Re: [ns] IGMP in multicasting?

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

On Fri, 14 Dec 2001, bindumadhavi ramavarjula wrote:

> In the ns supported multicasting we give explicit join
> and leave commands from the tcl script to make a node
> join/leave the multicast group.but in IGMP we have the
> neighbourhood router continuously poll each of the
> hosts to check whether they want to be part of some
> group or not.my question is that if this is so would
> not the polling form a substantial part of the
> multicasting packet load?if it does then since ns does
> not simulate that how would we cope with that to get a
> more realistic multicasting simulation?

as far as ns multicast is concerned, each node is a router
representing a (presumed broadcast-capable) subnet, and doing
joins/leaves for the subnet; ns multicast focuses on building
multicast trees between subnets.

IGMP routers don't really poll hosts on their subnets; that's not
quite how the querier/election/timer mechanisms work.

L.

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