Date: Thu, 7 May 1998 09:42:58 -1000 From: "Randal S. Masutani" <randal@comtest.com> To: freebsd-net@FreeBSD.ORG Cc: Richard Wackerbarth <rkw@dataplex.net> Subject: Re: Have I left something out? Message-ID: <199805071926.JAA03049@oldyeller.comtest.com> In-Reply-To: <l03130307b1751c02f492@[208.2.87.7]>
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On 5 May 98 at 15:00, Richard Wackerbarth wrote: > I set up a test network and it did not behave as I had hoped/expected. > > I wanted to have redundant connections so that if one goes down, another > can be used. > > Consider the simple case of a loop. For discussion, we will have 6 nets. > 10.0.1.0/24, 10.0.2.0/24, ..., 10.0.6.0/24. > We will join them with routers > 10.0.1.1 == 10.0.2.1 > 10.0.2.2 == 10.0.3.2 > ... > 10.0.5.5 == 10.0.6.5 > and to close the loop > 10.0.6.6 == 10.0.1.6 > > Now we bring them all up and let them exchange routing info. > All is well. > A packet from net 1 ==> net 3 goes via net 2. > A packet from net 1 ==> net 5 goes via net 6. > > Now we break the loop by declaring net 6 (or one of the router interfaces > thereon) down. > The routes reconfigure and the packet to net 5 now takes the longer (but > still available) > route via nets 2,3,4. > > However, and this is my problem, if I declared the 10.0.1.6 interface down, > I cannot reach the machine. > > Host 10.0.1.1 INSISTS that the packet go out the net 1 interface and cannot > reach 10.0.1.6. > It never finds the "backdoor", 10.0.6.6. > > Any suggestions? > > Richard Wackerbarth > Well is supposed to work that way. If you down the interface 10.0.1.6 then by definition that host is down. Host 10.0.1.1 cannot get to 10.0.1.6 by any other route, other than by its own interface 10.0.1.1 for network 10.0.1.0. What you are asking is that Host 10.0.1.1 redirect its interface for net 10.0.1.0 to route thru 10.0.2.1. This is not possible. As far as Host 10.0.1.1 is concerned it sees Host 10.0.1.6 as down. However, Host 10.0.1.1 can access the Host 10.0.6.1 indirectly as Host 10.0.6.6. Randal Masutani ------------------------------------------------------------------------- ComTest Technologies, Inc. 3049 Ualena St., Suite 1005 Honolulu, Hawaii 96819 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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