Path: utzoo!utgpu!watserv1!watmath!att!linac!uwm.edu!bionet!agate!ucbvax!CUNYVM.CUNY.EDU!PIRARD%vm1.ulg.ac.be From: PIRARD%vm1.ulg.ac.be@CUNYVM.CUNY.EDU (Andr'e PIRARD) Newsgroups: comp.protocols.tcp-ip Subject: Re: An INTERESTING problem Message-ID: <9101121156.AA18507@ucbvax.Berkeley.EDU> Date: 11 Jan 91 07:56:44 GMT References: Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 34 On Wed, 9 Jan 91 18:48:55 PST Richard L. Gralnik said: > 3. Use our Class B network number for the central net and for the > remote office nets with the 8-bit subnet mask, and use > subnetted Class C addresses for the serial lines. We think > this will work since all the Class B subnets have the same > net number and subnet mask, and since RIP only sends > (sub)net numbers and next hop addresses, the updates should > be accurate. A&Q. Configuration when routing by a pair of hosts usually provides the alternative of (1) using a network number dedicated to the serial line or (2) having each side borrow for the line interface a network address from the other side (i. e. one it uses on another interface). I bet you're allowed (2) but avoid it. PCROUTE's doc says that (1) is "PREFERRED", and that, in case (2) is used, one should "turn off RIP on this interface". TCP/IP for VM (version 1.2) seems to propose only (2) for links on SNA. For example I use home addresses 2.1 on one side and 32.1 on the other albeit 32.1 is the home address of another Ethernet interface of the latter. What are exactly the reasons favoring (1) besides saving a network number? What is the RIP concern? RIP broadcast traffic or RIP operability? I guess there's no reason for added traffic, as each host is supposed to send only its routing tables. But where goes a broadcast supposed to be sent to a network and that's received by a single host, etc... Any guru's comment? I think that (2) is safe indeed. I see no reason for keeping a network address contiguous. No more than if you were using multiple C addresses. Andr'e PIRARD SEGI, Univ. de Li`ege B26 - Sart Tilman B-4000 Li`ege 1 (Belgium) pirard@vm1.ulg.ac.be or PIRARD%BLIULG11.BITNET@CUNYVM.CUNY.EDU