Path: utzoo!mnetor!uunet!husc6!bu-cs!kwe From: kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) Newsgroups: comp.dcom.lans Subject: Re: Subnetting Message-ID: <22482@bu-cs.BU.EDU> Date: 9 May 88 14:24:34 GMT References: <358@halley.UUCP> <203@tekbspa.UUCP> Reply-To: kwe@buit13.bu.edu (Kent England) Followup-To: comp.dcom.lans Organization: Boston Univ. Information Tech. Dept. Lines: 38 Summary: Subnets are an important admin device In article <203@tekbspa.UUCP> joe@tekbspa.UUCP (Joe Angelo) writes: > >But what about subnetting? ... >Is subnetting just a nice admistrativia thing? Subnetting is not at all administrivia if you are trying to plug two autonomous systems together. An autonomous system is just an administrative boundary between networks. You may have many ASs within your company or campus or the chief boundary may be between your Network and the Internet. If you have ever tried just plugging some other ASs router onto your homogeneous Ethernet, you would have a feel for the grief that you and the other system admin are in for. You don't have to hide your own admin trivia behind one Class A/B network address, but it sure makes life easier. It might be smart to prepare for installing routers by subnetting addresses while still interconnecting segments with repeaters and/or bridges. You can set up a Class B with pseudo-subnetting and, at some convenient point, replace repeaters and bridges with real IP routers without having to change addresses. (Hosts that understand subnets must be properly instructed about the true network architecture. Hosts that don't understand subnets must always be fooled. :-) >Or does your local >enet board not receive the packets, period? Or is it the high >level software that ignores the packet? Does anything really ignore >anything? > If your network is not really subnetted (just looks that way), then broadcasts are still heard everywhere, your net will still meltdown, your local enet boards will still process tens of broadcasts per second. :-) Just setting up addresses to look subnetted is not subnetting, not until you actually have subnet routing. That's my view... Kent England, Boston University