Overview… source ports
The basic error checking mechanism needs only observe the test payloads in the incoming trains of packets; they could originate from any Xena tester anywhere in the network under test, possibly not even included in the current testbed.
But various other diagnostics require the XenaManager to know which port is generating the packets observed with a particular TID value, called the source port:
Since packets can take an unknown path through the system under test, determining the source port is based on a simple heuristic. The XenaManager looks at all the streams defined within the current testbed, and if there is exactly one stream using a particular TID value, then this is assumed to be the source of the packets observed at the receiver.
If no stream in the testbed uses the needed TID value then the source port is shown as “(unknown)”. If there is more than one then it is shown as “(ambiguous)”.