Re: Preferred router in an iBGP setup and load-balancing btw the iBGPs

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Jun 3rd, 2009
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Hi,


1) My question is that if there is an iBGP peering between two routers in an ASN (for redundancy purposes),

which router would be the active router to send/receive routes ? Would be the router with the highest router-id ?


2) Now if this pair of routers are peering with CE routers in a VPN in strict mode, can I send traffic on one link and

receive traffic on the other link ? Just need to double confirm this fact.


VPN (strict mode) ISP CE1 -- iBGP R1


VPN (strict mode) ISP CE2 -- iBGP R2


Thank you,


Cheers,

- InternetB -

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Laurent Aubert Wed, 06/03/2009 - 06:21
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  • Cisco Employee,

Hi,


1) There is no active role between two iBGP peers. Any BGP router can send and receive updates following some rules.


2) Do you have an eBGP session between Rx and CEx ? not sure to understand what VPN strict mode means.


You can play with BGP attributes to influence your exit point and the return path. But to influence the return path, it depends if you manage the CE or not because if not, they may not take into consideration the attributes you sent.


HTH


Laurent.

InternetB Wed, 06/03/2009 - 17:50
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Hi,

1) So would this means that if no attributes are set on the iBGP router, ie)the incoming routes would come in based on the BGP selection process, AS Path/MED ?


2) Yes, its an eBGP sessesion between Rx and Cx.

The definition for strict mode is as follows :-

Strict Mode --   Examines incoming packets to determine whether the source address is in the Forwarding Information Base (FIB) and permits the packet only if the source is reachable.


3) I am not managing the CE router. The SP uses Local Pref,AS_Path, MED for me to manipulate route selection.


Thank you,


Cheers,

- InternetB -

Laurent Aubert Thu, 06/04/2009 - 06:29
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  • Cisco Employee,

Hi,


I need to step back. Can you explain what you want to do in terms of routing policy ?


Thanks


Laurent.

InternetB Thu, 06/04/2009 - 20:04
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Hi,

This is just a theoretical question. I am working on a design and trying to see how to manipulate the BGP attributes and the setup is as explained earlier.


Thank you,


Cheers,

- InternetB -

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