【文章內(nèi)容簡介】 results of such forwarding rate measurements.When offering bursty meshed traffic to a DUT/SUT a number of variables have to be considered. These include frame size, the number of frames within bursts, the interval between bursts as well as the distribution of load between ining and outgoing traffic. Terms related to bursts are defined in section below.Measurement units: n/aIssues:half duplex / full duplexSee Also: unidirectional traffic () bidirectional traffic () nonmeshed traffic () partially meshed traffic () burst ()北京國信網(wǎng)安信息系統(tǒng)測評技術(shù)試驗室Beijing GuoXinWangAn Information Technology Testingamp。Evaluation LaboratoryBenchmarking Terminology for LAN Switching Devices 第 8 頁 共 20 頁 intended load ()offered load () BurstsThis group of definitions applies to the intervals between frames or groups of frames offered to the DUT/SUT. BurstDefinition: A sequence of frames transmitted with the minimum legal interframe gap.Discussion: This definition follows from discussions in section of RFC1242 and section 21 of RFC 1944 which describes cases where it is useful to consider isolated frames as single frame bursts.Measurement units: n/aIssues:See Also: burst size ()interburst gap (IBG) () Burst sizeDefinition:The number of frames in a burst.Discussion: Burst size can range from one to infinity. In unidirectional traffic as well as in bidirectional or meshed traffic on full duplex interfaces there is no theoretical limit to burst length. When traffic is bidirectional or meshed bursts on half duplex media are finite since interfaces interrupt transmission intermittently to receive frames. On real works burst size will normally increase with window makes it desirable to test devices with small as well as large burst sizes.Measurement units:number of Noctet framesIssues:See Also: burst () interburst gap (IBG) ()北京國信網(wǎng)安信息系統(tǒng)測評技術(shù)試驗室Beijing GuoXinWangAn Information Technology Testingamp。Evaluation LaboratoryBenchmarking Terminology for LAN Switching Devices 第 9 頁 共 20 頁 Interburst gap (IBG)Definition:The interval between two bursts.Discussion:This definition conforms to the discussion in section 20 of RFC1944 on bursty traffic. Bidirectional and meshed traffic are inherently bursty since interfaces share their time between receiving and transmitting frames. External sources offering bursty traffic for a given frame size and burst size must adjust the interburst gap to achieve a specified average rate of frame transmission.Measurement units: nanoseconds microseconds milliseconds secondsIssues:See Also: burst () burst size () Loads This group of definitions applies to the rates at which traffic is offered to any DUT/SUT. Intended load (Iload)Definition: The number of frames per second that an external source attempts to transmit to a DUT/SUT for forwarding to a specified output interface or interfaces.Discussion: Collisions on CSMA/CD links or the action of congestion control mechanisms can effect the rate at which an external source of traffic transmits frames to a DUT/SUT. This makes it useful to distinguish the load that an external source attempts to apply toa DUT/SUT and the load it is observed or measured to apply. In the case of Ether an external source of traffic MUST implement the truncated binary exponential backoff algorithm to ensure that it is accessing the medium legally.Measurement units: bits per second Noctets per second (Noctets per second / media_maximumoctets per second) x 100北京國信網(wǎng)安信息系統(tǒng)測評技術(shù)試驗室Beijing GuoXinWangAn Information Technology Testingamp。Evaluation LaboratoryBenchmarking Terminology for LAN Switching Devices 第 10 頁 共 20 頁Issues:See Also: burst () interburst gap () offered load () Offered load (Oload)Definition: The number of frames per second that an external source can be observed or measured to transmit to a DUT/SUT for forwarding to a specified output interface or interfaces.Discussion: The load which an external device can be observed to apply to a DUT/SUT may be less than the intended load due to collisions on half duplex media or the action of congestion control makes it important to distinguish intended and offered load when analyzing the results of forwarding rate measurements using bidirectional or fully meshed traffic. Frames which are not successfully transmitted by an external source of traffic to a DUT/SUT MUST NOT be counted as transmitted frames when measuring forwarding rates. The frame count on an interface of a DUT/SUT may exceed the rate at which an external device offers frames due to the presence of spanning tree BPDUs (Bridge Protocol Data Units) on switches or SNMP frames. Such frames should be treated as modifiers as described in section 11 of RFC 1944. Offered load MUST be indicated when reporting the results of forwarding rate measurements.Measurement units: bits per second Noctets per second (Noctets per second / media_maximumoctets per second) x 100Issues: token ringSee Also: bidirectional traffic () fully meshed traffic () intended load () forwarding rate ()北京國信網(wǎng)安信息系統(tǒng)測評技術(shù)試驗室Beijing GuoXinWangAn Information Technology Testingamp。Evaluation LaboratoryBenchmarking Terminology for LAN Switching Devices 第 11 頁 共 20 頁 Maximum offered load (MOL)Definition: The highest number of frames per second that an external source can transmit to a DUT/SUT for forwarding to a specified output interface or interfaces.Discussion: The maximum load that an external device can apply to a DUT/SUT may not equal the maximum load allowed by t