Path: utzoo!mnetor!uunet!husc6!bloom-beacon!mit-eddie!ll-xn!ames!pasteur!ucbvax!VENERA.ISI.EDU!braden From: braden@VENERA.ISI.EDU Newsgroups: comp.protocols.tcp-ip Subject: Re: Subnetting Message-ID: <8805100150.AA07641@braden.isi.edu> Date: 10 May 88 01:50:38 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 29 It'll still seem useful, though, OK, maybe not essential for hosts to be able to find the subnet structure of a net. For sending directed broadcasts, suppose you want to say "broadcast on the net where host X lives" where X is known by name. It might be desirable to use the normal mechanism for finding X's address rather than hard-wiring an IP address into an application. In that case, since the domain name system doesn't (and shouldn't) record network structure, how could you find the right broadcast address? Admittedly this may stretch the point a bit but not too far, I think. Stuart, Directed broadcast is generally a poor idea (the right solution is the IP multicasting). No architectural decision should be taken on the grounds that it makes makes directed broadcasting easier. Likewise, if a host and several gateways are on some (sub)net, the host might want to set up its routing tables for a "good" choice of gateway to other subnets. Granting that routing should work if the host picks -some- gateway and depends on that to forward and/or redirect traffic as needed, it could still make good use of the information if it could get it. I disagree. The Internet standard approach for a host: pick any gateway and let it redirect you... is simple and effective. You REALLY DON'T want hosts to know about routing, even subnet routing!! Bob Braden