Roger's odd programming question of the week

[Rick Sivernell]

On Fri, 02 Sep 2005 16:21:10 +0200
Roger Oberholtzer <roger at opq.se> wrote:

> On Fri, 2005-09-02 at 15:12, Rick Sivernell wrote:
> > Roger
> > 
> > 
> >   As per my source, Unix Network Programming", the following excerpts:
> > 
> > On IPv4 & IPv6 work similarly, The app on host, receiving host, starts & creates a
> > UDP socket and binds to port 123, and joins the multicast group. MC on a single
> > lan is simple, 1 host sends a MC packet & any interested host receives it, the
> > benifit of MC over broadcast is reduced load on all interested hosts.
> > 
> > there are many more pageson this. does this help?
> 
> This I know. But it doesn't really answer the question: will a listener
> on a local broadcast address see multicast packets?
> 
> Mulitcast addresses are in the range 224.0.0.1 thru 239.255.255.255. So,
> if I am listening for broadcasts on 255.255.255.255 (on a local network
> segment!), would I see something for MC group 244.1.1.1? You might sat
> so as the masks allow it. But the multicast bits seem to be special.
> 
> BTW, to see what multicast hosts are on your net, do:
> 
> 	ping 224.0.0.1
> 
> os to check a specific card:
> 
> 	ping -I eth1 224.0.0.1
> 
> Or try
> 
> 	ping 224.0.0.2
> 
> to see if there are any MC routers on your net. 
> 
> 
> > 
> +????????????????????????????+???????????????????????????????+
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Roger

   That was a quicky, I will research farther when I have time. You most likely will
have youe question answered before then. Interesting topic.

cheers

-- 
Rick Sivernell
Dallas, Texas  75287
972 306-2296
res005ru at verizon.net
Registered Linux User