term. This field is optional in this draft.

2.1 Existing Terminology

   This document draws on existing terminology defined in other
   BMWG work.  Examples include, but are not limited to:

   Throughput        (RFC 1242, section 3.17)
   Latency           (RFC 1242, section 3.8)
   Constant Load     (RFC 1242, section 3.4)
   Frame Loss Rate   (RFC 1242, section 3.6)
   Overhead behavior (RFC 1242, section 3.11)
   Forwarding Rates  ([4], section 3.6)
   Loads             ([4], section 3.5)
   Devices           ([4], section 3.1)


3. Table of Defined Terms

   3.1 General Nomenclature
     3.1.1 Traffic Class.
     3.1.2 Group Class.
     3.1.3 Service Class.

   3.2 Forwarding and Throughput
     3.2.1 Mixed Class Throughput (MCT).
     3.2.2 Scaled Group Forwarding Matrix (SGFM).

Dubray, K.             Expires January 1998                  [Page 2]


INTERNET-DRAFT     Multicast Benchmarking Terminology     July 1997


     3.2.3 Aggregated Multicast Throughput (AMT)
     3.2.4 Translational Throughput (TT)

   3.3 Fairness

   3.4 Forwarding Latency
     3.4.1 Multicast Latency
     3.4.2 Min/Max Multicast Latency

   3.5 Overhead
     3.5.1 Group Join Delay.
     3.5.2 Group Leave Delay.

   3.6 Capacity
     3.6.1 Multicast Group Capacity.


3.1 General Nomenclature
   This section will present general terminology to be used in
   this and other documents.

3.1.1 Traffic Class.

   Definition:
     An equivalence class of packets comprising one or more data
     streams.

   Discussion:
     In the scope of this document, Traffic Class will be considered
     a logical identifier used to discriminate between a set or sets
     of packets offered the DUT.

     For example, one Traffic Class may identify a set of unicast packets
     offered to the DUT.  Another Traffic Class may differentiate the
     multicast packets destined to multicast group X. Yet another
     Class may distinguish the set of multicast packets destined to
     multicast group Y.

     Unless otherwise qualified, the usage of the word "Class" in this
     document will refer simply to a Traffic Class.

   Measurement units:
     Not applicable.


3.1.2 Group Class.

   Definition:
     A specific type of Traffic Class where the packets comprising the Class
     are destined to a particular multicast group.

   Discussion:



Dubray, K.             Expires January 1998                  [Page 3]


INTERNET-DRAFT     Multicast Benchmarking Terminology     July 1997


   Measurement units:
     Not applicable.


3.1.3 Service Class.

   Definition:
     A specific type of Traffic Class where the packets comprising the Class
     require particular treatment or treatments by the network
     forwarding devices along the path to the packets' destination(s).

   Discussion:

   Measurement units:
     Not applicable.

3.2 Forwarding and Throughput.

   This section presents terminology relating to the characterization of
   the packet forwarding ability of a DUT/SUT in a multicast environment.
   Some metrics extend the concept of throughput presented in RFC 1242.


3.2.1 Mixed Class Throughput (MCT).

   Definition:
     The maximum rate at which none of the offered frames, comprised
     from a unicast Class and a multicast Class, to be forwarded are
     dropped by the device.

   Discussion:
     Often times, throughput is collected on a homogenous traffic
     type - though the packets' destinations may vary, the packets
     follow the same packet forwarding path through the DUT.

     Based on the RFC 1242 definition for throughput, the Mixed
     Class Throughput benchmark attempts to characterize the DUT's
     ability to process both unicast and multicast frames in the
     same aggregated traffic stream.

   Measurement units:
     Frames per second

   Issues:
     Related methodology may have to address the ratio of unicast packets
     to multicast packets.







Dubray, K.             Expires January 1998                  [Page 4]


INTERNET-DRAFT     Multicast Benchmarking Terminology     July 1997


3.2.2 Scaled Group Forwarding Matrix (SGFM).

   Definition:
     A table that demonstrates Forwarding Rate as a function of
     tested multicast groups for a fixed number of tested
     DUT/SUT ports.

   Discussion:
     A desirable attribute of many Internet mechanisms is the ability
     to "scale." This benchmark seeks to demonstrate the ability
     of a SUT to forward as the number of multicast groups is scaled
     upwards.

   Measurement units:
     Packets per second, with corresponding tested multicast group
     and port configurations.

   Issues:
     The corresponding methodology (or even the definition itself) may
     have to reflect the impact that the pairing (source, group) has on
     many multicast routing protocols.

     Refers to the concept of Forwarding Rate originally defined in
     this document.  The definition of Forwarding Rate has been
     moved to [4].


3.2.3 Aggregated Multicast Throughput (AMT)

   Definition:
     The maximum rate at which none of the offered frames to be
     forwarded through N destination interfaces of the same multicast
     group are dropped.

   Discussion:
     Another "scaling" type of exercise, designed to identify the
     DUT/SUT's ability to handle traffic as a function of the
     multicast destination ports it is required to support.

   Measurement units:
     The ordered pair (N,t) where,

        N = the number of destination ports of the multicast group.
        t = the throughput, in frames per second, relative to the
            source stream.








Dubray, K.             Expires January 1998                  [Page 5]


INTERNET-DRAFT     Multicast Benchmarking Terminology     July 1997



3.2.4 Translational Throughput (TT)

 Definition:
     The maximum rate at which none of the frames offered in an
     transitional format to the SUT are dropped in the process of
     converting those frames to their appropriate, final format and
     subsequent correct delivery.

   Discussion:
     A popular technique in presenting frames to devices that may
     not support a protocol feature is to encapsulate, or tunnel,
     the packet containing the unsupported feature in a format that
     is supported by that device.  This benchmark attempts to
     characterize the overhead behavior associated with that
     transitional process.

     Consideration may need to be given with respect to the impact
     of different frame formats on usable bandwidth.

   Measurement units:
     Frames per second.


3.3 Fairness.

   Definition:
     The ability of a SUT to fulfill the requirements of a Traffic
     Class without compromising the requirements, if any, of other
     Classes.

   Discussion:

   Measurement units:
     Not applicable.


3.4 Forwarding Latency.

   This section presents terminology relating to the characterization of
   the forwarding latency of a DUT/SUT in a multicast environment.
   It extends the concept of latency presented in RFC 1242.


3.4.1 Multicast Latency.

   Definition:
     The set of individual latencies from a single input port on
     the DUT or SUT to all tested ports belonging to the destination
     multicast group.



Dubray, K.             Expires January 1998                  [Page 6]


INTERNET-DRAFT     Multicast Benchmarking Terminology     July 1997

   Discussion:
     This benchmark is based on the RFC 1242 definition of latency.
     While it is useful to collect latency between a pair of source
     and destination multicast ports, it may be insightful to collect
     the same type of measurements across a range of ports supporting
     that Group Class.

     A variety of statistical exercises can be applied to the set of
     latencies measurements.

   Measurement units:
     Time units with enough precision to reflect measurement.


3.4.2 Min/Max Multicast Latency.

   Definition:
     The difference between the maximum latency measurement and the
     minimum latency measurement from the set of latencies produced by
     the Multicast Latency benchmark.

   Discussion:
     This statistic may yield some insight into how a particular
     implementation handles its multicast traffic.  This may be useful
     to users of multicast synchronization types of applications.

   Measurement units:
     Time units with enough precision to reflect measurement.


3.5  Overhead

   This section presents terminology relating to the characterization of
   the overhead delays associated with explicit operations found in
   multicast environments.


3.5.1 Group Join Delay.

   Definition:
     The time duration it takes a DUT/SUT to start forwarding multicast
     packets from the time a successful IGMP group membership report has
     been issued to the DUT/SUT.

   Discussion:
     Many different factors can contribute to different results, such as
     the number or type of multicast-related protocols configured
     on the system under test.

     A consideration for the related methodology:  possible need to
     differentiate a specifically-forwarded multicast frame from those
     sprayed by protocols implementing a flooding tactic to solicit prune
     feedback.

Dubray, K.             Expires January 1998                  [Page 7]


INTERNET-DRAFT     Multicast Benchmarking Terminology     July 1997

   Measurement units:
     Microseconds.


3.5.2 Group Leave Delay.

   Definition:
     The time duration it takes a DUT/SUT to cease forwarding multicast
     packets after a corresponding IGMP "Leave Group" message has been
     successfully offered to the DUT/SUT.

   Discussion:
     While it is important to understand how quickly a system can
     process multicast frames; it may be beneficial to understand
     how quickly that same system can stop the process as well.

   Measurement units:
     Microseconds.

   Issues: Methodology may need to consider protocol-specific timeout
     values.


3.6 Capacity

   This section offers terms relating to the identification of multicast
   group limits of a DUT/SUT.

3.6.1 Multicast Group Capacity.

   Definition:
     The maximum number of multicast groups a SUT/DUT can support
     while maintaining the ability to forward multicast frames
     to all multicast groups registered to that SUT/DUT.

   Discussion:

   Measurement units:
     Multicast groups.

   Issues:
     The related methodology may have to consider the impact of multicast
     sources per group on the ability of a SUT/DUT to "scale up" the
     number of supportable multicast groups.

4. Security Considerations

   Security issues are not addressed in this memo.

5. References

   [1] Bradner, S.  Benchmarking Terminology for Network
       Interconnection Devices. RFC 1242.  July, 1991.

Dubray, K.             Expires January 1998                  [Page 8]


INTERNET-DRAFT     Multicast Benchmarking Terminology     July 1997


   [2] Bradner, S., McQuaid, J.  Benchmarking Methodology for Network
       Interconnect Devices. RFC 1944.  May, 1996.

   [3] Craig, R.  Terminology for Cell/Call Benchmarking. <draft-ietf-
       bmwg-call-01.txt> March, 1997. Work in progress.

   [4] Mandeville, R.  Benchmarking Terminology for LAN Switching
       Devices. <draft-ietf-bmwg-lanswitch-06.txt> July, 1997.
       Work in progress.

5. Author's Address

   Kevin Dubray
   Bay Networks, Inc.
   2 Federal Street
   Billerica, MA 01984
   (508) 916-3862
   kdubray@baynetworks.com

   or direct discussion to the Benchmarking Methodology Working Group:
   bmwg@harvard.edu































Dubray, K.             Expires January 1998                  [Page 9]


Html markup produced by rfcmarkup 1.129b, available from https://tools.ietf.org/tools/rfcmarkup/