Date: Tue, 15 Apr 1997 12:12:15 -0700 (PDT) From: "Eric J. Schwertfeger" <ejs@bfd.com> To: Alec Kloss <alec@d2si.com> Cc: Guy Helmer <ghelmer@cs.iastate.edu>, freebsd-questions@FreeBSD.ORG Subject: Re: Subnets of all 0's/all 1's Message-ID: <Pine.BSF.3.95.970415114206.3771A-100000@harlie.bfd.com> In-Reply-To: <199704151739.MAA25341@d2si.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, 15 Apr 1997, Alec Kloss wrote: > > 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? > I did not know that this isn't allowed. I checked things out and RFC > certainly does imply that this is a no-no. In RFC 950, RFC 943 this > referenced as justification for this. RFC does not seem to use > imperitive language (you shall or you must) but something much less > harsh, as in > "When called for, the address zero is to be interpreted as > meaning "this", as in this network." Hmmm.... had a URL for a page at 3-com that had a wonderful writeup on this, and many other IP addressing issues, sort of an "everything you ever wanted to know and were afraid to ask" document, and it points to this restriction being because of one of the more primitive dynamic routing protocols being unable to handle these two cases. It also says that this restriction was depreciated, but I can't remember where or when. I was actually more surprized to find out you're supposed to have all subnets equal size. Unfortunately, Cisco's try to enforce both of these rules (or at least the 2501 we have does). On the other hand, our Linux firewall and the FreeBSD machines here (give me time, I want to convert it all to FreeBSD, but haven't had time to evaluate the FreeBSD equivilents of masquerading yet) talk to subnets that violate both rules. Ah, found it: http://www.3com.com/nsc/501302.html
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.BSF.3.95.970415114206.3771A-100000>