The following confederation configuration example presents a confederation of three routers, each belonging to different ASs, with a single EBGP connection to a router outside of the confederation. Router 1 sees Router 2 as belonging to AS (confederation) 100. Router 2 sees Router 1 as belonging to AS 1. Within the confederation, Router 2 - 4, see each other belonging to their respective ASs: 2, 3, and 4.
BGP Confederation Example Topology displays the topology for this BGP confederation example.
Router 1
Router 1(rw)->configure Router 1(rw-config)->interface vlan 1 Router 1(rw-config-intf-vlan.0.1)->ip address 200.10.1.1 255.255.255.0 Router 1(rw-config-intf-vlan.0.1)->no shutdown Router 1(rw-config-intf-vlan.0.1)->exit Router 1(rw)->configure Router 1(rw-config)->router bgp 1 Router 1(su-config-bgp)->bgp router-id 1.1.1.1 Router 1(su-config-bgp)->neighbor 200.10.1.2 remote-as 100 Router 1(su-config-bgp)->redistribute static Router 1(su-config-bgp)->
Router 2
Router 2(rw)->configure Router 2(rw-config)->interface vlan 1 Router 2(rw-config-intf-vlan.0.1)->ip address 200.10.1.2 255.255.255.0 Router 2(rw-config-intf-vlan.0.1)->no shutdown Router 2(rw-config-intf-vlan.0.1)->exit Router 2(rw-config)->interface vlan 2 Router 2(rw-config-intf-vlan.0.2)->ip address 200.10.2.1 255.255.255.0 Router 2(rw-config-intf-vlan.0.2)->no shutdown Router 2(rw-config-intf-vlan.0.2)->exit Router 2(rw-config)->interface vlan 4 Router 2(rw-config-intf-vlan.0.4)->ip address 200.10.4.1 255.255.255.0 Router 2(rw-config-intf-vlan.0.4)->no shutdown Router 2(rw-config-intf-vlan.0.4)->exit Router 2(rw-config)->router bgp 2 Router 2(su-config-bgp)->bgp router-id 2.2.2.2 Router 2(su-config-bgp)->neighbor 200.10.1.1 remote-as 1 Router 2(su-config-bgp)->neighbor 200.10.2.2 remote-as 3 Router 2(su-config-bgp)->neighbor 200.10.4.2 remote-as 4 Router 2(su-config-bgp)->bgp confederation-id 100 Router 2(su-config-bgp)->neighbor 200.10.2.2 confed-member Router 2(su-config-bgp)->neighbor 200.10.4.2 confed-member Router 2(su-config-bgp)->redistribute static Router 2(su-config-bgp)->
Router 3
Router 3(rw)->configure Router 3(rw-config)->interface vlan 2 Router 3(rw-config-intf-vlan.0.2)->ip address 200.10.2.2 255.255.255.0 Router 3(rw-config-intf-vlan.0.2)->no shutdown Router 3(rw-config-intf-vlan.0.2)->exit Router 3(rw-config)->interface vlan 3 Router 3(rw-config-intf-vlan.0.3)->ip address 200.10.3.1 255.255.255.0 Router 3(rw-config-intf-vlan.0.3)->no shutdown Router 3(rw-config-intf-vlan.0.3)->exit Router 3(rw-config)->router bgp 3 Router 3(su-config-bgp)->bgp router-id 3.3.3.3 Router 3(su-config-bgp)->neighbor 200.10.2.1 remote-as 2 Router 3(su-config-bgp)->neighbor 200.10.3.2 remote-as 4 Router 3(su-config-bgp)->bgp confederation-id 100 Router 3(su-config-bgp)->neighbor 200.10.2.1 confed-member Router 3(su-config-bgp)->neighbor 200.10.3.2 confed-member Router 3(su-config-bgp)->redistribute static Router 3(su-config-bgp)->
Router 4
Router 4(rw)->configure Router 4(rw-config)->interface vlan 3 Router 4(rw-config-intf-vlan.0.3)->ip address 200.10.3.2 255.255.255.0 Router 4(rw-config-intf-vlan.0.3)->no shutdown Router 4(rw-config-intf-vlan.0.3)->exit Router 4(rw-config)->interface vlan 4 Router 4(rw-config-intf-vlan.0.4)->ip address 200.10.4.2 255.255.255.0 Router 4(rw-config-intf-vlan.0.4)->no shutdown Router 4(rw-config-intf-vlan.0.4)->exit Router 4(rw-config)->router bgp 4 Router 4(su-config-bgp)->bgp router-id 4.4.4.4 Router 4(su-config-bgp)->neighbor 200.10.3.1 remote-as 3 Router 4(su-config-bgp)->neighbor 200.10.4.1 remote-as 2 Router 4(su-config-bgp)->bgp confederation-id 100 Router 4(su-config-bgp)->neighbor 200.10.3.1 confed-member Router 4(su-config-bgp)->neighbor 200.10.4.1 confed-member Router 4(su-config-bgp)->redistribute static Router 4(su-config-bgp)->
Configuring BGP Confederation describes how to configure BGP confederations.
Configuring BGP Confederation
| Step | Task | Command(s) |
|---|---|---|
| 1 | In BGP configuration mode, specify the confederation this BGP router belongs to. | bgp confederation identifier confed-id |
| 2 | In BGP configuration mode, configure the specified neighbor as a member of the router's confederation. | neighbor ip-address confed-member |
| 3 | In BGP configuration mode, optionally enable the inclusion of confederation information in the AS paths sent to this router‘s peers. | neighbor {ip-address | peer-group} aggregate-confed |
| 4 | In BGP configuration mode, optionally enable BGP to drop AS-Paths with erroneous confederation segments. | bgp strict-confeds |
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