default-information originate

mohammedmahmoud · ‎01-13-2007

Hi All,

I understand that for a routing protocols to advertise a default route to its neighbors using the "default-information originate" command, ISIS, EIGRP, OSPF (unless using the always keyword) and BGP (requiring further redistribution) needs a default route to already exist in the routing table before advertising a default route through that command, can any one confirm whether RIP requires valid default route in the routing table before originating the default route using this command or not ?

Thanks in advance,

Mohammed Mahmoud.

Harold Ritter · ‎01-13-2007

When used with RIP, the "default-information originate" will generate the default route whether it is present in the RIB or not.

You need to use a route-map if you wish to conditionally generate the default route.

Hope this helps,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
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Cisco México
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mohammedmahmoud · ‎01-13-2007

Hi Harold,

Thanks alot, what about IGRP and EIGRP ?

Edison Ortiz · ‎01-13-2007

Mohammed,

EIGRP does not provide conditional advertisement features such as RIP, OSPF or BGP. EIGRP does not advertise its default route by using default information originate.

With EIGRP you need to create a default route or an interface summary route, for instance

router eigrp 10

redistribute static

ip route 0.0.0.0 0.0.0.0 null0

or

interface s0/0

ip summary-address eigrp 10 0.0.0.0 0.0.0.0

HTH,

mohammedmahmoud · ‎01-14-2007

Hey there,

I've confirmed what you've said but with only one thing to add; Normally, exterior/default routes are always accepted and default information is passed between EIGRP processes when redistribution occurs. when doing so, we still need to confirm the following command to either allow the sending or receiving of a default route (should be there by default):

Router(config-router)#default-information ?

allowed Allow default information

in Accept default routing information

out Output default routing information

Note: The default network of 0.0.0.0 used by Routing Information Protocol (RIP) cannot be redistributed by IGRP but can be redistributed by EIGRP.

Thanks very much.