rfc2889.txt

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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.






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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




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      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.





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   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.




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      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.






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   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.







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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