Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!swrinde!ucsd!ucbvax!ICAEN.UIOWA.EDU!dbfunk
From: dbfunk@ICAEN.UIOWA.EDU (David B Funk)
Newsgroups: comp.sys.apollo
Subject: Re: changing our net topology. advice needed.
Message-ID: <9001160934.AA00176@icaen.uiowa.edu>
Date: 16 Jan 90 08:37:18 GMT
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: Iowa Computer Aided Engineering Network, University of Iowa
Lines: 57

Herb, you say:

> We are in the midst of submitting a proposal to the big-wigs to
> obtain some more admin nodes and alter our network topology... Presently
> we have 42 Apollo's hooked up on three rings like so--->
> 
> 	O-O-O
> 
> however, we're buying approximately 30 new nodes in the next year and
> this will present us with a rather disgusting backup problem.  So we
> thought we'd alter the topology to reflect 4 rings in box formation
> like so--->
> 
> 	O-O
> 	| |
> 	O-O

    I have a silly question for you: why not configuire your network
like so --> O ? (IE have all your nodes in one ring?) Traffic around
a single ring is much faster than traffic thru gateways. A single
network is actually easier and quicker to administer if you have
reliable hardware. Do you have some hardware limitation (such as a T1
bridge) that forces you to run several small rings? I can't imagine a
need to break up such a small net except due to physical limitations.
    Our network currently is configured as 2 rings. The ring in our main
building has 100 nodes on it and has almost 4 miles of wire in it. We
average 5 to 10 million packets a day of network traffic. Our other ring
has only 35 nodes on it but they are spread out in 4 other buildings
that are connected to our main building with a total of over 3 miles of
fiber-optic cable & DFL100 modems. The only reason that I set the net up
as 2 rings was because I worried about the reliability of the fiber
links and the total ring size. I have heard of  nets larger than ours
with hundreds of nodes in one ring. So I don't think that you need to be
afraid of a large network.
    I'm curious as to what the practical limitations are for network
size: in node count, total network circumference, and network traffic.
Does anybody have experience with a ring of over 10 miles in
circumference? I heard rumor of somebody at Motorola wanting to connect
together rings that were in different parts of the country (like Texas
and Illinois).

WRT your question:
> 1) out of idle curiosity, how many nodes does each sys_admin at your
> site have to deal with?  Should I feel justified in being stressed
> out with 42 nodes at the present time?  Will I be near suicide when
> this figure approaches 80 nodes?

That depends upon a lot of things: how old & flaky is the hardware?
how many different things do you do as "sys_admin"? How much user
support do you do? How many users do you have? (is that 80 users or
800 users for those 80 nodes?)

We have 3 sys_admins (2 full time people and 2 part time) for our 135
nodes, and I find that our 2000+ users create far more heat than the
nodes.

Dave Funk