Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!swrinde!ucsd!ucbvax!hplabs!hpcc01!hpcuhb!hpindda!tozz
From: tozz@hpindda.HP.COM (Bob Tausworthe)
Newsgroups: comp.protocols.iso
Subject: Re: ESIS multicast
Message-ID: <5560072@hpindda.HP.COM>
Date: 13 Jul 90 21:11:56 GMT
References: <12183@encore.Encore.COM>
Organization: HP Information Networks, Cupertino, CA
Lines: 40

> / hpindda:comp.protocols.iso / crhodes@se-sd.SanDiego.NCR.COM (Chris Rhodes) /  4:26 pm  Jul 11, 1990 /
> 
> Under what circumstances are multicast addresses used?
> 
> Is it for Network Entity traffic only, or can multicast addresses
> be used as SNPA addresses? 
> 
> The advantage of using multicast addresses as SNPA addresses being 
> that configuration changes would not be required whenever a 
> network card is replaced in an ES or IS. A possible problem 
> however, if multiple ISs exist on the one LAN, which IS does the 
> routing?
> 
> If this is simply an implementation issue, does anyone have
> any thoughts of pros and cons of whether or not to use multicast
> addresses this way?
> 
> Regards,
> -- 
> *  Chris Rhodes, Communication Network Systems, NCR, SE-San Diego *
> *  Email Chris.Rhodes@SanDiego.NCR.COM                            *
> *  Phone (619) 693 5511   Fax (619) 693 5494                      *
> ----------

Multicast addresses are used by the ES-IS protocol for the following
functionality: Report Configuration, Query Configuration.

The multicast addresses are SNPA addresses, not Internet Addresses.

If multiple IS exist on a LAN, the ES-IS protocol states that ANY of
them do the routing. If an ES sends to an IS, and that IS decides that
another IS on the LAN is better suited to route the packet, the IS will
forward the packet to that IS and then send a Route Redirect message
to the sending ES telling it where to send subsequent packets FOR that
route.

		      Bob Tausworthe
		      Hewlett Packard
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These opinions are my own, unfortunately, not my employer's