Dynamic Update Peer-Groups
Currently, the rapid growth in the size of the routing table and the complexity of the network topology require BGP to support more peers. Especially in the case of a large number of peers and routes, high-performance grouping and forwarding are required when a router needs to send routes to a large number of BGP peers, most of which share the same outbound policies.
The dynamic update peer-groups feature treats all the BGP peers with the same outbound policies as an update-group. In this case, routes are grouped uniformly and then sent separately. That is, each route to be sent is grouped once and then sent to all peers in the update-group, improving grouping efficiency exponentially. For example, a route reflector (RR) has 100 clients and needs to reflect 100,000 routes to these clients. If the RR sends the routes grouped per peer to 100 clients, the total number of times that all routes are grouped is 10,000,000 (100,000 x 100). After the dynamic update peer-groups feature is used, the total number of grouping times changes to 100,000 (100,000 x 1), improving grouping performance by a factor of 100.
Applications
BGP uses the dynamic update peer-groups technology when a large number of peers and routes exist and most peers share the same outbound policies, improving BGP route grouping and forwarding performance. The dynamic update peer-groups feature applies to the following scenarios:
International gateway
As shown in Figure 1, the Internet gateway (IGW) router sends routes to all neighboring ASs. If the IGW router supports the dynamic update peer-groups feature, its BGP route forwarding performance will be greatly improved.
RR
As shown in Figure 2, RRs send routes to all clients. If the RRs support the dynamic update peer-groups feature, their BGP route forwarding performance will be greatly improved.
ASBR
As shown in Figure 3, RouterB, as an Autonomous System Boundary Router (ASBR), sends all the routes received from an EBGP neighbor RouterA to all IBGP neighbors. If RouterB supports the dynamic update peer-groups feature, its BGP route forwarding performance will be greatly improved.
