Re: icmp messages

[anandr@cs.ucsb.edu (Anand P. Rangarajan)]

hi mark,
  i had to implement the same. my requirement was to
  send an icmp source quench message to source A
  whenever a router drops a packet from source A.

  the way i did it is like this:
   
   * define an ICMP agent

   * each node has an ICMP agent residing on port 0.
     this is done whenever you create the node.

   * the queueing mechanism in the router has a pointer to
	 the icmp agent in the router( you can just derive a class
	 from whatever queueing mechanism you like and add the
	 pointer field)
	 this is done when a simplex-link from the router is
	 created

   * when the queue drops a packet, it calls the 
	 sendSourceQuench(pkt) method in the icmp agent using
	 the pointer to the icmp agent.

   * since the icmp agent always resides in port 0, it is
	 easy to find the destination agent for the icmp
	 source quench pkt from the src field in "pkt"
   
   * use the send function to send the packet.


hope it helps.

-Anand
-- 
Anand P. Rangarajan                   Email: anandr@cs.ucsb.edu
Graduate Student, Comp. Science       URL  : http://www.cs.ucsb.edu/~anandr   
UCSB, CA - 93117, USA                 Phone: (805) 562 8703(H),805 893 5731(O)
> 
>  
> Folks-
> 
> I am stumped.  I want to generate an ICMP-like source quesnch
> message in ns, somehow.  But, I want there to be some sort of
> interaction with a queue.  Basically, what I want is when a bunch of
> conditions happen in the queueing routines I generate an SQ in the
> opposite direction (back to the sender).  However, from poking at
> the code for awhile, it would seem that it is very difficult to
> generate a new segment that is going in the opposite direction in
> the queueing routines.  Is that true?  Am I missing something?  Does
> anyone have a suggestion for a way to do this?
> 
> Any help/pointers would be appreciated.
> 
> allman
> 
> 
> ---
> http://roland.grc.nasa.gov/~mallman/
>