Summary of BGP Configuration Tasks

Configuring Basic BGP Functions

On BGP networks, unauthorized users can attack the BGP network by modifying data packets or forging authorized users. To ensure security of services carried on BGP networks, configure BGP MD5 authentication, BGP keychain authentication, or Generalized TTL Security Mechanism (GTSM) function.

Configuring BGP Security

Because routes received from an IBGP peer will not be sent to other IBGP peers, fully-meshed connections must be established on the IBGP network. However, when there are many devices, peer configuration is very complex on the fully-meshed IBGP network, and the consumption of network resources and device CPU resources will increase. To reduce the number of IBGP network connections and better plan the network, configure the route reflector and confederation.

Simplifying IBGP Network Connections

In a BGP routing table, there may be multiple routes to the same destination. To guide route selection, BGP defines next-hop policies and route selection rules. The priority of next-hop policies is higher than that of BGP route selection rules. After the next-hop policies are performed, BGP selects routes according to the route selection rules.

Usually there are multiple valid routes to the same destination on the network. If BGP only advertises the optimal route to its peer, unbalanced traffic on different routes will occur. The BGP load-balancing configuration can balance load on different routes and reduce network congestion.

Configuring BGP Route Selection and Load Balancing

With the expansion of the network scale, the sharp increase of routing tables leads to greater load on networks and increasing network security problems. To solve this problem, filter routes according to the routing policies and only send and receive required BGP routes. In addition, multiple routes to the same destination may exist. If these routes need to pass through different ASs, direct service traffic to specific ASs or filter the routes to be advertised.

Controlling the Receiving and Advertisement of BGP Routes

To enable BGP to rapidly detect network changes, speed up the BGP network convergence. To minimize the effect on networks from route flapping and reduce load on the device, slow down the BGP network convergence.

Adjusting the BGP Network Convergence Speed

To avoid long service interruption when faults occur on BGP networks, adopt the solution of standby link. However, the BGP mechanism requires more than 1 second to detect the faults and perform an active/standby switchover. To ensure that users of delay-sensitive services such as the voice service do not detect the service interruption, associate BGP tracking, BGP, and BFD to implement fast fault detection, and use BGP GR to perform a fast switchover after the fault detection.

Configuring BGP Reliability

The BGP routing table on a medium or large BGP network contains a large number of routing entries. Storing the routing table consumes a lot of memory, and transmitting and processing the routing information consumes a lot of network resources. Route summarization can reduce the size of a routing table, prevent specific routes from being advertised, and minimize the impact of route flapping on networks. Although BGP automatic route summarization is easy to configure, it only summarizes routes according to the natural network segment. BGP manual route summarization can be used with flexible routing policies to enable BGP to effectively transmit and control routes.

Configuring BGP Route Summarization

The BGP routing table on a medium or large BGP network contains a large number of routing entries. Storing the routing table consumes a large number of memory resources, and transmitting and processing the routing information consumes a large number of network resources. If multiple routes in a peer BGP routing table are sent only from a local device, configure the local device to send a default route to its peer. In this case, the local device will send a default route with the next-hop address as the local address to its peer, regardless of whether there is a default route in the local routing table. After the local device is configured to send only the default route to its peer using the routing policies, the number of network routes is greatly reduced and the peer and network memory resources are greatly saved.

Configuring BGP to Advertise Default Routes to Peers

Traditional BGP-4 only manages IPv4 unicast routing information and does not support route transmission between ASs of other networks such as multicast networks. To support multiple types of network layer protocols, the Internet Engineering Task Force (IETF) extends BGP-4 to Multiprotocol Extensions for BGP-4 (MP-BGP) defined in RFC 4760. MP-BGP is called Multicast BGP (MBGP) on multicast networks.

Configuring MP-BGP