From: Dan (dp595@xxxxxxxxxxxxx)
Date: Wed Apr 17 2002 - 15:08:27 GMT-3
Let me clarify. I should have said secondary networks don't support
broadcast/multicast "routing" on them. This is because routing updates are
always sourced with the primary ip address. If you have the following:
interface Serial0
ip address 1.1.1.1/24
ip address 2.2.2.2/24 secondary
All [broadcast/multicast] routing advertisements sent out on that interface
will be sourced with 1.1.1.1 if my memory serves correctly, therefore any
receiving routers not on the 1.1.1.0/24 network will reject those routing
updates. It doesn't matter if you have specified a "network" statement for
both networks under your routing process. All updates are sourced with
1.1.1.1. Configuring unicast routing avoids this pitfall.
Dan
> Secondary networks do not support multicast/broadcast traffic last time I
> checked, therefore you'll need to use a workaround here.
> Another method instead of the tunnel is to configure unicast "neighbors"
for
> your routing protocol.
>
> Dan Pontrelli
> CCIE# 8040
>
>
>
> > Am I the only person have troubles with the secondary address? I have
> > the following (everything is in 172.16.x.x/16):
> >
> > 24.1/24----\
> > R2--2.2/24-ospf-2.1/24--R6--1.1/28-igrp-1.2/28--R3--3.1/28
> > 28.1/28----/
> >
> > When I add the 2nd address 36.1/24 and 36.2/24 on r6 and r3, 24.1/24 is
> > not seen in 'debug ip igrp trans'. When I switched the primary with
> > the secondary addresses, i.e. /28 is secondary address and /24
> > is primary address, only /24 routes can be seen in the debug. It looks
> > like routes can only be distributed via primary interface.
> >
> > The problem was fixed by using the tunnel interface. But I'm wondering
> > if you have seen this problems. I've checked the archives and someone
> > said the secondary addresses would stop working if you reboot the
> > router. I've used it in the past without any problems, but wondering
> > if this is a bad choice.
> >
> > Thanks,
> > Chang
> >
> >
> >
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