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New Member

eigrp

I have just set up eigrp on my router, with a 10/8 for the primary eth0 address, and a 172.19.1.0/24 for the sec address of the interface, I have advertised these in eigrp but my other router doesnt seem to be picking up the secondary address ? does anyone know what this is ?

cheers

9 REPLIES
New Member

Re: eigrp

Eigrp can't pick up the secondary address until you configure redistribute connect.

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080093f09.shtml

You can try

router eigrp 100

redistribute connect

Please hope this help and rate this post.

New Member

Re: eigrp

I have tried this and the other router is still not picking it up ? any ideas

Purple

Re: eigrp

Carl,

That is probably happening due to EIGRP split-horizon. Try the following:

- redistributed connected routes under your EIGRP process

- disable split horizon on the interface to the other router: no ip split-horizon eigrp

Hope that helps - pls do remember to rate posts that help.

Paresh

New Member

Re: eigrp

please send us :

show ip route, show run and show ip eigrp topology of these routers.

Regards

New Member

Re: eigrp

which router do I need to do this on ? the one thats reciveing the updates ? and what is that doing exactly ?

thanks

Hall of Fame Super Silver

Re: eigrp

It is not true that EIGRP can not pick up secondary addresses. EIGRP does process and advertise secondary addresses assuming that the router config uses the same subnet as the primary address on all routers on that segment.

The link that was posted discusses the problem that happens if the routers do not use the same subnet as primary on their interfaces. In that situation the routers do not become neighbors and do not learn any routes from each other - not just the secondary address. It is a misunderstanding of the article to interpret that EIGRP can not process secondary addresses.

HTH

Rick

New Member

Re: eigrp

Both routers have the primary address on the same subnet !! only one has a sec on the 172.x.x.x address !!

Purple

Re: eigrp

Carl,

Try the config I suggested on the router with the secondary address.

Hope that helps - pls do remember to rate posts that help.

Paresh

Hall of Fame Super Silver

Re: eigrp

Carl has not provided much information about the topology and the specifics of what he configured. But as I re-read his posts I believe that he has two routers on a common LAN segment, that one of the routers has configured a secondary address on the LAN interface, and that the other router on the LAN segment is not learning the route of the secondary address. If that guess is correct, then Paresh is exactly correct that it is an issue with split horizon. EIGRP enforces split horizon by default (part of its legacy growing out of IGRP) and will not advertise the network/subnet of the secondary interface out that same interface. If Carl does disable split horizon then EIGRP would advertise the network/subnet of the secondary out that same interface.

As a side note: it is best practice with secondary addressing to configure the secondary addresses on all the routers with interfaces on that segment rather than just configuring it on one router.

HTH

Rick

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