Return to BSD News archive
Xref: sserve comp.protocols.tcp-ip:27731 comp.unix.bsd:13497 comp.unix.ultrix:21592 Path: sserve!newshost.anu.edu.au!munnari.oz.au!constellation!news.uoknor.edu!ns1.nodak.edu!netnews.nwnet.net!pnl-oracle!osi-east2.es.net!fastrac.llnl.gov!lll-winken.llnl.gov!sol.ctr.columbia.edu!howland.reston.ans.net!pipex!uknet!signal.dra.hmg.gb!breeze.dra.hmg.gb!not-for-mail From: heading@signal.dra.hmg.gb (Anthony Heading) Newsgroups: comp.protocols.tcp-ip,comp.unix.bsd,comp.unix.ultrix Subject: How do multi-homed hosts choose the interface? Date: 24 Feb 1994 04:41:51 -0000 Organization: Defence Research Agency, UK Lines: 30 Message-ID: <2khb6f$9fl@breeze.dra.hmg.gb> NNTP-Posting-Host: breeze.dra.hmg.gb Hello. I'm really puzzled by this. We have several hundred hosts on a class B ethernet, and a few on a class C FDDI net, the routing being done by one of two machines (an OSF/1 alpha and an Ultrix DECstation) which have interfaces on both networks. The nameserver has multiple A records for these machines - we hope to avoid giving different hostnames to the different interfaces. I want the two routing machines to use the FDDI network to talk to each other, but they steadfastly refuse to use anything but the ethernet. I've tried setting the interface metrics (which doesn't work) and reversing the boot time configuration order in the hope that this might reorder the routing table (without success - netstat -r lists the class B network first always). Resorting to the obvious books, Comer vol.1 doesn't discuss DNS style multiple addresses at all, and the 4.3BSD book claims routing is a user-level process and the kernel doesn't try to do anything smart. This makes me suspect that multiple A records are used by trying each address in the gethostbyjingo() structure in turn, but there seems to be no way of making the DNS server impose order onto those addresses. Any clues, speculation or even hard answers appreciated... Thanks Anthony -- ------------------ AJR Heading, DRA UK