[ns] How to carry extra information in graft messages

[Zhang Zai Chen <zczhang@eee.hku.hk>]

Hi,

Suppose I have an agent at a multicast receiver.  When it sends a graft
message upstream, it calls "join-group"s of Node, mrtObject, and DM.
Eventually, the "send" cmd of mcastControlAgent is called, which
allocates a packet, and sends it to the counterpart agent at the
upstream node.

Now I want to carry some information, e.g. some flags, in graft
messages.  How should I do?  In other words, how to pass information
from my agent to the mcastControlAgent?

Thanks.

Zhang Zaichen