[quagga-dev 3680] Re: BGP distribution into OSPF / next-hop is dropped?

Hasso Tepper hasso at estpak.ee
Sat Sep 24 15:25:29 BST 2005


Joe Rhett wrote:
> I've noticed that when redistributing BGP routes into OSPF, the next-hop
> attribute is dropped instead of advertised with the link state.  Is this
> the expected or desired behavior?
> 
> Example
> 
> R1 <------> R2 <-----> R3
> 
> R1 and R3 are ebgp-multihop peers.  R3 advertises a route to R1, with
> next-hop set to itself.  R1 redistributes the route into OSPF, however the
> adv-router for that route in OSPF is R1's address, so a routing loop
> occurs.

Advertising router is to specify router-id of OSPF router which originates
route into OSPF domain. From RFC2328 (12.1.5):

"This field specifies the OSPF Router ID of the LSA's originator."

> Shouldn't the BGP next-hop attribute be mapped into the OSPF advertisement?
> OSPF can handle this information just fine...
 
I'm not aware of any standard behaviours which could handle this (IMHO
stupid) situation. In theory you can handle this situation with tags
though.


regards,

-- 
Hasso Tepper
Elion Enterprises Ltd.
WAN administrator



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