Dell MX5108n OS10 Enterprise Edition User Guide for PowerEdge MX IO Modules Re - Page 274

After the connection is established, the router sends and receives keepalive, update, and notification messages to and from its peer. Peer templates Peer templates allow BGP neighbors to inherit the same outbound policies. Instead of manually configuring each neighbor with the same policy, you can create a peer group with a shared policy that applies to individual peers. A peer template provides efficient update calculation with simplified configuration. Peer templates also aid in convergence speed. When a BGP process sends the same information to many peers, a long output queue may be set up to distribute the information. For peers that are members of a peer template, the information is sent to one place then passed on to the peers within the template. Route reflectors Route reflectors (RRs) reorganize the IBGP core into a hierarchy and allow route advertisement rules. Route reflection divides IBGP peers into two groups - client peers and nonclient peers. • If a route is received from a nonclient peer, it reflects the route to all client peers • If a route is received from a client peer, it reflects the route to all nonclient and client peers An RR and its client peers form a route reflection cluster. BGP speakers announce only the best route for a given prefix. RR rules apply after the router makes its best path decision. NOTE: Do not use RRs in forwarding paths - hierarchal RRs that maintain forwarding plane RRs could create route loops. Routers B, C, D, E, and G are members of the same AS-AS100. These routers are also in the same route reflection cluster, where Router D is the route reflector. Routers E and G are client peers of Router D, and Routers B and C and nonclient peers of Router D. 1 Router B receives an advertisement from Router A through EBGP. Because the route is learned through EBGP, Router B advertises it to all its IBGP peers - Routers C and D. 2 Router C receives the advertisement but does not advertise it to any peer because its only other peer is Router D (an IBGP peer) and Router D has already learned it through IBGP from Router B. 3 Router D does not advertise the route to Router C because Router C is a nonclient peer. The route advertisement came from Router B which is also a nonclient peer. 4 Router D does reflect the advertisement to Routers E and G because they are client peers of Router D. 5 Routers E and G advertise this IBGP learned route to their EBGP peers - Routers F and H. Multiprotocol BGP Multiprotocol BGP (MBGP) is an extension to BGP that supports multiple address families-IPv4 and IPv6. MBGP carries multiple sets of unicast and multicast routes depending on the address family. You can enable the MBGP feature on a per router, per template, and/or a per peer basis. The default is the IPv4 unicast routes. 274 Layer 3