jc@minya.UUCP (John Chambers) (07/03/90)
Well, here I am again with Yet Another Dumb Question...
The puzzle this week, which TFM doesn't seem to help much, comes from
a client who has various sets of machines, normally each set being one
IP network or subnet, or maybe two. At times they want to interconnect
the sets via a SLIP link, and when this is done, we should set up routing
so that any machine in set A can talk to any machine in set B. Later,
and in generally overlapping, set B will be connected to set C, and any
machine in set B should talk to any machine in set C.
The tricky part that I can't answer is that they DON'T want the relation
to be transitive. In the above case, machines in set A should not be
able to communicate with those in set C. If they can, we don't get
the contract. The most important configuration will be essentially
a star, with one central set having lots of links out to other sets,
but in fact, an arbitrary graph is a better picture to plan on.
Part of the problem, of course, is that it pretty much needs to be
automated. If the solution requires any understanding of IP routing
on the part of the users, it won't work. Solutions that require a
network hacker going in as super-user on each machine and adjusting
routing tables by hand are totally outside the ballpark. We need
to provide a command of the form "Link host1 host2", which will
establish the link and set up the routing. Later on another command
may be used to shut down the link (or more likely they will just
turn the modem off and walk away ;-).
So can IP handle this? More specifically, can any of the common routing
tools (arp, routed, gated, whateverd) be used so as to get the desired
limited routing. If so, how might one do it?
I've been suggesting that they should pay me to rewrite routed and/or
gated to do the job the way they want. This would probably be fun and
profitable and all that, but I suspect that it might be a waste, since
I do sorta have this suspicion that existing tools might already be up
to the job, if I could decrypt the manuals. (Let's see, they appear to
be using mostly English words, and a syntax that is somewhat like that
of English; the cleartext is likely in an Indo-European language... ;-)
--
Uucp: ...!{harvard.edu,ima.com,eddie.mit.edu,ora.com}!minya!jc (John Chambers)
Home: 1-617-484-6393
Work: 1-508-952-3274
Cute-Saying: [I've gotta get a new one of these some day.]zsu@NISC.SRI.COM (Zaw-Sing Su) (07/03/90)
John, If I understand your problem correctly, EGP does exactly what you need for the star configuration. Make your central set the "core". For an arbitrary configuration, BGP is intended to solve the problem. Talk to Guy Alms of IETF Interoperability Working Group. Zaw-Sing
jc@minya.UUCP (John Chambers) (07/08/90)
From mail Wed Jul 4 01:45 EDT 1990 >From hp-ses.sde.hp.com!wunder Wed Jul 4 01:45:06 1990 remote from mit-eddie Received: by minya.uucp (smail2.5) id AA01293; 4 Jul 90 01:45:06 EDT (Wed) Received: from HPLABS.HPL.HP.COM by EDDIE.MIT.EDU with SMTP (5.61/25-eef) id AA25341; Tue, 3 Jul 90 11:59:31 EST Received: from hp-ses.sde.hp.com by hplabs.hpl.hp.com with SMTP (15.11.1.3/15.5+IOS 3.14) id AA16068; Tue, 3 Jul 90 09:59:40 pdt Received: by hp-ses.sde.hp.com (15.11/15.5+IOS 3.21) id AA02795; Tue, 3 Jul 90 09:59:36 pdt Date: Tue, 3 Jul 90 09:59:36 pdt From: Walter Underwood <mit-eddie!hp-ses.sde.hp.com!wunder> Message-Id: <9007031659.AA02795@hp-ses.sde.hp.com> To: minya!jc@eddie.mit.edu Subject: Re: Limited routing between IP networks. Newsgroups: comp.protocols.tcp-ip In-Reply-To: article <416@minya.UUCP> of Tue, 3 Jul 1990 03:28:19 GMT | You may get into silliness with making mail work, since the | destination may not be reachable. I'm sure that HP would be glad to | consult on this. Maybe not for free, but we make it work for a 20,000 | node network ... Actually, we have some Cisco gateways at work. As near as I can tell, they only work with LANs, and aren't set up to work across phone lines. The configurations we need have set (subnets) that are geographically quite remote from each other, and we are using (transient) SLIP links across the phone system to establish connectivity. If Cisco can do this, I'd be interested in finding out how (or where to look in the manuals or who to call to order any add-on stuff to make it work). -- Typos and silly ideas Copyright (C) 1990 by: Uucp: ...!{harvard.edu,ima.com,eddie.mit.edu,ora.com}!minya!jc (John Chambers) Home: 1-617-484-6393 Work: 1-508-952-3274