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Vyatta documentation

Learn how to install, configure, and operate the Vyatta Network Operating System (Vyatta NOS) and Orchestrator, which help drive our virtual networking and physical platforms portfolio.

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Configuring BGP

Confederations

Confederations allow large AS to sub-divide the AS into sub-AS. This helps solve the scalability issues associated with having to maintain a full mesh of iBGP connections between all iBGP routers in the AS. In the confederation example shown in the following figure, routers R1 and R3 are configured in one sub-AS (AS number 65031) and routers R2 and R4 are configured in a different sub-AS (AS number 65021).

Note: We assume that the routers in AS200 and AS300 are configured appropriately as eBGP peers.
Figure 1. BGP confederation

This example assumes that the configurations in previous sections have been performed.

To create the confederation shown in the preceding figure, perform the following steps in configuration mode.

Table 1. Creating a BGP confederation

Router

Step

Commands

R1

Delete current BGP configuration. 

vyatta@R1# delete protocols bgp 100

R1

To allow routes from AS200 to be injected into RIB on R3. 

vyatta@R1# set protocols bgp 65031 neighbor 10.0.0.33 nexthop-self

R1

Set R3 in the same sub-AS as R1. 

vyatta@R1# set protocols bgp 65031 neighbor 10.0.0.33 remote-as 65031

R1

Define the IP address on the local R1 router that is used to peer with the R3 router. 

vyatta@R1# set protocols bgp 65031 neighbor 10.0.0.33 update-source 10.0.0.11

R1

Set the AS200 router in a different AS than R1. 

vyatta@R1# set protocols bgp 65031 neighbor 88.88.88.2 remote-as 200

R1

Set the outbound filter. 

vyatta@R1# set protocols bgp 65031 neighbor 88.88.88.2 route-map export eBGP-EXPORT

R1

Set the inbound filter. 

vyatta@R1# set protocols bgp 65031 neighbor 88.88.88.2 route-map import eBGP-IMPORT

R1

Set the network to advertise. 

vyatta@R1# set protocols bgp 65031 address-family ipv4-unicast network 172.16.0.0/24

R1

Set the AS identifier for the confederation. 

vyatta@R1# set protocols bgp 65031 parameters confederation identifier 100

R1

Set the peer for the sub-AS. 

vyatta@R1# set protocols bgp 65031 parameters confederation peers 65021

R1

Set the router ID. 

vyatta@R1# set protocols bgp 65031 parameters router-id 10.0.0.11

R1

Commit the configuration. 

vyatta@R1# commit

R1

Display the BGP configuration. 

vyatta@R1# show protocols bgp
 65031 {
     neighbor 10.0.0.33 {
         nexthop-self
         remote-as 65031
         update-source 10.0.0.11
     }
     neighbor 88.88.88.2 {
         remote-as 200
         route-map {
             export eBGP-EXPORT
             import eBGP-IMPORT
         }
     }
     address-family ipv4-unicast {
         network 172.16.0.0/24 
         }
     }
     parameters {
         confederation {
             identifier 100
             peers 65021
         }
         router-id 10.0.0.11
     }
 }
vyatta@R1#

R2

Delete current BGP configuration. 

vyatta@R2# delete protocols bgp 100

R2

Set R3 in a different sub-AS than R2. 

vyatta@R2# set protocols bgp 65021 neighbor 10.0.0.33 remote-as 65031

R2

Define the IP address on the local R2 router that is used to peer with the R3 router. 

vyatta@R2# set protocols bgp 65021 neighbor 10.0.0.33 update-source 10.0.0.22

R2

Set R4 in the same sub-AS as R2. 

vyatta@R2# set protocols bgp 65021 neighbor 10.0.0.44 remote-as 65021

R2

Define the IP address on the local R2 router that is used to peer with the R4 router. 

vyatta@R2# set protocols bgp 65021 neighbor 10.0.0.44 update-source 10.0.0.22

R2

Activate the neighbor for the IPv4 unicast address family to enable the exchange IPv4 unicast routes. 

vyatta@R2# set protocols bgp 100 neighbor 10.0.0.44 address-family ipv4-unicast

R2

Set the network to advertise. 

vyatta@R2# set protocols bgp 65021 address-family ipv4-unicast network 172.16.0.0/24

R2

Set the AS identifier for the confederation. 

vyatta@R2# set protocols bgp 65021 parameters confederation identifier 100

R2

Set the peer for the sub-AS. 

vyatta@R2# set protocols bgp 65021 parameters confederation peers 65031

R2

Set the router ID. 

vyatta@R2# set protocols bgp 65021 parameters router-id 10.0.0.22

R2

Commit the configuration. 

vyatta@R2# commit

R2

Display the BGP configuration. 

vyatta@R2# show protocols bgp 
 65021 {
     neighbor 10.0.0.33 {
         remote-as 65031
         update-source 10.0.0.22
     }
     neighbor 10.0.0.44 {
         remote-as 65021
         update-source 10.0.0.22
     }
     neighbor 10.0.0.44 {
          address-family ipv4-unicast
     }
     address-family ipv4-unicast {
          network 172.16.0.0/24 
         }
     }
     parameters {
         confederation {
             identifier 100
             peers 65031
         }
         router-id 10.0.0.22
     }
 }
vyatta@R2#

R3

Delete current BGP configuration. 

vyatta@R3# delete protocols bgp 100

R3

Set R1 in the same sub-AS as R3. 

vyatta@R3# set protocols bgp 65031 neighbor 10.0.0.11 remote-as 65031

R3

Define the IP address on the local R3 router that is used to peer with the R1 router. 

vyatta@R3# set protocols bgp 65031 neighbor 10.0.0.11 update-source 10.0.0.33

R3

Set the R2 router in a different AS than R3. 

vyatta@R3# set protocols bgp 65031 neighbor 10.0.0.22 remote-as 65021

R3

Define the IP address on the local R3 router that is used to peer with the R2 router. 

vyatta@R3# set protocols bgp 65031 neighbor 10.0.0.22 update-source 10.0.0.33

R3

Activate the neighbor for the IPv4 unicast address family to enable the exchange IPv4 unicast routes. 

vyatta@R3# set protocols bgp 100 neighbor 10.0.0.44 address-family ipv4-unicast

R3

Set the network to advertise. 

vyatta@R3# set protocols bgp 65031 address-family ipv4-unicast network 172.16.0.0/24

R3

Set the AS identifier for the confederation. 

vyatta@R3# set protocols bgp 65031 parameters confederation identifier 100

R3

Set the peer for the sub-AS. 

vyatta@R3# set protocols bgp 65031 parameters confederation peers 65021

R3

Set the router ID. 

vyatta@R3# set protocols bgp 65031 parameters router-id 10.0.0.33

R3

Commit the configuration. 

vyatta@R3# commit

R3

Display the BGP configuration. 

vyatta@R3# show protocols bgp
  65031 {
     neighbor 10.0.0.11 {
         remote-as 65031
         update-source 10.0.0.33
     }
     neighbor 10.0.0.22 {
         remote-as 65021
         update-source 10.0.0.33
     }
     neighbor 10.0.0.44 {
          address-family ipv4-unicast
     }
     address-family ipv4-unicast {
          network 172.16.0.0/24 
          }
     }
     parameters {
         confederation {
             identifier 100
             peers 65021
         }
         router-id 10.0.0.33
     }
 }
vyatta@R3#

R4

Delete current BGP configuration. 

vyatta@R4# delete protocols bgp 100

R4

To allow routes from AS300 to be injected into RIB on R2. 

vyatta@R4# set protocols bgp 65021 neighbor 10.0.0.22 nexthop-self

R4

Set R2 in the same sub-AS as R4. 

vyatta@R4# set protocols bgp 65021 neighbor 10.0.0.22 remote-as 65021

R4

Define the IP address on the local R4 router that is used to peer with the R2 router. 

vyatta@R4# set protocols bgp 65021 neighbor 10.0.0.22 update-source 10.0.0.44

R4

Set the AS300 router in a different AS than R4. 

vyatta@R4# set protocols bgp 65021 neighbor 99.99.99.2 remote-as 300

R4

Set the outbound filter. 

vyatta@R4# set protocols bgp 65021 neighbor 99.99.99.2 route-map export eBGP-EXPORT

R4

Set the inbound filter. 

vyatta@R4# set protocols bgp 65021 neighbor 99.99.99.2 route-map import eBGP-IMPORT

R4

Activate the neighbor for the IPv4 unicast address family to enable the exchange IPv4 unicast routes. 

vyatta@R4# set protocols bgp 100 neighbor 10.0.0.44 address-family ipv4-unicast

R4

Set the network to advertise. 

vyatta@R4# set protocols bgp 65021 network 172.16.0.0/24

R4

Set the AS identifier for the confederation. 

vyatta@R4# set protocols bgp 65021 parameters confederation identifier 100

R4

Set the peer for the sub-AS. 

vyatta@R4# set protocols bgp 65021 parameters confederation peers 65031

R4

Set the router ID. 

vyatta@R4# set protocols bgp 65021 parameters router-id 10.0.0.44

R4

Commit the configuration. 

vyatta@R4# commit

R4

Display the BGP configuration. 

vyatta@R4# show protocols bgp 
 65021 {
     neighbor 10.0.0.22 {
         nexthop-self
         remote-as 65021
         update-source 10.0.0.44
     }
     neighbor 99.99.99.2 {
         remote-as 300
         route-map {
             export eBGP-EXPORT
             import eBGP-IMPORT
         }
     }
     neighbor 10.0.0.44 {
          address-family ipv4-unicast
     }
     address-family ipv4-unicast {
          network 172.16.0.0/24 
          }
     }
     parameters {
         confederation {
             identifier 100
             peers 65031
         }
         router-id 10.0.0.44
     }
 }
vyatta@R4#

Last updated: February 18, 2022