My border routers obtain a default route in fact, and OSPF must redistribute this route to LAN Routers. Here is a scheme
|-------------- R1 site 1------------ R3 Site 1 | BGP AS 650XX | OSPF a3 | |-------------- R2 site 1------------ R4 Site 1 | | WAN | GRE (OSPF a3) | | |-------------- R1 site 2 ------------ R3 Site 2 | BGP AS 650YY | OSPF a3 | |-------------- R2 site 2------------- R4 Site 2 Each BGP AS redistribute a default route. you are right, OSPF should redistribute default route (it's the case) for R3/R4 routers on each site. The problem is between between the two border routers and on GRE. Please note R1 and R2 are full mesh GRE (R1S1 -> R1S2 / R1S1 -> R2S2 / R2S1 -> R2S1 -> R2S1 / R2S1 -> R2S2). When i said priority it's not route priority but protocol priority (BGP: 48/OSPF: 40) Any idea ? I think the only and the best solution is to filter installed routes -- Best regards, Loïc BLOT, UNIX systems, security and network expert http://www.unix-experience.fr Le mercredi 01 mai 2013 à 23:26 +0200, Claudio Jeker a écrit : > On Wed, May 01, 2013 at 10:00:55PM +0200, Loïc BLOT wrote: > > In fact, this isn't really an interarea problem but a inter protocol > > problem. > > > > Next month i'll have two border routers which are connecter to MAN by > > BGP. In my LAN and on my tunnels i'm in a "LAN backbone" area. > > > > Because of the priority of OSPF and the default route redistribution, > > the default route will be redistributed on my GRE tunnel and also > > between the two border routers and those routes are prior to BGP routes. > > A problem is also redistribute default is a global function, then the > > default route will be redistributed (and also taken) everywhere) . > > If we could configure redistribute default/static/connected on area, i > > could split my "LAN backbone" area into 3 areas (1 per site + 1 for > > GRE), and do not redistribute default route on GRE, but the > > redistribution between the two border routers is not fixed. Then the > > only way to resolve this issue is to filter entries to kernel routing > > table, you are right. > > > > Hmm. I don't know your network setup but you should redistribute the > default route from your border routers. Also the routing priority only > matters for equal prefixes so the more specifc bgp routes from a full feed > will still be considered. Last but not least on border routers I also > normaly install a default blackhole route which again would prevent the > ospf default route to take precedence (if the prio is set right of course). > > -- > :wq Claudio [demime 1.01d removed an attachment of type application/pgp-signature which had a name of signature.asc]
