[Ns-developers] network path packet tag

[Oliveri, Payton M USA CTR (US)]

We were looking to implement a way to track packets through the network from source to destination to observe the route taken. We initially set this up through a series of callbacks connected to the IP layer, identifying the original send, each forward, and the final receive; however, this very quickly degrades efficiency (it takes approx 30 times as long to run with this added load).
Our next thought was to simply develop our own packet tag, that could be removed at each new hop, that hop's id appended, and the tag re-added to the packet. However this starts to compete with PACKET_TAG_MAX_SIZE defined in packet-tag-list.h. We realize that simply increasing this value for the expected diameter of the network is very poor in terms of memory management, especially since it affects each packet tag's memory allocation.
Is there a recommended way of gathering this information? Is there a way to modify how we use our new packet tag to avoid this issue, possibly with variable length packet tags?
Thanks,
Payton Oliveri