Date: Tue, 18 Apr 1995 10:39:37 -0500 (CDT) From: Joe Greco <jgreco@brasil.moneng.mei.com> To: pete@silver.sms.fi (Petri Helenius) Cc: julian@tfs.com, hackers@FreeBSD.org Subject: Re: Routing nightmares. Message-ID: <9504181539.AA06725@brasil.moneng.mei.com> In-Reply-To: <199504181028.NAA15230@silver.sms.fi> from "Petri Helenius" at Apr 18, 95 01:28:41 pm
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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. And FreeBSD (seems to) implement this correctly, at least as far as packet routing goes. Except that most workstations (in particular I am thinking of Suns) won't really work in this scenario, if they're located on the 255.255.0.0 interface (or at least won't be able to talk to the router-separated subnet), for the reasons we've been discussing. Unless.... > > 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. Actually, this was the "solution". Getting the FreeBSD box to proxy ARP with two interfaces was a nightmarish mess and I sorta had it working, but it would eventually overwrite the information I was asking it to publish. It simply wasn't designed on a per-interface basis. Until it suddenly occurred to me to have some OTHER arbitrary workstation on the 255.255.0.0 network proxy arp for all the nodes on the 255.255.255.0 network... and all is very, very happy now. :-) ... Joe ------------------------------------------------------------------------------- Joe Greco - Systems Software Engineer, UNIX/Network Hacker, Etc. 414/362-3617 Marquette Electronics, Inc. - R&D - Milwaukee, WI jgreco@mei.com
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