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    Delay Measurement File

    A link latency file can be specified as an input to getipconf using the -delay <delayFile> option. This file is used to indicate the delay measurement from nodeA to nodeZ via a particular interface on nodeA. This information will be stored in the bblink file after the config file import via getipconf. For online users, the Link Latency Task provides one way to collect delay measurement information.

    The following is an example of a link latency file with a customized header line followed by contents. In the example below, ATL and LDN2600 are connected.

    #!NodeA,Interface,LatencyA2Z,BW
    LDN2600,Ethernet0/1,50,100m
    ATL,fe-0/1/3.0,50,100m

    The format of the link latency file is flexible. The customizable column headers should be specified in a comma-separated list following a “#!”. The column headers on this line must be one of the following reserved keywords in order to be recognized.

    • NodeA, NodeZ, Interface, InterfaceZ
    • LatencyA2Z: Latency from NodeA to NodeZ (ms). For microseconds, use decimals.
    • LatencyZ2A: Latency from NodeZ to NodeA (ms). For microseconds, use decimals.
    • RoundTripLatency: This number will be divided by two to get the latency
    • BW-K: The bandwidth in K
    • BW: The bandwidth in bits
    • ISIS2Metric: The ISIS level 2 metric

    Note that the data for one link could also be represented in one line instead of two. For example, the above link latency file entry for the link between LDN2600 and ATL could be shortened to one line by including the LatencyZ2A column, as shown below:

    #!NodeA,Interface,LatencyA2Z,LatencyZ2A,BW
    LDN2600,Ethernet0/1,50,50,100m

    The RoundTripLatency could also be specified as an alternative to the Latency in one direction.

    #!NodeA,Interface,RoundTripLatency,BW
    LDN2600,Ethernet0/1,100,100m

    For backwards compatibility, the following fixed format is also supported:

    #RouterA,Type,RouterZ,Interface,Interface IP,Bandwidth(K),Metric,LatencyZ2A
    conf1,,,Ethernet0,10.0.0.1,,,10

    For the fixed format, the only attributes that are required are RouterA, Interface, and Latency, as shown in the example above. Note that the direction of Latency here is from NodeZ to NodeA.

    Modified: 2016-11-08