The MPLS-OPS Archive

[Rajiv Asati <rajiva@cisco.com>]

Ali,

> When PE3 needs to send packets to the
> corresponding address, how would PE3 choose between the two PEs: PE1 and
> PE2. i.e, how would PE3 chosse between the 2 LSPs, LSP1 and
> LSP2.

This has to be done at the BGP level, since VPNv4 prefixes are exchanged
among the PE routers via MP-BGP.

So, PE3 would need to be enabled with BGP multipath for that VPN
customer.
This CLI might vary from the vendor to vendor, but one vendor I am the
most familiar with would require the BGP VRF address-family
(address-family ipv4 vrf <vrf_name>) at PE3 to be configured with
multipath (maximum-path ibgp 2).

Hope this helps.

Cheers,
Rajiv


At 12:52 PM 10/18/2004, Ali wrote:
>  
> I appreciate your help on the following topic. a CEa is dual homed to 2
> PEs. How PE3 chooses among PE1 and PE2 to send packets to addresses on
> CEa.
>                    
> ________________________________
>                    
> |                                                      
> |
>                    
> |                                                      
> |
> CEa -----------
> PE1                                                 
> PE3
>  
> |                                                                        
> |
>  
> |                                     
> MPLS NETWORK         |
>  
> -----------------PE2                                                  
> |
>                     
> |                                                      
> |
>                     
> |                                                      
> |
>                     
> --------------------------------------------------------
>  
> CEa is dual-Homed on PE1 and PE2. 
> CEa advertises the route for prefix 10.1/16 (to PE1 and PE2) 
> PE1 and PE2 install a local route to 10.1/16 in their VRF.
>  
> PE1 advertises the route for 10.1/6 to PE3, and
> PE2 does the same
>  
> PE3 establishes 2 LSPs: LSP1:  PE3 to PE1   and 
> LSP2: PE3 to PE2
>  
> When PE3 needs to send packets to the corresponding address, how would
> PE3 choose between the two PEs: PE1 and PE2. i.e, how would PE3 chosse
> between the 2 LSPs, LSP1 and LSP2.
>  
> Thank you.
> Allal.
>
>
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