[ns] Missing packets.

[hao wang]

On Tue, 9 Apr 2002, Steve wrote:

>
> Hi,
>
> There are two questions here that I missed from my previous message.
>
> Firstly, when breaking a link (using rtmodel-at 5.0 down n1 n2) without
> using rtproto DV so the traffic is not rerouted, the packets continue
> to flow into the router at the start of the link but disappear. They
> do not get put into a queue and do not continue when the link is
> re-established. It seems that any number of packets will be accepted at
> the router but they do not get processed in any way (not dropped), so
> what happens. The router continues normally when the link is back up,
> as if no packets had reached it while the link was down.
This is because the default routing for ns is static routing. See ns
manual ch25.

>
> I suppose this is because you are actually stopping the router, not the
> link, from working, so it just doesn't function in anw way.
>
> Secondly, I was wondering what would be the best technique(s) to
> use to compare the IP and MPLS network? Use rtproto DV with rtmodel-at
> and a rerouting method such as simple-dynamic as used in test-reroute.tcl,
> to reroute a broken link, or should I forget about broken links and rt*
> and just create enough traffic on the network to create heavy congestion
> where the IP network will suffer high delay and loss but I can specify
> explicit paths for the MPLS network to avoid the congestion.
The DV routing does has the ability to cope with topology changes, but it
does not has much ability to avoid congestion. It has other problems as
well.

>
> thanks,
>
> Steve
>

Hope it helps.

Hao