Specifying the source address of TCP connections
By default, BGP uses the primary IPv4/IPv6 address of the output interface in the optimal route to a peer or peer group as the source address of TCP connections to the peer or peer group. You can change the source address in the following scenarios:
If the peer's IPv4/IPv6 address belongs to an interface indirectly connected to the local router, specify that interface as the source interface for TCP connections on the peer. For example, interface A on the local end is directly connected to interface B on the peer. If you use the peer x.x.x.x as-number as-number command on the local end, and x.x.x.x is not the IPv4 address of interface B, you must do the following:
Use the peer connect-interface command on the peer.
Specify the interface whose IPv4 address is x.x.x.x as the source interface.
If the source interface fails on a BGP router that has multiple links to a peer, BGP must re-establish TCP connections. To avoid this problem, use a loopback interface as the source interface or use the IP address of a loopback interface as the source address.
If the BGP sessions use the IP addresses of different interfaces, specify a source address or source interface for each peer to establish multiple BGP sessions to a router. Specify a source address for each peer if the BGP sessions use the different addresses of the same interface. Otherwise, the local BGP router might fail to establish a TCP connection to a peer when it uses the optimal route to determine the source address.
To specify the source address of TCP connections (IPv4 unicast/multicast address family):
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter BGP instance view or BGP-VPN instance view. |
| N/A |
3. Specify the source address of TCP connections to a peer or peer group. | peer { group-name | ipv4-address [ mask-length ] } source-address source-ipv4-address | By default, BGP uses the primary IPv4 address of the output interface in the optimal route to a peer or peer group as the source address of TCP connections to the peer or peer group. |
4. Specify the source interface of TCP connections to a peer or peer group. | peer { group-name | ipv4-address [ mask-length ] } connect-interface interface-type interface-number |
To specify the source address of TCP connections (IPv6 unicast/multicast address family):
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter BGP instance view or BGP-VPN instance view. |
| N/A |
3. Specify the source IPv6 address of TCP connections to a peer or peer group. | peer { group-name | ipv6-address [ prefix-length ] } source-address source-ipv6-address | By default, BGP uses the IPv6 address of the output interface in the optimal route to the BGP peer or peer group as the source address of TCP connections to the peer or peer group. |
4. Specify the source interface of TCP connections to a peer or peer group. | peer { group-name | ipv6-address [ prefix-length ] } connect-interface interface-type interface-number |