H3C Technologies H3C S12500 Series Switches - Manual (Page 227)

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Step Command Remarks
6. Configure a description for a
peer group. peer group-name description
description-text
Optional.
By default, no description is
configured for the peer group.
NOTE:
Peers added in the group can have different AS numbers.
Specifying the source interface for TCP connections
BGP uses TCP as the transport layer protocol. By default, BGP uses the output interface of the optimal
route to a peer or peer group as the source interface for establishing TCP connections to the peer or peer
group. The primary IP address of the output interface is used for establishing TCP connections. You can
specify the source interface (primary IP address) for TCP connections in the following scenarios:
• If the peer’s IP address belongs to an interface indirectly connected to the local router, you must
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. When you execute the peer
x.x.x.x as-number as-number command on the local end to specify the BGP peer, and x.x.x.x is not
the IP address of interface B, you must use the peer connect-interface command on the peer to
specify the interface whose IP address is x.x.x.x as the source interface for establishing a TCP
connection.
• If a BGP router has multiple links to a peer, and the source interface fails, BGP has to reestablish
TCP connections, causing network oscillation. To enhance stability of TCP connections, H3C
recommends that you use a loopback interface as the source interface.
• To establish multiple BGP sessions between two routers, you must specify the source interface for
establishing TCP connections to each peer on the local router; otherwise, the local BGP router might
fail to establish TCP connections to a peer when using the output interface of the best route to the
peer as the source interface.
To specify the source interface for TCP connections:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter BGP view or BGP-VPN
instance view.
• Enter BGP view:
bgp as-number
• Enter BGP-VPN instance view:
a. bgp as-number
b. ipv4-family vpn-instance
vpn-instance-name
Use either method.
3. Specify the source interface
for establishing TCP
connections to a peer or
peer group.
peer { group-name | ip-address }
connect-interface interface-type
interface-number
By default, BGP uses the output
interface of the best route to the BGP
peer or peer group as the source
interface for establishing a TCP
connection to the peer or peer
group.