[comp.protocols.tcp-ip] Broadcasting Adreess and Subnets

merlin@csvax.seas.smu.edu (David Hayes) (04/12/90)

In article <362@jove.dec.com> mogul@decwrl.dec.com (Jeffrey Mogul)
writes:
>Since I wrote RFC922, I've had a change of heart; I agree that multi-
>subnet broadcasts are a bad idea.  I've heard from some people that
>RFC1009 can be read to require their support, and also to require that
>if supported that one can configure them to be blocked; my reading of
>RFC1009 is that gateways are not required to support them.  At any rate,
>this is clearly an issue for the Router Requirements Working Group, and
>I hope that they rectify my error.

I'm working on a printer accounting program that runs throughout
our (subnetted) campus network.  It uses a client-server
architecture.  There are multiple, redundant servers.  I wanted
our system to be able to find the servers by broadcast, but our
cisco router doesn't forward them.  

That's at least one application for which multi-subnet broadcast
was the correct solution.  I don't think Jeff made a mistake
originally.  While any broadcast should be used sparingly, totally
prohibiting multi-subnet broadcasts needlessly deprives us of a
clean solution to my class of problem.

David Hayes	School of Engineering	Southern Methodist University
merlin@smu.edu	uunet!smu!merlin
"Here's a test to see if your job here on Earth is finished:  If you're
still here, it isn't."  -- Richard Bach, _Illusions_

mogul@decwrl.dec.com (Jeffrey Mogul) (04/13/90)

In article <16240@smunews.UUCP> merlin@csvax.seas.smu.edu (David Hayes) writes:
>In article <362@jove.dec.com> mogul@decwrl.dec.com (Jeffrey Mogul)
>writes:
>>Since I wrote RFC922, I've had a change of heart; I agree that multi-
>>subnet broadcasts are a bad idea.
>
>I'm working on a printer accounting program that runs throughout
>our (subnetted) campus network.  It uses a client-server
>architecture.  There are multiple, redundant servers.  I wanted
>our system to be able to find the servers by broadcast [...]

Well, I'm still against multi-subnet broadcasts; you should lean
on your vendors to support the Internet Group Multicast Protocol (RFC1112).

escher@Apple.COM (Michael Crawford) (04/14/90)

In article <379@jove.dec.com> mogul@decwrl.dec.com (Jeffrey Mogul) writes:
>In article <16240@smunews.UUCP> merlin@csvax.seas.smu.edu (David Hayes) writes:
>>
>>I'm working on a printer accounting program that runs throughout
>>our (subnetted) campus network.  It uses a client-server
>>architecture.  There are multiple, redundant servers.  I wanted
>>our system to be able to find the servers by broadcast [...]


Perhaps you could have the print servers register themselves with the name
server somehow, and then query the name server.
-- 
Michael D. Crawford
Oddball Enterprises
606 Modesto Avenue
Santa Cruz, CA 95060
oddball!mike@ucscc.ucsc.edu

Consulting for Apple Computer Inc.
escher@apple.com
Applelink: escher@apple.com@INTERNET#

The opinions expressed here are solely my own.