A new Maxwell plugin that can do user controlled re-sequencing of packets is available as part of the latest Maxwell TCP testing package.
The plugin is able to re-arrange packets in a flow so that, for example, packets that originate in sequence A, B, C, D, E, F will arrive in the order C, B, A, D, F, E.
The plugin allows user control of the re-sequence pattern and several other parameters.
Two scenarios have been created to allow the user to launch this plugin with a mouse click:
This plugin gives the user greater control over packet reordering than is possible using the standard jitter impairment.
Areas in which this plugin may prove useful:
The plugin works on the concept of a “group” of packets (where the group size is from 1 to 9 packets.)
For instance, the user can define a group size and specify the order in which the packets are released from the group. Thus with a group size of 4 containing packets A, B, C, and D the user could specify that they are released in order C, D, B, A.
There is another parameter to specify a number of packet between groups.
And another parameter to specify a limit on the time to accumulate the N packets of a group – if that limit is reached the group is drained, with a flag specifying whether to apply as much of the release pattern as usable, or not.
Note: re-sequencing causes packets to be delayed as they wait for the re-sequence group to be accumulated. Consequently, re-sequencing will override the effect of any delay or jitter added by the standard impairments on the flow being re-sequenced.