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From: "Thumper!" <thumper@vfr.interceptor.com>
Newsgroups: comp.unix.bsd.bsdi.misc
Subject: Re: Multiple IP networks on one interface (during switchover)?
Date: Sat, 20 Apr 1996 00:24:05 -0700
Organization: Interceptor Systems
Lines: 31
Message-ID: <31789115.6658@vfr.interceptor.com>
References: <4l6dea$mn9@Mars.mcs.com>
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To: Leslie Mikesell <les@MCS.COM>
Leslie Mikesell wrote:
>
> I am in the process of switching internet feeds and thus need to
> change my IP numbers, including that of my nameservers. During
> the switch I will have two routers connecting to the old and
> new addresses. Would it be feasible to connect the routers to
> the same ethernet and alias the nameservers' interfaces so they
> will respond to the new network address as well as the old one?
I have a client that is in the process of doing exactly that. They have
a Cisco 2501 router, and we added a second CSU/DSU and plugged the new
T1 into the second port. We're not running BGP or anything; all packets
go OUT the new T1, but we can get packets in from either side.
All I did was use ifconfig "alias" options (see the man pages for the
exact syntax) for the additional IP's (the machine is typically aliased
to 4 IPs on a gaven Class C for virtual servers).
The only trouble we've been having has been with proxy arp and out 2
dialin modems we have on com0 and com1. For shell, they're fine, but
for PPP, since we added the second class C aliases, 90 percent of the
time it fails to proxy ARP the PPP ip's when the user logs in. Since we
have a simple setup (just dynamic IP), I've just set the proxy arp into
/etc/rc.local and let it stay published whether the PPP connections are
"live" or not.
Steve
--
Thumper! Leporidae Extraordinhare
thumper@vfr.interceptor.com http://www.interceptor.com/~thumper
"Life is to achieve the impossible"