Path: utzoo!utgpu!water!watmath!clyde!att!rutgers!ucsd!ucbvax!UC.MSC.UMN.EDU!slevy From: slevy@UC.MSC.UMN.EDU ("Stuart Levy") Newsgroups: comp.protocols.tcp-ip Subject: Re: default broadcast address Message-ID: <8807101600.AA02208@uc.msc.umn.edu> Date: 10 Jul 88 16:00:57 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 15 The difficulty (for UNIX systems at least) with choosing 255.255.255.255 (or 0.0.0.0 or {net,constant,constant}) as a broadcast address arises when you try to put broadcast-based applications on multi-homed hosts or gw's. To broadcast on a particular net -- or for that matter on all nets -- what address should be used? Using the {net,subnet,constant} form at least ensures that every interface has a distinct broadcast address and that a route exists for that address. It might be possible for applications to send to {net,subnet,constant} and for the IP layer to detect that a broadcast was intended and translate it into some other broadcast address before transmission. This would be pretty disgusting, however, and is anyway not done by any software I know of. Do any of the sites choosing 255.255.255.255 as a standard broadcast address have a solution?