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Webcast-Catalyst9k
New Member

Router is redistributing iBGP into OSPF

Hi,

I hope somebody can shed some light on this issue.

The Cisco documentation says that iBGP routes are not redistributed into IGPs such as OSPF unless it is configured using the "bgp redistribute-internal" command.

Yet, my routers are doing it without this command.

Here is an example output of "show ip route" for one of these redistributed routes:

Routing entry for 10.1.128.4/32

Known via "bgp 64712", distance 200, metric 0

Tag 13979, type internal

Redistributing via ospf 1

Last update from 163.243.66.89 00:00:00 ago

Routing Descriptor Blocks:

* 163.243.66.89, from 10.100.253.20, 00:00:00 ago

Route metric is 0, traffic share count is 1

AS Hops 3

Route tag 13979

It shows the type as "internal" and the AS is matching it's own.

What am I missing ?

Thanks,

Dirk

3 REPLIES
Cisco Employee

Re: Router is redistributing iBGP into OSPF

The "bgp redistribute-internal" is indeed a must if you want iBGP learnt route to be redistributed to another protocol.

The output you provided doesn't mean that this route is necesseraly redistributed into ospf. Just do a "show ip ospf da ext 10.1.128.4" and you will se the route is not in the ospf link state database.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: Router is redistributing iBGP into OSPF

Thanks hritter,

so the output "Redistributing via ospf 1" is not validated for this specific route ? It is merely pointing out that redistribution from BGP 64712 into OSPF 1 is turned on?

Dirk

Cisco Employee

Re: Router is redistributing iBGP into OSPF

Correct. The output "Redistributing via ospf 1" just means that bgp routes are being redistributed into ospf. So even if the specific route is filtered while redistributing from bgp to ospf, the "show ip route" for this prefix will still show "Redistributing via ospf 1".

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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