KB.15.15

Route refresh

When the inbound policy-filter for a peer changes, the routes advertised by the peer must be

presented to the policy-filter engine to take effect. This means that all the routes that were received

from a peer will have to be preserved in the router and this would raise the demand on memory

and CPU resources of the router. The route refresh capability allows the router to request the peer

to re-advertise the routes thereby avoiding the requirement to keep a copy of all the routes that

were received from all the peers.

BGP basic configuration

The following configuration tasks are described as required or optional.

RemarksTask

RequiredConfiguring BGP connection

OptionalConfiguring BGP route redistributionControlling route distribution and

reception

OptionalConfiguring BGP route distribution

filtering policies

OptionalConfiguring BGP route reception

filtering policies

OptionalRoutemap filtering and route

modifications

OptionalConfiguring BGP route attributes

OptionalTuning and optimizing BGP networks

OptionalConfiguring BGP community

OptionalConfiguring BGP GR

Configuring a BGP connection

NOTE: Since BGP runs on TCP, you must specify the IP addresses of the peers in order to establish

a BGP session. The peers may not be directly connected.

IP addresses of loopback interfaces can be used to improve the stability of BGP connections.

Prerequisites

The neighboring nodes must be accessible to each other at the network layer.

Creating a BGP connection

• A router ID is the unique identifier of a BGP router in an AS.

• To ensure the uniqueness of a router ID and enhance network reliability, you can specify in

BGP configuration context the IP address of a local loopback interface as the router ID.

• If no router ID is specified in BGP context, the global router ID is used.

• If the global router ID is used and then it is removed, the system will select a new router ID.

• Unconfiguring the router ID in BGP context can make the system select a new router ID.

310 Border Gateway Protocol (BGP)