Date: 13 Jan 2003 09:04:18 -0500 From: Lowell Gilbert <freebsd-questions-local@be-well.no-ip.com> To: freebsd-questions@freebsd.org Subject: Re: Multiple network cards with IP addresses in the same network Message-ID: <44ptr16t99.fsf@be-well.ilk.org> In-Reply-To: <20030113114954.GQ1330@anand.org> References: <20030113114954.GQ1330@anand.org>
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Anand Buddhdev <arb@anand.org> writes: > I have a FreeBSD 4.7 system, with 3 ethernet cards. The first two > are recognised as fxp0 and fxp1 and the second as em0 (intel gigabit > card). I configured the em0 with address 192.168.0.1/24. I then wanted > to configure fxp0 with the address 192.168.0.2/24, and also connect it > to the switch so that I can connect to the server via both addresses. > However, FreeBSD's ifconfig command fails, and won't let me add the second > address to the fxp0 interface. I read the manual page about ifconfig, > and read about aliases, where it said that for aliases, I must use the > netmask /32. When I do try to add the second address with a netmask of > /32, it works, but it doesn't make sense to me. How is that interface > going to to know that it is part of a /24 network if I use a /32 netmask? > > Would anyone be kind enough to explain why: > > 1. For aliases, I need the /32 mask You don't, *unless* the address is inside of a subnet for which you already have a route. In that case, you obviously need to avoid ambiguity. > 2. Adding a second IP to a *different* network card in the same server > does not work if the second IP is within the network of the first one. Because when a packet comes in for that network, there's no way to tell which card it should go to. I think you need to rethink your network design a bit. If you have different Ethernet links, you should either bridge or route between them. If you want to route between them, they almost always should have distinct subnet ranges. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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