eBGP routes not getting advertised to iBGP peers.

[rahul nair]

Hi ,

I have a strange situation. 

I have a few routers in an iBGP domain which are direct neighbors with each other. 

Two of those routers  ( RT2 and RT6 ) also learn some routers through an eBGP peer on the WAN link .

These eBGP learnt routes are not advertised to the iBGP peers . 

What could be the reason for this ?

For eg : 

In the below output RT6 clearly has an eBGP route for 10.0.0.0. apart from the iBGP route. 

So ideally this route should be passed on to the iBgp peers of RT6  ?

RT6

 r>i 10.0.0.0 10.137.67.1 0 100 0 65000 64601 64600 ?
r                   10.237.255.50 100 0 65209 65210 65000 64601 64600 ?
 

But when i look into the iBGP peer RT2, i cant see the route through "10.237.255.50" passed on to RT2.

For eg : This is how the routes look like in RT2. 

r 10.0.0.0 10.137.64.2 100 0 65201 65000 64601 64600 ?
r>i            10.137.67.1  0 100 0 65000 64601 64600 ?

what could be the reason for this ? 

Thanks,

Rahul Nair.

[Harold Ritter · Accepted solution]

Hi Rahul,

BGP only advertise the best path. On RT6, the path learnt from 10.237.255.50 is not the best path, hence it not being advertised to RT2.

Regards,

[rahul nair]

Thanks Harold.
I missed that detail :)

Thanks,
Rahul Nair.