[ns] the direction field in packet header hdr_cmn

[Yan Yu <yanyu@catarina.usc.edu>]

HI, there, 
  by looking up the mac layer code, (like mac.cc, mac-802_3.cc, or
bi-connector.cc), it seems that the MAC layer judge if it is sending or
receiving the packet( i.e., if the packet is traveling up or down the
stack) by looking up the direction field in packet header. but from my
simulation, it seems like the the direction filed is not set up
properly. I am using Mac-802_3 as MAC layer, LLSnoop as link layer..
I am wondering who is responsible for setting up the direction field in
hdr_cmn? which layer??

I guess, say, if it travels up the stack( receving a packet, physical
layer is responsible for setting it as UP. and as it travels down, the
higher layer, e.g., application layer, or network layer is reposbile for
setting it up as DOWN??

any feedback on this is very appreciated!!
yan