Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ucbvax!hplabs!hp-pcd!uoregon!jqj
From: jqj@uoregon.uoregon.edu (JQ Johnson)
Newsgroups: comp.dcom.lans
Subject: Re: RetixGate 2244 MAC Bridge - (nf)
Message-ID: <2396@uoregon.uoregon.edu>
Date: 14 Jul 88 14:42:35 GMT
References: <281@ifistg.UUCP> <3059@Portia.Stanford.EDU> <25335@oliveb.olivetti.com>
Reply-To: jqj@drizzle.UUCP (JQ Johnson)
Organization: University of Oregon, Computer Science, Eugene OR
Lines: 33

In article <25335@oliveb.olivetti.com> jerry@oliveb.UUCP (Jerry Aguirre) writes:
>	 Do you think that a
>repeater should have nework management hooks?  Isn't a bridge just a
>slightly smarter repeater?  
Yes, and the availability of network management hooks is one reason to
prefer a bridge over a repeater.  Note that a router is just a slightly
smarter bridge :-).
>
>Assuming the bridge is doing only ethernet address filtering and doesn't
>do multicast or other user specified filtering, do you need to manage it
>any more than you would manage a repeater?  
Yes.
>
>So, if one views a bridge as an inteligent repeater then what management
>tools are needed?  The only one I can think of is statistics and that
>could probably be better generated from other sources.  I mean, do you
>really trust the bridge to tell you about its own performance?
Yes, I think that traffic data is important.  A bridge is VERY useful
for analyzing (first pass) which parts of your network are getting
overloaded.  So is topology; if your bridges support automatic pruning
to build a spanning tree, you want to be able to find out what tree is
currently configured.  So is the ability to filter multicast and broadcast.
So is the ability to remotely segment your network for debugging serious
problems.

>Given the high cost of repeaters, why would someone want to use one
>instead of one of the Retix bridges?  (An honest question, I would like
>to see the tradeoffs discused.)
Retix throughput is only about half of full Ethernet bandwidth, so in
some applications you need a repeater for speed unless you want to pay
a lot more for your bridge.  Retix price is about twice that of a dumb
repeater, so in some applications you want a repeater for price.  On
the other hand, on our campus I have a dozen 2244Ms and no repeaters --
I'm using the Retix in place of a repeater.