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Date: Tue, 18 Apr 1995 13:28:41 +0300
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From: Petri Helenius <pete@silver.sms.fi>
To: julian@TFS.COM (Julian Elischer)
Cc: hackers@FreeBSD.org
Subject: Re: Routing nightmares.
In-Reply-To: <m0rzqXk-0003wjC@TFS.COM>
References: <199504140914.LAA17784@uriah.heep.sax.de>
	<m0rzqXk-0003wjC@TFS.COM>
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Julian Elischer writes:
 > > 
 > > I'm not an INET expert, but ``common wisdom'' says you will have to
 > > use the same subnet mask throughout the whole net.
 > >
Incorrect nowadays. You should but you don't have to.

 > This is definitly the experience I have had......
 > it is UTTERLY AND COMPLETELY BROKEN!!!!!
 > it may be that some of the NEWER revisions of the routing control protocols
 > may fix this (MAYBE).. but I wouldn't count on it.

They do fix. A host should send a packet out the interface it has most
spesific route for. In this case, the one with mask 255.255.255.0 if the
packet is for that subnetwork, otherwise on 255.255.0.0 masked interface.
VLSM's are implemented in all major router equipment NOW. And have been
for a while.

 > anyway teh problem is outside your little enclave and
 > in the wider world..
 > 
 > (bad news I'm afraid....
 > (though you could see if you can broadcast proxy-arp
 > messages for all your internal nodes and 'attract'
 > all packets for them to your gateway :)

Proxy arp is a bad idea for most cases.

Pete