Configuring The Way To Advertise/Receive Routing Information; Importing Routes - H3C S7500 Series Operation Manual

Operation Manual – Routing Protocol
H3C S7500 Series Ethernet Switches
Caution:
A router must be assigned a router ID in order to run BGP protocol. A router ID is a
32-bit unsigned integer. It uniquely identifies a router in an AS.
A router ID can be configured manually. If no router ID is configured, the system
will automatically select an IP address from the IP addresses of the interfaces as
the router ID. A router ID is selected in the following way: if loopback interface
addresses are configured, the system chooses the latest configured IP address as
the router ID; if no loopback interface is configured, the first configured IP address
among the IP addresses of other interfaces will be the router ID. For network
reliability consideration, you are recommended to configure the IP address of a
loopback interface as the router ID.
Router IDs can be re-selected. A re-selected router ID takes effect only after the
BGP process is restarted.
In order for route update packets to be sent even if problems occur on interfaces,
you can configure the source interfaces of route update packets as a loopback
interface.
Normally, EBGP peers are connected through directly connected physical links. If
no such link exists, you need to use the peer ebgp-max-hop command to allow
the peers to establish multiple-hop TCP connections between them.
6.4 Configuring the Way to Advertise/Receive Routing
Information
6.4.1 Configuration Prerequisites
Make sure the following operation is performed before configuring the way to
advertise/receive BGP routing information.
Enabling the basic BGP functions
Make sure the following information is available when you configure the way to
advertise/receive BGP routing information.
The aggregation mode and the aggregated route
Access list number
Filtering direction (advertising/receiving) and the route policies to be adopted.
Route dampening settings, such as half-life and the thresholds.

6.4.2 Importing Routes

With BGP employed, an AS can send its interior routing information to its neighbor
ASs. However, the interior routing information is not generated by BGP; it is obtained
6-9
Chapter 6 BGP Configuration