Re: [ns]Quick ques - prompt response will be appreciated

[Lloyd Wood <l.wood@eim.surrey.ac.uk>]

On Thu, 16 Nov 2000, Arun Gandhi wrote:

> #1. If a simple network with two paths to the destination, can I force the 
> packets to follow an explicit route. If yes, how can I implement this?

set link costs that are used in the routig calculations to compute
shortest paths. I made link cost proportional to link delay, so I was
using e.g.
[$ns link $n($node1) $n($node2)] cost $propdelaycost
with DV routing. (I put nodes in an array because I was generating a
variable number of them.)


> #2. I have a topology where in i am using DV routing. I try the experiment 
> with different traffic sources(CBR, Exponential UDP, TCP). The first two 
> works fine but TCP doesn't. Yes my immediate reaction was to change the 
> window size (default is 20 which i changed to 500). Even after doing so I 
> see nothing in the trace except for the routing information exchanged 
> between the routers. The script neither gives any errors when executed. Any 
> suggestions?

TCP is not a traffic source. Applications are traffic sources; TCP is
an agent that takes traffic from an application and does stuff to it
before passing it on. Try reading the script at the introduction to
the ns manual... my guess is that you've stumbled across and got
confused by the legacy Agent/CBR stuff before the agent/app separation
in ns, and not actually hooked up a traffic generator to TCP.

> My topology is,
> 
>   10 - 11 - 12 - 13
> /                 \
> 0 - 1 - 2 - 3 - 4 - 5
>          \	   /
> 	  6 - 7 - 8

that's not at all useful to know.

L.

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>