Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!mcsun!ukc!mucs!logitek!sadss!garethh
From: garethh@sadss (Gareth Howell )
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Subnetting a very large population
Keywords: subnetting, rfc950, rfc1219, tcp, ip
Message-ID: <98is41w163w@sadss>
Date: 19 Jun 91 13:27:19 GMT
References: <m1TF42w163w@sadss>
Organization: Department of Social Security
Lines: 36

garethh@sadss (Gareth Howell ) writes:

> Hi all,
> I wonder if someone can help me with a tricky problem I am trying to come to 
> grips with.
> 
> I have the (un)enviable taks of coming up with an Internet Addressing 
> Strategy for the UK Department of Social Security's internet (note small 
> 'i':-). This comprises (or soon will) 2500+ Ethernet LANs: each with 
> anything from 4-50 PCs, Unix application servers and gateways on them; all 
> interconnected using the Government Data Network (X.25 (1980)). Most of the 
> operational systems use OSI protocols, but there is a significant amount of 
> IP traffic, mainly for SNMP HUB and BRIDGE and host management on the LANs.
> 
I have had a couple of mail replies to this query (thanks guys), but 
unfortunately the advice has been contradictory. On the one hand I have been 
told that this will work if we use OSPF as the routing protocol (provided we 
have variable length subnet masks). On the other hand I have been told that 
this will not work as all subnets of a network must be physically connected. 

The latter was my view as well until I read Comer's book "Internetworking 
with TCPIP". In this (section 16.9) he deals with the situation where a host 
on a non-subnetted network needs to talk to one of two hosts, each of which 
is on a different, unconnected, subnet of a second network. This seems to be 
what I am trying to deal with as well.

So, the questions are, a) Is Comer section 16.9 correct? b) Must the 
individual subnets of a network be connected?
Gareth

 _____________________________________________________________________________
|                   |                                       |                 |
| EMAIL:            | ADDRESS:                              |                 |
| ukc!sadss!garethh | DSS, Moorlands Road, Lytham St Annes, | PHONE:          |
| ukc!cix!garethh   | Lancs, England.                       | +44 253 797205  |
|___________________|_______________________________________|_________________|