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rfc:rfc2889

Network Working Group R. Mandeville Request for Comments: 2889 CQOS Inc. Category: Informational J. Perser

                                                Spirent Communications
                                                           August 2000
         Benchmarking Methodology for LAN Switching Devices

Status of this Memo

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

Copyright Notice

 Copyright (C) The Internet Society (2000).  All Rights Reserved.

Table of Contents

 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  2
 3. Test setup . . . . . . . . . . . . . . . . . . . . . . . . . .  2
 4. Frame formats and sizes  . . . . . . . . . . . . . . . . . . .  3
 5. Benchmarking Tests . . . . . . . . . . . . . . . . . . . . . .  3
    5.1  Fully meshed throughput, frame loss and forwarding rates   4
    5.2  Partially meshed one-to-many/many-to-one  . . . . . . . .  7
    5.3  Partially meshed multiple devices . . . . . . . . . . . . 10
    5.4  Partially meshed unidirectional traffic . . . . . . . . . 13
    5.5  Congestion Control  . . . . . . . . . . . . . . . . . . . 16
    5.6  Forward Pressure and Maximum Forwarding Rate  . . . . . . 19
    5.7  Address caching capacity  . . . . . . . . . . . . . . . . 22
    5.8  Address learning rate . . . . . . . . . . . . . . . . . . 25
    5.9  Errored frames filtering. . . . . . . . . . . . . . . . . 27
    5.10 Broadcast frame Forwarding and Latency  . . . . . . . . . 28
 6. Security Considerations  . . . . . . . . . . . . . . . . . . . 30
 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 30
 8. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 30
    Appendix A: Formulas . . . . . . . . . . . . . . . . . . . . . 31
    Appendix B: Generating Offered Load  . . . . . . . . . . . . . 32
    Full Copyright Statement . . . . . . . . . . . . . . . . . . . 35

Mandeville & Perser Informational [Page 1] RFC 2889 LAN Switch Benchmarking Methodology August 2000

1. Introduction

 This document is intended to provide methodology for the benchmarking
 of local area network (LAN) switching devices.  It extends the
 methodology already defined for benchmarking network interconnecting
 devices in RFC 2544 [3] to switching devices.
 This RFC primarily deals with devices which switch frames at the
 Medium Access Control (MAC) layer. It provides a methodology for
 benchmarking switching devices, forwarding performance, congestion
 control, latency, address handling and filtering. In addition to
 defining the tests, this document also describes specific formats for
 reporting the results of the tests.
 A previous document, "Benchmarking Terminology for LAN Switching
 Devices" [2], defined many of the terms that are used in this
 document.  The terminology document SHOULD be consulted before
 attempting to make use of this document.

2. Requirements

 The following RFCs SHOULD be consulted before attempting to make use
 of this document: RFC 1242 [1], RFC 2285 [2], and RFC 2544 [3].
 For the sake of clarity and continuity, this RFC adopts the template
 for benchmarking tests set out in Section 26 of RFC 2544.
 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. Test setup

 This document extends the general test setup described in section 6
 of RFC 2544 [3] to the benchmarking of LAN switching devices.  RFC
 2544 [3] primarily describes non-meshed traffic where input and
 output interfaces  are grouped in mutually exclusive sending and
 receiving pairs.  In fully meshed traffic, each interface of a
 DUT/SUT is set up to both receive and transmit frames to all the
 other interfaces under test.
 Prior to each test run, the DUT/SUT MUST learn the MAC addresses used
 in the test and the address learning SHOULD be verified.  Addresses
 not learned will be forwarded as flooded frames and reduce the amount
 of correctly forwarded frames.  The rate at which address learning
 frames are offered may have to be adjusted to be as low as 50 frames
 per second or even less, to guarantee successful learning.  The
 DUT/SUT address aging time SHOULD be configured to be greater than

Mandeville & Perser Informational [Page 2] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 the period of the learning phase of the test plus the trial duration
 plus any configuration time required by the testing device.
 Addresses SHOULD NOT age out until the trial duration is completed.
 More than one learning trial may be needed for the association of the
 address to the port to occur.
 If a DUT/SUT uses a hashing algorithm with address learning, the
 DUT/SUT may not learn the necessary addresses to perform the tests.
 The format of the MAC addresses MUST be adjustable so that the
 address mapping may be re-arranged to ensure that the DUT/SUT learns
 all the addresses.

4. Frame formats and sizes

 The test frame format is defined in RFC 2544 section 8 [3] and MUST
 contain a unique signature field located in the UDP DATA area of the
 Test Frame (see Appendix C [3]).  The purpose of the signature field
 is filter out frames that are not part of the offered load.
 The signature field MUST be unique enough to identify the frames not
 originating from the DUT/SUT.  The signature field SHOULD be located
 after byte 56 (collision window [4] ) or at the end of the frame. The
 length, contents and method of detection is not defined in this memo.
 The signature field MAY have a unique identifier per port.  This
 would filter out misforwarded frames.  It is possible for a DUT/SUT
 to strip off the MAC layer, send it through its switching matrix, and
 transmit it out with the correct destination MAC address but the
 wrong payload.
 For frame sizes, refer to RFC 2544, section 9 [3].
 There are three possible frame formats for layer 2 Ethernet switches:
 standard MAC Ethernet frames, standard MAC Ethernet frames with
 vendor-specific tags added to them, and IEEE 802.3ac frames tagged to
 accommodate 802.1p&Q.  The two types of tagged frames may exceed the
 standard maximum length frame of 1518 bytes, and may not be accepted
 by the interface controllers of some DUT/SUTs. It is recommended to
 check the compatibility of the DUT/SUT with tagged frames before
 testing.
 Devices switching tagged frames of over 1518 bytes will have a
 different maximum forwarding rate than untagged frames.

5. Benchmarking Tests

 The following tests offer objectives, procedures, and reporting
 formats for benchmarking LAN switching devices.

Mandeville & Perser Informational [Page 3] RFC 2889 LAN Switch Benchmarking Methodology August 2000

5.1 Fully meshed throughput, frame loss and forwarding rates

5.1.1 Objective

 To determine the throughput, frame loss and forwarding rates of
 DUT/SUTs offered fully meshed traffic as defined in RFC 2285 [2].

5.1.2 Setup Parameters

 When offering full meshed traffic, the following parameters MUST be
 defined.  Each parameter is configured with the following
 considerations.
    Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
    1280 and 1518 bytes, per RFC 2544 section 9 [3].  The four CRC
    bytes are included in the frame size specified.
    Interframe Gap (IFG) - The IFG between frames inside a burst MUST
    be at the minimum specified by the standard (9.6 us for 10Mbps
    Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for 1 Gbps
    Ethernet) of the medium being tested.
    Duplex mode - Half duplex or full duplex.
    ILoad - Intended Load per port is expressed in a percentage of the
    medium's maximum theoretical load, regardless of traffic
    orientation or duplex mode.  Certain test configurations will
    theoretically over-subscribe the DUT/SUT.
    In half duplex, an ILoad over 50% will over-subscribe the DUT/SUT.
    Burst Size - The burst size defines the number of frames sent
    back-to-back at the minimum legal IFG [4] before pausing
    transmission to receive frames.  Burst sizes SHOULD vary between 1
    and 930 frames.  A burst size of 1 will simulate constant load
    [1].
    Addresses per port - Represents the number of addresses which are
    being tested for each port.  Number of addresses SHOULD be a
    binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
    Recommended value is 1.
    Trial Duration - The recommended Trial Duration is 30 seconds.
    Trial duration SHOULD be adjustable between 1 and 300 seconds.

Mandeville & Perser Informational [Page 4] RFC 2889 LAN Switch Benchmarking Methodology August 2000

5.1.3 Procedure

 All ports on the tester MUST transmit test frames either in a Frame
 Based or Time Based mode (Appendix B).  All ports SHOULD start
 transmitting their frames within 1% of the trial duration.  For a
 trial duration of 30 seconds, all ports SHOULD have started
 transmitting frames within 300 milliseconds of each other.
 Each port in the test MUST send test frames to all other ports in a
 round robin type fashion.  The sequence of addresses MUST NOT change
 when congestion control is applied.  The following table shows how
 each port in a test MUST transmit test frames to all other ports in
 the test.  In this example, there are six ports with 1 address per
 port:
 Source Port       Destination Ports (in order of transmission)
 Port #1           2       3       4       5       6       2...
 Port #2           3       4       5       6       1       3...
 Port #3           4       5       6       1       2       4...
 Port #4           5       6       1       2       3       5...
 Port #5           6       1       2       3       4       6...
 Port #6           1       2       3       4       5       1...
 As shown in the table, there is an equal distribution of destination
 addresses for each transmit opportunity. This keeps the test balanced
 so that one destination port is not overloaded by the test algorithm
 and all ports are equally and fully loaded throughout the test.  Not
 following this algorithm exactly will produce inconsistent results.
 For tests using multiple addresses per port, the actual port
 destinations are the same as described above and the actual
 source/destination address pairs SHOULD be chosen randomly to
 exercise the DUT/SUT's ability to perform address lookups.
 For every address, learning frames MUST be sent to the DUT/SUT to
 allow the DUT/SUT update its address tables properly.

5.1.4 Measurements

 Each port should receive the same number of test frames that it
 transmitted.  Each receiving port MUST categorize, then count the
 frames into one of two groups:
    1.) Received Frames: received frames MUST have the correct
        destination MAC address and SHOULD match a signature field.
    2.) Flood count [2].

Mandeville & Perser Informational [Page 5] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 Any frame originating from the DUT/SUT (spanning tree, SNMP, RIP,
  ...) MUST not be counted as a received frame.  Frames originating
 from the DUT/SUT MAY be counted as flooded frames or not counted at
 all.
 Frame loss rate of the DUT/SUT SHOULD be reported as defined in
 section 26.3 [3] with the following notes: Frame loss rate SHOULD be
 measured at the end of the trail duration.  The term "rate", for this
 measurement only, does not imply the units in the fashion of "per
 second."

5.1.4.1 Throughput

 Throughput measurement is defined in section 26.1 [3].  A search
 algorithm is employed to find the maximum Oload [2] with a zero Frame
 loss rate [1].  The algorithm MUST adjust Iload to find the
 throughput.

5.1.4.2 Forwarding Rate

 Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
 of test frames per second that the device is observed to successfully
 forward to the correct destination interface in response to a
 specified Oload.  The Oload MUST also be cited.
 Forwarding rate at maximum offered load (FRMOL) MUST be reported as
 the number of test frames per second that a device can successfully
 transmit to the correct destination interface in response to the MOL
 as defined in section 3.6 [2]. The MOL MUST also be cited.
 Maximum forwarding rate (MFR) MUST be reported as the highest
 forwarding rate of a DUT/SUT taken from an iterative set of
 forwarding rate measurements.  The iterative set of forwarding rate
 measurements are made by adjusting Iload.  The Oload applied to the
 device MUST also be cited.

5.1.5 Reporting format

 The results for these tests SHOULD be reported in the form of a
 graph.  The x coordinate SHOULD be the frame size, the y coordinate
 SHOULD be the test results.  There SHOULD be at least two lines on
 the graph, one plotting the theoretical and one plotting the test
 results.
 To measure the DUT/SUT's ability to switch traffic while performing
 many different address lookups, the number of addresses per port MAY
 be increased in a series of tests.

Mandeville & Perser Informational [Page 6] RFC 2889 LAN Switch Benchmarking Methodology August 2000

5.2 Partially meshed one-to-many/many-to-one

5.2.1 Objective

 To determine the throughput when transmitting from/to multiple ports
 and to/from one port. As with the fully meshed throughput test, this
 test is a measure of the capability of the DUT to switch frames
 without frame loss.  Results of this test can be used to determine
 the ability of the DUT to utilize an Ethernet port when switching
 traffic from multiple Ethernet ports.

5.2.2 Setup Parameters

 When offering bursty meshed traffic, the following parameters MUST be
 defined.  Each parameter is configured with the following
 considerations.
    Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
    1280 and 1518 bytes, per RFC 2544 section 9 [3].  The four CRC
    bytes are included in the frame size specified.
    Traffic Direction - Traffic can be generated in one direction, the
    reverse direction, or both directions.
    Interframe Gap (IFG) - The IFG between frames inside a burst MUST
    be at the minimum specified by the standard (9.6 us for 10Mbps
    Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for 1 Gbps
    Ethernet) of the medium being tested.
    Duplex mode - Half duplex or full duplex.
    ILoad - Intended Load per port is expressed in a percentage of the
    medium's maximum theoretical load, regardless of traffic
    orientation or duplex mode.  Certain test configurations will
    theoretically over-subscribe the DUT/SUT.
    In half duplex bidirectional traffic, an ILoad over 50% will
    over-subscribe the DUT/SUT.
    Burst Size - The burst size defines the number of frames sent
    back-to-back at the minimum legal IFG [4] before pausing
    transmission to receive frames.  Burst sizes SHOULD vary between 1
    and 930 frames.  A burst size of 1 will simulate constant load
    [1].

Mandeville & Perser Informational [Page 7] RFC 2889 LAN Switch Benchmarking Methodology August 2000

    Addresses per port - Represents the number of addresses which are
    being tested for each port.  Number of addresses SHOULD be a
    binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
    Recommended value is 1.
    Trial Duration - The recommended Trial Duration is 30 seconds.
    Trial duration SHOULD be adjustable between 1 and 300 seconds.

5.2.3 Procedure

 All ports on the tester MUST transmit test frames either in a Frame
 Based or Time Based mode (Appendix B).  Depending upon traffic
 direction, some or all of the ports will be transmitting.  All ports
 SHOULD start transmitting their frames within 1% of the trial
 duration.  For a trial duration of 30 seconds, all ports SHOULD have
 started transmitting frames within 300 milliseconds of each other.
 Test frames transmitted from the Many Ports MUST be destined to the
 One port.  Test frames transmitted from the One Port MUST be destined
 to the Many ports in a round robin type fashion.  See section 5.1.3
 for a description of the round robin fashion.
 For tests using multiple addresses per port, the actual port
 destinations are the same as described above and the actual
 source/destination address pairs SHOULD be chosen randomly to
 exercise the DUT/SUT's ability to perform address lookups.
      +----------+
      |          |
      |   Many   | <--------
      |          |          \
      +----------+           \
                              \
      +----------+             \               +-------------+
      |          |              ------------>  |             |
      |   Many   |  <----------------------->  |     One     |
      |          |              ------------>  |             |
      +----------+             /               +-------------+
                              /
      +----------+           /
      |          |          /
      |   Many   |  <-------
      |          |
      +----------+
 For every address, the testing device MUST send learning frames to
 allow the DUT/SUT to update its address tables properly.

Mandeville & Perser Informational [Page 8] RFC 2889 LAN Switch Benchmarking Methodology August 2000

5.2.4 Measurements

 Each receiving port MUST categorize, then count the frames into one
 of two groups:
    1.) Received Frames: received frames MUST have the correct
        destination MAC address and SHOULD match a signature field.
    2.) Flood count [2].
 Any frame originating from the DUT/SUT MUST not be counted as a
 received frame.  Frames originating from the DUT/SUT MAY be counted
 as flooded frames or not counted at all.
 Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
 of test frames per second that the device is observed to successfully
 transmit to the correct destination interface in response to a
 specified Oload.  The Oload MUST also be cited.
 Forwarding rate at maximum offered load (FRMOL) MUST be reported as
 the number of test frames per second that a device can successfully
 transmit to the correct destination interface in response to the MOL
 as defined in section 3.6 [2]. The MOL MUST also be cited.
 Maximum forwarding rate (MFR) MUST be reported as the highest
 forwarding rate of a DUT/SUT taken from an iterative set of
 forwarding rate measurements.  The iterative set of forwarding rate
 measurements are made by adjusting Iload.  The Oload applied to the
 device MUST also be cited.

5.2.5 Reporting Format

 The results for these tests SHOULD be reported in the form of a
 graph.  The x coordinate SHOULD be the frame size, the y coordinate
 SHOULD be the test results.  There SHOULD be at least two lines on
 the graph, one plotting the theoretical and one plotting the test
 results.
 To measure the DUT/SUT's ability to switch traffic while performing
 many different address lookups, the number of addresses per port MAY
 be increased in a series of tests.

Mandeville & Perser Informational [Page 9] RFC 2889 LAN Switch Benchmarking Methodology August 2000

5.3 Partially meshed multiple devices

5.3.1 Objective

 To determine the throughput, frame loss and forwarding rates of two
 switching devices equipped with multiple ports and one high speed
 backbone uplink (Gigabit Ethernet, ATM, SONET).

5.3.2 Setup Parameters

 When offering bursty partially meshed traffic, the following
 parameters MUST be defined.  Each variable is configured with the
 following considerations.
    Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
    1280 and 1518 bytes, per RFC 2544 section 9 [3].  The four CRC
    bytes are included in the frame size specified.
    Interframe Gap (IFG) - The IFG between frames inside a burst MUST
    be at the minimum specified by the standard (9.6 us for 10Mbps
    Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for 1 Gbps
    Ethernet) of the medium being tested.
    Duplex mode - Half duplex or full duplex.
    ILoad - Intended Load per port is expressed in a percentage of the
    medium's maximum theoretical load, regardless of traffic
    orientation or duplex mode.  Certain test configurations will
    theoretically over-subscribe the DUT/SUT.
    In half duplex, an ILoad over 50% will over-subscribe the DUT/SUT.
    Burst Size - The burst size defines the number of frames sent
    back-to-back at the minimum legal IFG [4] before pausing
    transmission to receive frames.  Burst sizes SHOULD vary between 1
    and 930 frames.  A burst size of 1 will simulate constant load
    [1].
    Addresses per port - Represents the number of addresses which are
    being tested for each port.  Number of addresses SHOULD be a
    binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
    Recommended value is 1.
    Trial Duration - The recommended Trial Duration is 30 seconds.
    Trial duration SHOULD be adjustable between 1 and 300 seconds.

Mandeville & Perser Informational [Page 10] RFC 2889 LAN Switch Benchmarking Methodology August 2000

    Local Traffic - A Boolean value of ON or OFF.  The frame sequence
    algorithm MAY be altered to remove local traffic.  With local
    traffic ON, the algorithm is exactly the same as a fully meshed
    throughput.  With local traffic OFF, the port sends frames to all
    other ports on the other side of the backbone uplink in a round
    robin type fashion.

5.3.3 Procedure

 All ports on the tester MUST transmit test frames either in a Frame
 Based or Time Based mode (Appendix B).  All ports SHOULD start
 transmitting their frames within 1% of the trial duration.  For a
 trial duration of 30 seconds, all ports SHOULD have started
 transmitting frames with 300 milliseconds of each other.
 Each port in the test MUST send test frames to all other ports in a
 round robin type fashion as defined in section 5.1.3.  Local traffic
 MAY be removed from the round robin list in order to send the entire
 load across the backbone uplink.
 For tests using multiple addresses per port, the actual port
 destinations are the same as described above and the actual
 source/destination address pairs SHOULD be chosen randomly to
 exercise the DUT/SUT's ability to perform address lookups.
 For every address, the testing device MUST send learning frames to
 allow the DUT/SUT to update its address tables properly.
 To measure the DUT/SUT's ability to switch traffic while performing
 many different address lookups, the number of addresses per port MAY
 be increased in a series of tests.

5.3.4 Measurements

 Each receiving port MUST categorize, then count the frames into one
 of two groups:
    1.) Received frames MUST have the correct destination MAC address
        and SHOULD match a signature field.
    2.) Flood count [2].
 Any frame originating from the DUT/SUT MUST not be counted as a
 received frame.  Frames originating from the DUT/SUT MAY be counted
 as flooded frames or not counted at all.

Mandeville & Perser Informational [Page 11] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 Frame loss rate of the DUT/SUT SHOULD be reported as defined in
 section 26.3 [3] with the following notes: Frame loss rate SHOULD be
 measured at the end of the trial duration.  The term "rate", for this
 measurement only, does not imply the units in the fashion of "per
 second."

5.3.4.1 Throughput

 Throughput measurement is defined in section 26.1 [3].  A search
 algorithm is employed to find the maximum Oload [2] with a zero Frame
 loss rate [1].  The algorithm MUST adjust Iload to find the
 throughput.

5.3.4.2 Forwarding rate

 Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
 of test frames per second that the device is observed to successfully
 forward to the correct destination interface in response to a
 specified Oload.  The Oload MUST also be cited.
 Forwarding rate at maximum offered load (FRMOL) MUST be reported as
 the number of test frames per second that a device can successfully
 transmit to the correct destination interface in response to the MOL
 as defined in section 3.6 [2]. The MOL MUST also be cited.
 Maximum forwarding rate (MFR) MUST be reported as the highest
 forwarding rate of a DUT/SUT taken from an iterative set of
 forwarding rate measurements.  The iterative set of forwarding rate
 measurements are made by adjusting Iload.  The Oload applied to the
 device MUST also be cited.

5.3.5 Reporting format

 The results for these tests SHOULD be reported in the form of a
 graph.  The x coordinate SHOULD be the frame size, the y coordinate
 SHOULD be the test results.  There SHOULD be at least two lines on
 the graph, one plotting the theoretical and one plotting the test
 results.
 To measure the DUT/SUT's ability to switch traffic while performing
 many different address lookups, the number of addresses per port MAY
 be increased in a series of tests.

Mandeville & Perser Informational [Page 12] RFC 2889 LAN Switch Benchmarking Methodology August 2000

5.4 Partially meshed unidirectional traffic

5.4.1 Objective

 To determine the throughput of the DUT/SUT when presented multiple
 streams of unidirectional traffic with half of the ports on the
 DUT/SUT are transmitting frames destined to the other half of the
 ports.

5.4.2 Setup Parameters

 The following parameters MUST be defined.  Each variable is
 configured with the following considerations.
    Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
    1280 and 1518 bytes, per RFC 2544 section 9 [3].  The four CRC
    bytes are included in the frame size specified.
    Interframe Gap (IFG) - The IFG between frames inside a burst MUST
    be at the minimum specified by the standard (9.6 us for 10Mbps
    Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for 1 Gbps
    Ethernet) of the medium being tested.
    Duplex mode - Half duplex or full duplex.
    ILoad - Intended Load per port is expressed in a percentage of the
    medium's maximum theoretical load, regardless of traffic
    orientation or duplex mode.  Certain test configurations will
    theoretically over-subscribe the DUT/SUT.
    ILoad will not over-subscribe the DUT/SUT in this test.
    Burst Size - The burst size defines the number of frames sent
    back-to-back at the minimum legal IFG [4] before pausing
    transmission to receive frames.  Burst sizes SHOULD vary between 1
    and 930 frames.  A burst size of 1 will simulate constant load
    [1].
    Addresses per port - Represents the number of addresses which are
    being tested for each port.  Number of addresses SHOULD be a
    binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
    Recommended value is 1.
    Trial Duration - The recommended Trial Duration is 30 seconds.
    Trial duration SHOULD be adjustable between 1 and 300 seconds.

Mandeville & Perser Informational [Page 13] RFC 2889 LAN Switch Benchmarking Methodology August 2000

5.4.3 Procedure

    Ports do not send and receive test frames simultaneously.  As a
    consequence, there should be no collisions unless the DUT is
    misforwarding frames, generating flooded or Spanning-Tree frames
    or is enabling some flow control mechanism.  Ports used for this
    test are either transmitting or receiving, but not both. Those
    ports which are transmitting send test frames destined to
    addresses corresponding to each of the ports receiving.  This
    creates a unidirectional mesh of traffic.
    All ports on the tester MUST transmit test frames either in a
    Frame Based or Time Based mode (Appendix B).  All ports SHOULD
    start transmitting their frames within 1% of the trial duration.
    For a trial duration of 30 seconds, all ports SHOULD have started
    transmitting frames with 300 milliseconds of each other.
    Each transmitting port in the test MUST send frames to all
    receiving ports in a round robin type fashion.  The sequence of
    addresses MUST NOT change when congestion control is applied.
    The following table shows how each port in a test MUST transmit
    test frames to all other ports in the test.  In this 8 port
    example, port 1 through 4 are transmitting and ports 5 through 8
    are receiving; each with 1 address per port:
    Source Port, then Destination Ports (in order of transmission)
    Port #1              5       6       7       8       5       6...
    Port #2              6       7       8       5       6       7...
    Port #3              7       8       5       6       7       8...
    Port #4              8       5       6       7       8       5...
    As shown in the table, there is an equal distribution of
    destination addresses for each transmit opportunity. This keeps
    the test balanced so that one destination port is not overloaded
    by the test algorithm and all receiving ports are equally and
    fully loaded throughout the test.  Not following this algorithm
    exactly will product inconsistent results.
    For tests using multiple addresses per port, the actual port
    destinations are the same as described above and the actual
    source/destination address pairs SHOULD be chosen randomly to
    exercise the DUT/SUT's ability to perform address lookups.
    For every address, the testing device MUST send learning frames to
    allow the DUT/SUT to load its address tables properly.  The
    address table's aging time SHOULD be set sufficiently longer than

Mandeville & Perser Informational [Page 14] RFC 2889 LAN Switch Benchmarking Methodology August 2000

    the learning time and trial duration time combined.  If the
    address table ages out during the test, the results will show a
    lower performing DUT/SUT.
    To measure the DUT/SUT's ability to switch traffic while
    performing many different address lookups, the number of addresses
    per port MAY be increased in a series of tests.

5.4.4 Measurements

    Each receiving port MUST categorize, then count the frames into
    one of two groups:
    1.) Received Frames: received frames MUST have the correct
        destination MAC address and SHOULD match a signature field.
    2.) Flood count [2].
 Any frame originating from the DUT/SUT MUST not be counted as a
 received frame.  Frames originating from the DUT/SUT MAY be counted
 as flooded frames or not counted at all.
 Frame loss rate of the DUT/SUT SHOULD be reported as defined in
 section 26.3 [3] with the following notes: Frame loss rate SHOULD be
 measured at the end of the trial duration.  The term "rate", for this
 measurement only, does not imply the units in the fashion of "per
 second."

5.4.4.1 Throughput

 Throughput measurement is defined in section 26.1 [3].  A search
 algorithm is employed to find the maximum Oload [2] with a zero Frame
 loss rate [1].  The algorithm MUST adjust Iload to find the
 throughput.

5.4.4.2 Forwarding rate

 Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
 of test frames per second that the device is observed to successfully
 forward to the correct destination interface in response to a
 specified Oload.  The Oload MUST also be cited.
 Forwarding rate at maximum offered load (FRMOL) MUST be reported as
 the number of test frames per second that a device can successfully
 transmit to the correct destination interface in response to the MOL
 as defined in section 3.6 [2]. The MOL MUST also be cited.

Mandeville & Perser Informational [Page 15] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 Maximum forwarding rate (MFR) MUST be reported as the highest
 forwarding rate of a DUT/SUT taken from an iterative set of
 forwarding rate measurements.  The iterative set of forwarding rate
 measurements are made by adjusting Iload.  The Oload applied to the
 device MUST also be cited.

5.4.5 Reporting format

 The results for these tests SHOULD be reported in the form of a
 graph.  The x coordinate SHOULD be the frame size, the y coordinate
 SHOULD be the test results.  There SHOULD be at least two lines on
 the graph, one plotting the theoretical and one plotting the test
 results.
 To measure the DUT/SUT's ability to switch traffic while performing
 many different address lookups, the number of addresses per port MAY
 be increased in a series of tests.

5.5 Congestion Control

5.5.1 Objective

 To determine how a DUT handles congestion.  Does the device implement
 congestion control and does congestion on one port affect an
 uncongested port.  This procedure determines if Head of Line Blocking
 and/or Backpressure are present.

5.5.2 Setup Parameters

 The following parameters MUST be defined.  Each variable is
 configured with the following considerations.
    Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
    1280 and 1518 bytes, per RFC 2544 section 9 [3].  The four CRC
    bytes are included in the frame size specified.
    Interframe Gap (IFG) - The IFG between frames inside a burst MUST
    be at the minimum specified by the standard (9.6 us for 10Mbps
    Ethernet, 960 ns for 100Mbps Ethernet, and 96 ns for 1 Gbps
    Ethernet) of the medium being tested.
    Duplex mode - Half duplex or full duplex.
    Addresses per port - Represents the number of addresses which are
    being tested for each port.  Number of addresses SHOULD be a
    binary exponential (i.e. 1, 2, 4, 8, 16, 32, 64, 128, 256, ...).
    Recommended value is 1.

Mandeville & Perser Informational [Page 16] RFC 2889 LAN Switch Benchmarking Methodology August 2000

    Trial Duration - The recommended Trial Duration is 30 seconds.
    Trial duration SHOULD be adjustable between 1 and 300 seconds.

5.5.3 Procedure

 This test MUST consist of a multiple of four ports with the same MOL.
 Four ports are REQUIRED and MAY be expanded to fully utilize the
 DUT/SUT in increments of four.  Each group of four will contain a
 test block with two of the ports as source transmitters and two of
 the ports as receivers. The diagram below depicts the flow of traffic
 between the switch ports:
      +----------+   50 % MOL                  +-------------+
      |          |  ------------------------>  |             |
      |          |   50 % MOL                  | uncongested |
      |          |  ---------                  |             |
      +----------+            \                +-------------+
                               \
                                \
                                 \
      +----------+                \            +-------------+
      |          |                 --------->  |             |
      |          |   100 % MOL                 | congested   |
      |          |  ------------------------>  |             |
      +----------+                             +-------------+
 Both source transmitters MUST transmit the exact number of test
 frames.  The first source MUST transmit test frames at the MOL with
 the destination address of the two receive ports in an alternating
 order.  The first test frame to the uncongested receive port, second
 test frame to the congested receive port, then repeat.  The second
 source transmitter MUST transmit test frames at the MOL only to the
 congested receive port.
 Both receive ports SHOULD distinguish between test frames originating
 from the source ports and frames originating from the DUT/SUT.  Only
 test frames from the source ports SHOULD be counted.
 The uncongested receive port should be receiving at a rate of half
 the MOL.  The number of test frames received on the uncongested port
 SHOULD be 50% of the test frames transmitted by the first source
 transmitter.  The congested receive port should be receiving at the
 MOL.  The number of test frames received on the congested port should
 be between 100% and 150% of the test frames transmitted by one source
 transmitter.

Mandeville & Perser Informational [Page 17] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 Test frames destined to uncongested ports in a switch device should
 not be dropped due to other ports being congested, even if the source
 is sending to both the congested and uncongested ports.

5.5.4 Measurements

 Any frame received which does not have the correct destination
 address MUST not be counted as a received frame and SHOULD be counted
 as part of a flood count.
 Any frame originating from the DUT/SUT MUST not be counted as a
 received frame.  Frames originating from the DUT/SUT MAY be counted
 as flooded frames or not counted at all.
 Frame loss rate of the DUT/SUT's congested and uncongested ports MUST
 be reported as defined in section 26.3 [3] with the following notes:
 Frame loss rate SHOULD be measured at the end of the trial duration.
 The term "rate", for this measurement only, does not imply the units
 in the fashion of "per second."
 Offered Load to the DUT/SUT MUST be reported as the number of test
 frames per second that the DUT/SUT observed to accept.  This may be
 different that the MOL.
 Forwarding rate (FR) of the DUT/SUT's congested and uncongested ports
 MUST be reported as the number of test frames per second that the
 device is observed to successfully transmit to the correct
 destination interface in response to a specified offered load. The
 offered load MUST also be cited.

5.5.5 Reporting format

 This test MUST report the frame lost rate at the uncongested port,
 the forwarding rate (at 50% offered load) at the uncongested port,
 and the frame lost rate at the congested port.  This test MAY report
 the frame counts transmitted and frame counts received by the
 DUT/SUT.

5.5.5.1 HOLB

 If there is frame loss at the uncongested port, "Head of Line"
 blocking is present.  The DUT cannot forward the amount of traffic to
 the congested port and as a result it is also losing frames destined
 to the uncongested port.

Mandeville & Perser Informational [Page 18] RFC 2889 LAN Switch Benchmarking Methodology August 2000

5.5.5.2 Back Pressure

 If there is no frame loss on the congested port, then backpressure is
 present.  It should be noted that this test expects the overall load
 to the congested port to be greater than 100%. Therefore if the load
 is greater than 100% and no frame loss is detected, then the DUT must
 be implementing a flow control mechanism.  The type of flow control
 mechanism used is beyond the scope of this memo.
 It should be noted that some DUTs may not be able to handle the 100%
 load presented at the input port. In this case, there may be frame
 loss reported at the uncongested port which is due to the load at the
 input port rather than the congested port's load.
 If the uncongested frame loss is reported as zero, but the maximum
 forwarding rate is less than 7440 (for 10Mbps Ethernet), then this
 may be an indication of congestion control being enforced by the DUT.
 In this case, the congestion control is affecting the throughput of
 the uncongested port.
 If no congestion control is detected, the expected percentage frame
 loss for the congested port is 33% at 150% overload.  It is receiving
 100% load from 1 port, and 50% from another, and can only get 100%
 possible throughput, therefore having a frame loss rate of 33%
 (150%-50%/150%).

5.6 Forward Pressure and Maximum Forwarding Rate

5.6.1 Objective

 The Forward Pressure test overloads a DUT/SUT port and measures the
 output for forward pressure [2].  If the DUT/SUT transmits frames
 with an interframe gap less than 96 bits (section 4.2.3.2.2 [4]),
 then forward pressure is detected.
 The objective of the Maximum Forwarding Rate test is to measure the
 peak value of the Forwarding Rate when the Offered Load is varied
 between the throughput [1] and the Maximum Offered Load [2].

5.6.2 Setup Parameters

 The following parameters MUST be defined.  Each variable is
 configured with the following considerations.
    Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
    1280 and 1518 bytes, per RFC 2544 section 9 [3].  The four CRC
    bytes are included in the frame size specified.

Mandeville & Perser Informational [Page 19] RFC 2889 LAN Switch Benchmarking Methodology August 2000

    Duplex mode - Half duplex or full duplex.
    Trial Duration - The recommended Trial Duration is 30 seconds.
    Trial duration SHOULD be adjustable between 1 and 300 seconds.
    Step Size - The minimum incremental resolution that the Iload will
    be incremented in frames per second.  The smaller the step size,
    the more accurate the measurement and the more iterations
    required.  As the Iload approaches the MOL, the minimum step size
    will increase because of gap resolution on the testing device.

5.6.3 Procedure

5.6.3.1 Maximum forwarding rate

 If the Throughput [1] and the MOL [2] are the same, then MFR [2] is
 equal to the MOL [2].
 This test MUST at a minimum be performed in a two-port configuration
 as described below.  Learning frames MUST be sent to allow the
 DUT/SUT to update its address tables properly.
 Test frames are transmitted to the first port (port 1) of the DUT/SUT
 at the Iload.  The FR [2] on the second port (port 2) of the DUT/SUT
 is measured.  The Iload is incremented for each Step Size to find the
 MFR.  The algorithm for the test is as follows:
  CONSTANT
    MOL = ... frames/sec; {Maximum Offered Load}
  VARIABLE
    MFR   := 0 frames/sec; {Maximum Forwarding Rate}
    ILOAD := starting throughput in frames/sec; {offered load}
    STEP  := ... frames/sec; {Step Size}
  BEGIN
    ILOAD := ILOAD - STEP;
    DO
    BEGIN
      ILOAD := ILOAD + STEP
      IF (ILOAD > MOL) THEN
      BEGIN
        ILOAD := MOL
      END
      AddressLearning; {Port 2 broadcasts with its source address}
      Transmit(ILOAD); {Port 1 sends frames to Port 2 at Offered load}
      IF (Port 2 Forwarding Rate > MFR) THEN
      BEGIN
         MFR := Port 2 Forwarding Rate; {A higher value than before}
      END

Mandeville & Perser Informational [Page 20] RFC 2889 LAN Switch Benchmarking Methodology August 2000

  END
  WHILE (ILOAD < MOL); {ILOAD has reached the MOL value}
  DONE

5.6.3.2 Minimum Interframe Gap

 The Minimum Interframe gap test SHOULD, at a minimum, be performed in
 a two-port configuration as described below.  Learning frames MUST be
 sent to allow the DUT/SUT to update its address tables properly.
 Test frames SHOULD be transmitted to the first port (port 1) of the
 DUT/SUT with an interframe gap of 88 bits.  This will apply forward
 pressure to the DUT/SUT and overload it at a rate of one byte per
 frame.  The test frames MUST be constructed with a source address of
 port 1 and a destination address of port 2.
 The FR on the second port (port 2) of the DUT/SUT is measured.  The
 measured Forwarding Rate should not exceed the medium's maximum
 theoretical utilization (MOL).

5.6.4 Measurements

 Port 2 MUST categorize, then count the frames into one of two groups:
    1.) Received Frames: received frames MUST have the correct
        destination MAC address and SHOULD match a signature field.
    2.) Flood count [2].
 Any frame originating from the DUT/SUT MUST not be counted as a
 received frame.  Frames originating from the DUT/SUT MAY be counted
 as flooded frames or not counted at all.

5.6.5 Reporting format

 MFR MUST be reported as the highest forwarding rate of a DUT/SUT
 taken from an iterative set of forwarding rate measurements. The
 Iload applied to the device MUST also be cited.
 Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
 of frames per second that the device is observed to successfully
 transmit to the correct destination interface in response to a
 specified Oload. The Iload MUST be cited and the Oload MAY be
 recorded.
 If the FR exceeds the MOL during the Minimum Interframe gap test,
 this MUST be highlighted with the expression "Forward Pressure
 detected".

Mandeville & Perser Informational [Page 21] RFC 2889 LAN Switch Benchmarking Methodology August 2000

5.7 Address Caching Capacity

5.7.1 Objective

 To determine the address caching capacity of a LAN switching device
 as defined in RFC 2285, section 3.8.1 [2].

5.7.2 Setup Parameters

 The following parameters MUST be defined.  Each variable is
 configured with the following considerations.
    Age Time - The maximum time that a DUT/SUT will keep a learned
    address in its forwarding table.
    Addresses Learning Rate - The rate at which new addresses are
    offered to the DUT/SUT to be learned.  The rate at which address
    learning frames are offered may have to be adjusted to be as low
    as 50 frames per second or even less, to guarantee successful
    learning.
    Initial Addresses - The initial number of addresses to start the
    test with.  The number MUST be between 1 and the maximum number
    supported by the implementation.

5.7.3 Procedure

 The aging time of the DUT/SUT MUST be known.  The aging time MUST be
 longer than the time necessary to produce frames at the specified
 rate.  If a low frame rate is used for the test, then it may be
 possible that sending a large amount of frames may actually take
 longer than the aging time.
 This test MUST at a minimum be performed in a three-port
 configuration described below.  The test MAY be expanded to fully
 utilized the DUT/SUT in increments of two or three ports.  An
 increment of two would include an additional Learning port and Test
 port.  An increment of three would include an additional Learning
 port, Test port, and Monitoring port.
 The Learning port (Lport) transmits learning frames to the DUT/SUT
 with varying source addresses and a fixed destination address
 corresponding to the address of the device connected to the Test port
 (Tport) of the DUT/SUT.  By receiving frames with varying source
 addresses, the DUT/SUT should learn these new addresses.  The source
 addresses MAY be in sequential order.

Mandeville & Perser Informational [Page 22] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 The Test port (Tport) of the DUT/SUT acts as the receiving port for
 the learning frames.  Test frames will be transmitted back to the
 addresses learned on the Learning port.  The algorithm for this is
 explained below.
 The Monitoring port (Mport) on the DUT/SUT acts as a monitoring port
 to listen for flooded or mis-forwarded frames.  If the test spans
 multiple broadcast domains (VLANs), each broadcast domain REQUIRES a
 Monitoring port.
 It is highly recommended that SNMP, Spanning Tree, and any other
 frames originating from the DUT/SUT be disabled when running this
 test.  If such protocols cannot be turned off, the flood count MUST
 be modified only to count test frame originating from Lport and MUST
 NOT count frames originating from the DUT/SUT.
 The algorithm for the test is as follows:
 CONSTANT
    AGE = ...;  {value greater that DUT aging time}
    MAX = ...;  {maximum address support by implementation}
  VARIABLE
    LOW  := 0;    {Highest passed valve}
    HIGH := MAX;  {Lowest failed value}
    N    := ...;  {user specified initial starting point}
  BEGIN
    DO
      BEGIN
      PAUSE(AGE);   {Age out any learned addresses}
        AddressLearning(TPort); {broadcast a frame with its source
                                Address and broadcast destination}
        AddressLearning(LPort); {N frames with varying source addresses
                                to Test Port}
      Transmit(TPort); {N frames with varying destination addresses
                         corresponding to Learning Port}
      IF (MPort receive frame != 0) OR
         (LPort receive frames < TPort transmit) THEN
        BEGIN  {Address Table of DUT/SUT was full}
          HIGH := N;
        END
      ELSE
        BEGIN  {Address Table of DUT/SUT was NOT full}
          LOW := N;
        END
      N := LOW + (HIGH - LOW)/2;
    END WHILE (HIGH - LOW >= 2);
  END {Value of N equals number of addresses supported by DUT/SUT}

Mandeville & Perser Informational [Page 23] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 Using a binary search approach, the test targets the exact number of
 addresses supported per port with consistent test iterations.  Due to
 the aging time of DUT/SUT address tables, each iteration may take
 some time during the waiting period for the addresses to clear.  If
 possible, configure the DUT/SUT for a low value for the aging time.
 Once the high and low values of N meet, then the threshold of address
 handling has been found.

5.7.4 Measurements

 Whether the offered addresses per port was successful forwarded
 without flooding.

5.7.5 Reporting format

 After the test is run, results for each iteration SHOULD be displayed
 in a table to include:
    The number of addresses used for each test iteration (varied).
    The intended load used for each test iteration (fixed).
    Number of test frames that were offered to Tport of the DUT/SUT.
    This SHOULD match the number of addresses used for the test
    iteration.  Test frames are the frames sent with varying
    destination addresses to confirm that the DUT/SUT has learned all
    of the addresses for each test iteration.
    The flood count on Tport during the test portion of each test.  If
    the number is non-zero, this is an indication of the DUT/SUT
    flooding a frame in which the destination address is not in the
    address table.
    The number of frames correctly forwarded to test Lport during the
    test portion of the test.  Received frames MUST have the correct
    destination MAC address and SHOULD match a signature field.  For a
    passing test iteration, this number should be equal to the number
    of frames transmitted by Tport.
    The flood count on Lport during the test portion of each test.  If
    the number is non-zero, this is an indication of the DUT/SUT
    flooding a frame in which the destination address is not in the
    address table.

Mandeville & Perser Informational [Page 24] RFC 2889 LAN Switch Benchmarking Methodology August 2000

    The flood count on Mport.  If the value is not zero, then this
    indicates that for that test iteration, the DUT/SUT could not
    determine the proper destination port for that many frames.  In
    other words, the DUT/SUT flooded the frame to all ports since its
    address table was full.

5.8 Address Learning Rate

5.8.1 Objective

 To determine the rate of address learning of a LAN switching device.

5.8.2 Setup Parameters

 The following parameters MUST be defined.  Each variable is
 configured with the following considerations.
    Age Time - The maximum time that a DUT/SUT will keep a learned
    address in its forwarding table.
    Initial Addresses Learning Rate - The starting rate at which new
    addresses are offered to the DUT/SUT to be learned.
    Number of Addresses - The number of addresses that the DUT/SUT
    must learn.  The number MUST be between 1 and the maximum number
    supported by the implementation.  It is recommended no to exceed
    the address caching capacity found in section 5.9

5.8.3 Procedure

 The aging time of the DUT/SUT MUST be known.  The aging time MUST be
 longer than the time necessary to produce frames at the specified
 rate.  If a low frame rate is used for the test, then it may be
 possible that sending a large amount of frames may actually take
 longer than the aging time.
 This test MUST at a minimum be performed in a three-port
 configuration in section 5.9.3.  The test MAY be expanded to fully
 utilized the DUT/SUT in increments of two or three ports.  An
 increment of two would include an additional Learning port and Test
 port.  An increment of three would include an additional Learning
 port, Test port, and Monitoring port.
 An algorithm similar to the one used to determine address caching
 capacity can be used to determine the address learning rate.  This
 test iterates the rate at which address learning frames are offered

Mandeville & Perser Informational [Page 25] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 by the test device connected to the DUT/SUT.  It is recommended to
 set the number of addresses offered to the DUT/SUT in this test to
 the maximum caching capacity.
 The address learning rate might be determined for different numbers
 of addresses but in each test run, the number MUST remain constant
 and SHOULD be equal to or less than the maximum address caching
 capacity.

5.8.4 Measurements

 Whether the offered addresses per port were successful forwarded
 without flooding at the offered learning rate.

5.8.5 Reporting format

 After the test is run, results for each iteration SHOULD be displayed
 in a table:
    The number of addresses used for each test iteration (fixed).
    The intended load used for each test iteration (varied).
    Number of test frames that were transmitted by Tport.  This SHOULD
    match the number of addresses used for the test iteration.  Test
    frames are the frames sent with varying destination addresses to
    confirm that the DUT/SUT has learned all of the addresses for each
    test iteration.
    The flood count on Tport during the test portion of each test.  If
    the number is non-zero, this is an indication of the DUT/SUT
    flooding a frame in which the destination address is not in the
    address table.
    The number of frames correctly forwarded to test Lport during the
    test portion of the test.  Received frames MUST have the correct
    destination MAC address and SHOULD match a signature field.  For a
    passing test iteration, this number should be equal to the number
    of frames transmitted by Tport.
    The flood count on Lport during the test portion of each test.  If
    the number is non-zero, this is an indication of the DUT/SUT
    flooding a frame in which the destination address is not in the
    address table.

Mandeville & Perser Informational [Page 26] RFC 2889 LAN Switch Benchmarking Methodology August 2000

    The flood count on Mport.  If the value is not zero, then this
    indicates that for that test iteration, the DUT/SUT could not
    determine the proper destination port for that many frames.  In
    other words, the DUT/SUT flooded the frame to all ports since its
    address table was full.

5.9 Errored frames filtering

5.9.1 Objective

 The objective of the Errored frames filtering test is to determine
 the behavior of the DUT under error or abnormal frame conditions.
 The results of the test indicate if the DUT/SUT filters the errors,
 or simply propagates the errored frames along to the destination.

5.9.2 Setup Parameters

 The following parameters MUST be defined.  Each variable is
 configured with the following considerations.
    ILoad - Intended Load per port is expressed in a percentage of the
    medium's maximum theoretical load possible.  The actual
    transmitted frame per second is dependent upon half duplex or full
    duplex operation.  The test SHOULD be run multiple times with a
    different load per port in each case.
    Trial Duration - The recommended Trial Duration is 30 seconds.
    Trial duration SHOULD be adjustable between 1 and 300 seconds.

5.9.3 Procedure

 Each of the illegal frames for Ethernet MUST be checked:
 Oversize - The DUT/SUT MAY filter frames larger than 1518 bytes from
 being propagated through the DUT/SUT section 4.2.4.2.1 [4].
 Oversized frames transmitted to the DUT/SUT should not be forwarded.
 DUT/SUT supporting tagged Frames MAY forward frames up to and
 including 1522 bytes long (section 4.2.4.2.1 [5]).
 Undersize - The DUT/SUT MUST filter frames less than 64 bytes from
 being propagated through the DUT/SUT (section 4.2.4.2.2 [4]).
 Undersized frames (or collision fragments) received by the DUT/SUT
 must not be forwarded.
 CRC Errors - The DUT/SUT MUST filter frames that fail the Frame Check
 Sequence Validation (section 4.2.4.1.2 [4]) from being propagated
 through the DUT/SUT.  Frames with an invalid CRC transmitted to the
 DUT/SUT should not be forwarded.

Mandeville & Perser Informational [Page 27] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 Dribble Bit Errors - The DUT/SUT MUST correct and forward frames
 containing dribbling bits.  Frames transmitted to the DUT/SUT that do
 not end in an octet boundary but contain a valid frame check sequence
 MUST be accepted by the DUT/SUT (section 4.2.4.2.1 [4]) and forwarded
 to the correct receive port with the frame ending in an octet
 boundary (section 3.4 [4]).
 Alignment Errors - The DUT/SUT MUST filter frames that fail the Frame
 Check Sequence Validation AND do not end in an octet boundary.  This
 is a combination of a CRC error and a Dribble Bit error.  When both
 errors are occurring in the same frame, the DUT/SUT MUST determine
 the CRC error takes precedence and filters the frame (section
 4.2.4.1.2 [4]) from being propagated.

5.9.5 Reporting format

 For each of the error conditions in section 5.6.3, a "pass" or "fail"
 MUST be reported.  Actual frame counts MAY be reported for diagnostic
 purposes.

5.10 Broadcast frame Forwarding and Latency

5.10.1 Objective

 The objective of the Broadcast Frame Forwarding and Latency Test is
 to determine the throughput and latency of the DUT when forwarding
 broadcast traffic.  The ability to forward broadcast frames will
 depend upon a specific function built into the device for that
 purpose.  It is therefore necessary to determine the ability of
 DUT/SUT to handle broadcast frames, since there may be many different
 ways of implementing such a function.

5.10.2 Setup Parameters

 The following parameters MUST be defined.  Each variable is
 configured with the following considerations.
    Frame Size - Recommended frame sizes are 64, 128, 256, 512, 1024,
    1280 and 1518 bytes, per RFC 2544 section 9 [3].  The four CRC
    bytes are included in the frame size specified.
    Duplex mode - Half duplex or full duplex.
    ILoad - Intended Load per port is expressed in a percentage of the
    medium's maximum theoretical load, regardless of traffic
    orientation or duplex mode.  Certain test configurations will
    theoretically over-subscribe the DUT/SUT.

Mandeville & Perser Informational [Page 28] RFC 2889 LAN Switch Benchmarking Methodology August 2000

    ILoad will not over-subscribe the DUT/SUT in this test.
    Trial Duration - The recommended Trial Duration is 30 seconds.
    Trial duration SHOULD be adjustable between 1 and 300 seconds.

5.10.3 Procedure

 For this test, there are two parts to be run.
 Broadcast Frame Throughput - This portion of the test uses a single
 source test port to transmit test frames with a broadcast address
 using the frame specified in RFC 2544 [3].  Selected receive ports
 then measure the forwarding rate and Frame loss rate.
 Broadcast Frame Latency - This test uses the same setup as the
 Broadcast Frame throughput, but instead of a large stream of test
 frames being sent, only one test frame is sent and the latency to
 each of the receive ports are measured in seconds.

5.10.4 Measurements

 Frame loss rate of the DUT/SUT SHOULD be reported as defined in
 section 26.3 [3] with the following notes: Frame loss rate SHOULD be
 measured at the end of the trial duration.  The term "rate", for this
 measurement only, does not imply the units in the fashion of "per
 second."
 Forwarding rate (FR) of the DUT/SUT SHOULD be reported as the number
 of test frames per second that the device is observed to successfully
 forward to the correct destination interface in response to a
 specified Oload.  The Oload MUST also be cited.

5.10.5 Reporting format

 The results for these tests SHOULD be reported in the form of a
 graph.  The x coordinate SHOULD be the frame size, the y coordinate
 SHOULD be the test results.  There SHOULD be at least two lines on
 the graph, one plotting the theoretical and one plotting the test
 results.
 To measure the DUT/SUT's ability to switch traffic while performing
 many different address lookups, the number of addresses per port MAY
 be increased in a series of tests.

Mandeville & Perser Informational [Page 29] RFC 2889 LAN Switch Benchmarking Methodology August 2000

6. Security Considerations

 As this document is solely for the purpose of providing metric
 methodology and describes neither a protocol nor a protocol's
 implementation, there are no security considerations associated with
 this document.

7. References

 [1]   Bradner, S., Editor, "Benchmarking Terminology for Network
       Interconnection Devices", RFC 1242, July 1991.
 [2]   Mandeville, R., "Benchmarking Terminology for LAN Switching
       Devices", RFC 2285, February 1998.
 [3]   Bradner, S. and J. McQuaid, "Benchmarking Methodology for
       Network Interconnect Devices", RFC 2544, March 1999.
 [4]   ANSI/IEEE, "CSMA/CD Access Method and Physical Layer
       Specifications," ISO/IEC 8802-3, ISBN 0-7381-0330-6, 1998.
 [5]   IEEE Draft, "Frame Extensions for Virtual Bridged Local Area
       Networks (VLAN) Tagging on 802.3 Networks", 802.3ac/D3.1, July
       1998.

8. Authors' Addresses

 Robert Mandeville
 CQOS Inc.
 21 Technology
 Irvine, CA 92618
 USA
 Phone: +1 (949) 400-4444
 EMail: bob@cqos.com
 Jerry Perser
 Spirent Communications
 26750 Agoura Road
 Calabasas, CA 91302
 USA
 Phone: + 1 818 676 2300
 EMail: jerry_perser@netcomsystems.com

Mandeville & Perser Informational [Page 30] RFC 2889 LAN Switch Benchmarking Methodology August 2000

Appendix A: Formulas

A.1 Calculating the InterBurst Gap

 IBG is defined in RFC 2285 [2] as the interval between two bursts.
 To achieve a desired load, the following Input Parameter need to be
 defined:
   LENGTH - Frame size in bytes including the CRC.
   LOAD   - The intended load in percent.  Range is 0 to 100.
   BURST  - The number of frames in the burst (integer value).
   SPEED  - media's speed in bits/sec
               Ethernet is 10,000,000 bits/sec
               Fast Ethernet is 100,000,000 bits/sec
               Gigabit Ethernet is 1,000,000,000 bits/sec
   IFG    - A constant 96 bits for the minimum interframe gap.
 The IBG (in seconds) can be calculated:
        [(100/LOAD - 1) * BURST * (IFG + 64 + 8*LENGTH)] + IFG
 IBG = -----------------------------------------------------------
                                SPEED

A.2 Calculating the Number of Bursts for the Trial Duration

 The number of bursts for the trial duration is rounded up to the
 nearest integer number.  The follow Input Parameter need to be
 defined:
   LENGTH - Frame size in bytes including the CRC.
   BURST  - The number of frames in the burst (integer value).
   SPEED  - media's speed in bits/sec
               Ethernet is 10,000,000 bits/sec
               Fast Ethernet is 100,000,000 bits/sec
               Gigabit Ethernet is 1,000,000,000 bits/sec
   IFG    - A constant 96 bits for the minimum interframe gap.
   IBG    - Found in the above formula
   DURATION - Trial duration in seconds.

Mandeville & Perser Informational [Page 31] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 An intermediate number of the Burst duration needs to be calculated
 first:
  TXTIME  =  -----------------------------------------
                             SPEED
 Number of Burst for the Trial Duration (rounded up):
                   DURATION
  #OFBURSTS =   --------------
                (TXTIME + IBG)
 Example:
   LENGTH   = 64  bytes per frame
   LOAD     = 100 % offered load
   BURST    = 24  frames per burst
   SPEED    = 10  Mbits/sec (Ethernet)
   DURATION = 10  seconds test
  IBG       = 1612.8 uS
    TXTIME    = 1603.2 uS
  #OFBURSTS = 3110

Appendix B: Generating Offered Load

 In testing, the traffic generator is configured with the Iload
 (Intended Load) and measures the Oload (Offered Load).  If the
 DUT/SUT applies congestion control, then the Iload and the Oload are
 not the same value. The question arises, how to generate the Oload?
 This appendix will describe two different methods.
 The unit of measurement for Oload is bits per second.  The two
 methods described here will hold one unit constant and let the
 DUT/SUT vary the other unit.  The traffic generator SHOULD specify
 which method it uses.

B.1 Frame Based Load

 Frame Based Load holds the number of bits constant.  The Trial
 Duration will vary based upon congestion control.  Advantage is
 implementation is a simple state machine (or loop).  The disadvantage
 is that Oload needs to be measured independently.

Mandeville & Perser Informational [Page 32] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 All ports on the traffic generator MUST transmit the exact number of
 test frames.  The exact number of test frames is found by multiplying
 the Iload of the port by the Trial Duration.  All ports MAY NOT
 transmit the same number of frames if their Iload is not the same.
 An example would be the Partially meshed many-to-one test.
 All ports SHOULD start transmitting their frames within 1% of the
 trial duration.  For a trial duration of 30 seconds, all ports SHOULD
 have started transmitting frames within 300 milliseconds of each
 other.
 The reported Oload SHOULD be the average during the Trial Duration.
 If the traffic generator continues to transmit after the Trial
 Duration due to congestion control, Oload MAY be averaged over the
 entire transmit time.  Oload for the DUT/SUT MUST be the aggregate of
 all the Oloads per port.  Oload per port MAY be reported.

B.2 Time Based Load

 Time based load holds the Trial Duration constant, while allowing the
 number of octets transmitted to vary.  Advantages are an accurate
 Trial Duration and integrated Oload measurement.  Disadvantage is
 that the starting and stopping of the traffic generator MUST be more
 accurate.
 All ports on the traffic generator are configured to transmit the
 Iload for a finite amount of time.  Each port MUST count the number
 of octets successfully transmitted.
 The start and stop is initiated at a layer defined by the test
 parameters.  The layer can be the MAC layer, IP layer, or some other
 point in the protocol stack.  The traffic generator MUST complete its
 layer specific transmit process when the stop time is reached (i.e.
 no fragments, finish the frame).
 All ports MUST start transmitting their frames within 1% of the trial
 duration.  For a trial duration of 30 seconds, all ports SHOULD have
 started transmitting frames within 300 milliseconds of each other.
 All ports SHOULD stop transmitting frames after the specified trail
 duration within 0.01% of the trial duration.  Each port's stop time
 MUST be reference to its start time.  This trial duration error
 controls the accuracy of the Oload measurement and SHOULD be reported
 with the Oload measurement.
 Each port is allowed an offset error of 0.1% and a trial duration
 error of 0.01%.

Mandeville & Perser Informational [Page 33] RFC 2889 LAN Switch Benchmarking Methodology August 2000

 Oload is found by taking the number of octets successfully
 transmitted and dividing by the trial duration.  Oload for the
 DUT/SUT MUST be the aggregate of all the Oloads per port.  Oload per
 port MAY be reported for diagnostic purposes.

Mandeville & Perser Informational [Page 34] RFC 2889 LAN Switch Benchmarking Methodology August 2000

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Mandeville & Perser Informational [Page 35]

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