Path: utzoo!utgpu!water!watmath!clyde!rutgers!ucla-cs!zen!ucbvax!AI.AI.MIT.EDU!JBVB From: JBVB@AI.AI.MIT.EDU ("James B. VanBokkelen") Newsgroups: comp.protocols.tcp-ip Subject: Re: More than one IP (sub)network on one ethernet cable Message-ID: <301351.871217.JBVB@AI.AI.MIT.EDU> Date: 18 Dec 87 04:43:33 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The ARPA Internet Lines: 20 If a gateway is present, it should be configured as such. If there is no gateway, I can either return an error to the user, or ARP the address on the other network anyway. If it is on another subnet which has suddenly become irrelevant, re-configure and unset the subnet bits. If I ARP it, maybe it is a spurious broadcast, maybe it works. If it works, various clever bits of code that treat things routed via a gateway differently break down, but the connection probably survives. To me, the tradeoffs have seemed to favor returning the error. If the user is in the what I think to be the mainstream, he has a configuration problem, and should know about it. Our code was recently reported (by a customer) to be willing to ARP any address configured as a gateway, although it won't ARP off-net addresses if no gateway is configured. I didn't design it, but it seems reasonable. Comments? James B. VanBokkelen FTP Software