*BSD News Article 84857


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From: Rainer Busch <busch@rahul.net>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Alias on ethernet interface
Date: 12 Dec 1996 10:09:25 GMT
Organization: a2i network
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This is one for the  networking experts:

we are changing our provider. Now I want to be able to receive e-mail etc.
for some time at the new as well as the old internet address.  Both lines 
and routers are active.
Now I changed the address of ed0 to the new address, and aliased the old:

ifconfig ed0 addr.in.new.addrspace netmask 0xfffffff0
ifconfig ed0 addr.in.old.addrspace netmask 0xfffffff0

Both addresses can be pinged from in- and outside now.

This works fine so far for some time. But then - I guess some  dynamic  
routing kicks in -  ed0 kinda "forgets" its primary, and flips over to 
the other (aliased) one. This conflicts with the default route, of course, 
and - bang - the machine is off-net.

Any suggestions to resolve this cleanly ?

Rainer