From: Howard C. Berkowitz (hcb@xxxxxxxxxxxx)
Date: Sun Feb 24 2002 - 14:32:41 GMT-3
At 6:43 PM +0200 2/24/02, Shadi wrote:
>Hi,
>
>
>I have been working with BGP lately, and I noticed that the default
>information originate does not inject the default route 0.0.0.0 inside the bgp
>table? even syncronization is disabled!!
That's exactly how it's supposed to work. You're not creating a
default route for the BGP-speaking router; you're telling it to
announce default to peers. In real-world Internet operations, the
possibility of widely distributed default routes has enormous risk
for loop formation.
>
>but it did work when I redistribute default route 0.0.0.0 into bgp with this
>command?
Note that when you do default information originate, the default
route does NOT appear in your main routing table. Again, the DIO
default is not meant for the local router. Default route _is_ meant
for the local router, so it's reasonable that it would redistribute
into the RIB and loc-RIB.
Quick summary:
ip route 0.0.0.0 0.0.0.0 <next hop | interface> ! equivalent default router
Eligible for use in the local RIB. Can be redistributed as a static route.
default gateway: for use on non-routing devices to find their default router
Irrelevant about routing table, because there won't be any when this
is needed
default network: mostly an IGRP concept.
default information originate: generated on your router but not used by it;
intended for OTHER routers. Without ALWAYS keyword, the default will be
advertised if and only if your local router has a default route. With
ALWAYS, the local router will always propagate default.
-- "What Problem are you trying to solve?" ***send Cisco questions to the list, so all can benefit -- not directly to me*** ******************************************************************************* * Howard C. Berkowitz hcb@gettcomm.com Chief Technology Officer, GettLab/Gett Communications Technical Director, CertificationZone.com "retired" Certified Cisco Systems Instructor (CID) #93005
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