Controlling Route Distribution And Reception - H3C S7500E Series Operation Manual

Operation Manual – IPv4 Routing
H3C S7500E Series Ethernet Switches
Note:
It is required to specify for a BGP router a router ID, a 32-bit unsigned integer and
the unique identifier of the router in the AS.
You can specify a router ID manually. If not, the system selects an IP address as the
router ID. The selection sequence is the highest IP address among loopback
interface addresses; if not available, then the highest IP address of interfaces. It is
recommended to specify a loopback interface address as the router ID to enhance
network reliability. Only when the interface with the selected Router ID or the
manual Router ID is deleted will the system select another ID for the router.
You need to create a peer group before configuring it. Refer to
Peer Groups
To establish multiple BGP connections to a BGP router, you need to specify on the
local router the respective source interfaces for establishing TCP connections to the
peers on the peering BGP router; otherwise, the local BGP router may fail to
establish TCP connections to the peers when using the outbound interfaces of the
best routes as the source interfaces.
In general, direct physical links should be available between EBGP peers. If not, you
can use the peer ebgp-max-hop command to establish a TCP connection over
multiple hops between two peers. You need not use this command for directly
connected EBGP peers, which employ loopback interfaces for peer relationship
establishment.
If you both reference a routing policy and use the peer { group-name | ip-address }
preferred-value value command to set a preferred value for routes from a peer, the
routing policy sets a non-zero preferred value for routes matching it. Other routes
not matching the routing policy uses the value set with the command. If the
preferred value in the routing policy is zero, the routes matching it will also use the
value set with the command. For information about using a routing policy to set a
preferred value, refer to the command peer { group-name | ip-address }
route-policy route-policy-name { export | import } in this document, and the
command apply preferred-value preferred-value in Routing Policy Commands of
the IP Routing Volume.

5.4 Controlling Route Distribution and Reception

5.4.1 Prerequisites
Before configuring this task, you have completed BGP basic configuration.
for creating a peer group.
5-22
Chapter 5 BGP Configuration
Configuring BGP