Link Latency Collection

Use this task to derive the link delay measurement via ping measurements from interface IP to interface IP which can be inputted into the network model. You can either collect the latency on all links in the live network model /u/wandl/data/.network/bblink.x (default) or the link latency associated with the specific devices that you select (by unchecking Collect Link Latency for all links in bblink file). Under the Count/Repeat field, enter the count for the number of pings using the CLI command option for count or repeat.

Click Next to specify the interval, for example, every 30 minutes. The maximum interval is every 5 minutes.

Figure 33: Link Latency Collection Task Window

The ping commands that were used are stored in /u/wandl/data/tmp_linklatency and the link latency file results are in /u/wandl/data/latency/YYMMDD/routername.latency.

The link latency files can be read into the network model by selecting File > Read and clicking the Network Files tab. Choose the option link latency and select your link latency directory to load at /u/wandl/data/latency/YYMMDD. Open the Map window, right-click on the background, and select Labels > Links Labels > Show Link Measured Delay to display the link latency on the topology. The link latency value is the average one-way delay in ms from Node A to Z.

Note that the dparam file, linklatencyvalue={AVG|MIN|MAX} parameter is used to determine whether to use the average, minimum, or maximum latency out of the given tries of ping, extracted from the ping command output.

Figure 34: Link Latency Map

The report for the link latency results can later be viewed on the web interface by selecting Live Network > Performance Management > Link Latency. Select Export to Excel to save this data into an excel report. By selecting a few columns, for example, Node, Interface, and a delay column, to paste into a text file, and putting in the appropriate header line, this data can be input into router config extraction via getipconf’s -delay option or input after router config extraction through modification of link properties by selecting File > Load Network Files, link data update file. See the Router Guide for more details.

Figure 35: Link Latency Report