Date: Thu, 12 Sep 1996 02:21:59 +0200 (MET DST) From: Jos Vissers <Jos.Vissers@telebyte.nl> To: fenner@parc.xerox.com (Bill Fenner) Cc: questions@FreeBSD.org, isp@FreeBSD.org Subject: Re: Why does arp not work when ip-alias installed Message-ID: <199609120022.CAA00961@monet.telebyte.nl> In-Reply-To: <96Sep11.090914pdt.177595@crevenia.parc.xerox.com> from "Bill Fenner" at Sep 11, 96 09:09:02 am
next in thread | previous in thread | raw e-mail | index | archive | help
Bill Fenner wrote: > >We have a network with several Livingston portmaster and a > >cisco router as gateway. Most of the dial-up ip addresses are on > >the same class c network as the servers and therefore arp -a > >should give the ethernet address of the portmaster for an > >address that is in use. > > > >It does on machines without an ip-alias. > >It doesn't on machines with ip-aliases. > > Are machines with IP aliases still able to contact these hosts? No, they cannot be reached: PING usquebauch.telebyte.nl (194.235.214.23): 56 data bytes ping: sendto: Host is down ping: wrote usquebauch.telebyte.nl 64 chars, ret=-1 This is my own machine at home, I could log in to another server and then telnet to this one so it should definitely have been reacheable. From the dial-up host the server just doesn't respond. It apparently knows how to get packets to the server, but the server doesn't know how to get them back. > What does "netstat -nr" show on the machines with aliases? Without routed it shows nothing abnormal until you ping one of the dial-up hosts that are connected at the time. It wil not show in the routing table and arp -a shows: usquebauch.telebyte.nl (194.235.214.23) at (incomplete) If I run routed it shows the portmasters ip as gateway which is correct: usquebauch pm2.nmg UGH 0 3 ed0 but arp -a doesn't show any of the dial-up hosts. It did some further testing and it only appears to happen when I add an ip-alias in another class-c network. I used "ifconfig alias 193.67.242.20 netmask 0xffffff00" and the machine's regular ip address is 194.235.214.65 When I remove the alias again it refuses to start working. The problem doesn't occurr when I define aliases in the same class-c with - of course - a netmask of 0xffffffff. Is this my error? Should I use 2 different ethernet cards when using different class-c addresses on one machine? Another of our servers with 2 cards doesn't have this problem. Thanks for the help, Jos -- Jos Vissers, System administrator Telebyte
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199609120022.CAA00961>