Re: Active networking in ns

[Alberto Cerpa <cerpa@isi.edu>]

On Wed, 13 Oct 1999, Polly Huang wrote:

> On Wed, 13 Oct 1999, Guillermo Rodriguez Garcia wrote:
> 
> > Hello,
> > 
> > I am developing a new protocol to be used in active
> > networks (for an introduction to active networks,
> > see http://www.tns.lcs.mit.edu/activeware). The main
> > issue in active networks is that "active nodes" in
> > the path from the source to the destination might
> > do some (user-specified) additional processing on
> > the protocol packets.
> > 
> > I have written a new agent and I attach it to the
> > nodes I want to be active, but the problem is that
> > I am not sure on how to allow intermediate nodes
> > to process to packet.
> > 
> > For example, let's say I have the following simple
> > topology:
> > 
> > n0(src) ---- n1 ---- n2(dst)
> > 
> > I attach active agents to all the nodes (n0, n1, n2)
> > and then send a packet from n0 to n2. The problem is
> > that the agent at n1 won't see the packet. I guess
> > that I could modify classifier.cc so that my packets
> > are always evaluated at each node, but I would like
> > to know if there is any way to do this without
> > modifying ns itself too much. Any suggestion ?
> 
> Guillermo,
> 
> DOes n1 intercept the packet, process it, and then decide what to
> do next (for example forward it down to n2) or n1 make a quick copy of the
> packet and process it, while the packet continues to be fowarded down
> to n2? If it's the latter, you can probably use a multicast address for
> your active network agents in n1 and n2 both to join.  That way, both
> agents are sure to receive the packet.  This is a quick and not very
> pretty hack, but you can get away with digging into the classifer.cc
> details.
> 
> just a thought,
> -Polly

And/or alternatively you could ask the folks at MIT for the code the used
in:

Improving the Performance of Distributed Applications using Active
Networks. Ulana Legedza, David Weherall and John Guttag, INFOCOM '98

Cheers,
Alberto. 

> 
> > 
> > Regards,
> > G.
> > -- 
> > Guillermo Rodriguez Garcia
> > <guille@iies.es>
> > 
> 
>