Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!hao!gatech!purdue!umd5!brl-adm!cmcl2!yale!leichter
From: leichter@yale.UUCP (Jerry Leichter)
Newsgroups: comp.dcom.lans
Subject: Re: LanBridge 100 multicast packets
Message-ID: <23864@yale-celray.yale.UUCP>
Date: 24 Feb 88 17:23:10 GMT
References: <2070@saturn.ucsc.edu>
Reply-To: leichter@yale-celray.UUCP (Jerry Leichter)
Organization: Yale University Computer Science Dept, New Haven CT
Lines: 23
Keywords: LB100 ethernet multicast

In article <2070@saturn.ucsc.edu> eshop@saturn.ucsc.edu (Jim Warner) writes:
>Our campus net includes one DEC LB100 lan bridge.  The LB100
>sends a packet a second of type 8038 to ether multicast address
>9:0:2b:1:0:1....Is this normal for an LB100?  Do nets that have ten LB100s have
>ten of these packets a second?  If we had RBMS, could we turn
>this off?  Do folks that have RBMS think it worth while?

These are messages that LanBridges send to each other to discover the topology
of their interconnections and build a spanning tree.  Yes, it's normal for them
to do this.  If you had 10 LanBridges, each would indeed be doing it.

I don't know if RBMS provides a way to alter this.  What it might let you do
is change the interval at which the messages are sent; I doubt it would let
you turn them off entirely.

Why would you want to turn it off anyway?  Even 10 maximum-length packets a
second would represent 1.5% or your Ethernet bandwidth - and in fact (a) the
packets are a lot smaller; (b) the packets don't pass through the bridges;
the only packets you see on any given segment are those form bridges attached
to that particular segment.  If you are designing an extended LAN with all
10 or your bridges attached to one central segment, you are going to have
other problems way before overhead for bridge control packets hurts you.

							-- Jerry