OS10 Enterprise Edition User Guide Release 10.4.0E(R3)

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Confederations

Another way to organize routers within an AS and reduce the mesh for IBGP peers is to configure BGP confederations. As with route reflectors, Dell EMC recommends BGP confederations only for IBGP peering involving many IBGP peering sessions per router.

When you configure BGP confederations, you break the AS into smaller sub-ASs. To devices outside your network, the confederations appear as one AS. Within the confederation sub-AS, the IBGP neighbors are fully meshed and the MED, NEXT_HOP, and LOCAL_PREF attributes maintain between confederations.

  1. Enter the confederation ID AS number in ROUTER-BGP mode (1 to 65535 for 2–byte, 1 to 4294967295 for 4–byte).
    confederation identifier 
                                           as-number
                                        
  2. Enter which confederation sub-AS are peers in ROUTER-BGP mode, from 1 to 65535 for 2–byte, 1 to 4294967295 for 4–byte. All Confederation routers must be either 4 bytes or 2 bytes. You cannot have a mix of router ASN support.
    confederation peers 
                                           as-number [... as-number]
                                        

Configure BGP confederations

OS10(config)# router bgp 65501
                                 OS10(conf-router-bgp-65501)# confederation identifier 100
                                 OS10(conf-router-bgp-65501)# confederation peers 65502 65503 65504
                                 OS10(conf-router-bgp-65501)# neighbor 1.1.1.2
                                 OS10(conf-router-neighbor)# remote-as 65502
                                 OS10(conf-router-neighbor)# no shutdown
                                 OS10(conf-router-neighbor)# exit
                                 OS10(conf-router-bgp-65501)# neighbor 2.1.1.2
                                 OS10(conf-router-neighbor)# remote-as 65503
                                 OS10(conf-router-neighbor)# no shutdown
                                 OS10(conf-router-neighbor)# exit
                                 OS10(conf-router-bgp-65501)# neighbor 3.1.1.2
                                 OS10(conf-router-neighbor)# remote-as 65504
                                 OS10(conf-router-neighbor)# no shutdown
                                 OS10(conf-router-neighbor)# exit
                                 OS10(conf-router-bgp-65501)# end
                                 OS10# show running-configuration bgp
                                 !
                                 router bgp 65501
                                 confederation identifier 100
                                 confederation peers 65502 65503 65504
                                 !
                                 neighbor 1.1.1.2
                                 remote-as 65502
                                 no shutdown
                                 !
                                 neighbor 2.1.1.2
                                 remote-as 65503
                                 no shutdown
                                 !
                                 neighbor 3.1.1.2
                                 remote-as 65504
                                 no shutdown
                              

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