Date: Wed, 16 Apr 1997 23:42:31 -0700 (PDT) From: Pete Carah <pete@ns.altadena.net> To: ghelmer@cs.iastate.edu (Guy Helmer) Cc: questions@freebsd.org Subject: Re: Subnets of all 0's/all 1's Message-ID: <199704170642.XAA11875@ns.altadena.net> In-Reply-To: <Pine.HPP.3.96.970415104251.15425D-100000@sunfire.cs.iastate.edu> from Guy Helmer at "Apr 15, 97 10:50:30 am"
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> I'm helping a FreeBSD system administrator whose class C network is > subnetted at 255.255.255.192. He would dearly like to use the subnet with > systems numbered x.x.x.1-63; I have held up RFC 950 to say "this isn't > allowed", but the RFC doesn't say specifically why this wouldn't work. Most routers support it but require a specific request (default-override) to do so. (we use both Cisco and Wellfleet - aside; if anyone can tell me how to get the "local-preference" set up to make IBGP work between a cisco and a wellfleet can they please inform me?) > Should FreeBSD be able to support a network with a subnet of all zeros or > all ones? If not, could someone give a short technical explanation as to > why? Yes, it should. I'm using several "zero-subnet" addresses currently on 2.1.7 and 2.2.1 boxes so it apparently works, at least for general users. I don't know what happens if you try to route with a box with more than one of them. The base problem is that the machine can't always tell between broadcast requests for the subnet or class-c; if the entire installation is using consistent subnet masks for the same net and NO_ONE_USES_RIP!!!, then all should work. YOU MUST NOT RUN ROUTED on a machine using 0-subnets (unless routed finally supports rip-2 and noone uses the older one). (we use gated/ospf for all fbsd-routing unless a livingston is on the net, and we keep livingstons on their own segments (and class-c blocks) for just that reason. Even a livingston can handle static-routed 0-subnets, but even at 3.5 they apparently can't handle a class-c that has more then one subnet size. -- Pete
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