Dell Force10 S4820T S4820T Configuration Guide - Page 184

www.dell.com | support.dell.com { • If a route was received from a nonclient peer, reflect the route to all client peers. • If the route was received from a client peer, reflect the route to all nonclient and all client peers. To illustrate how these rules affect routing, refer to the illustration below and the following steps.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. Router E and H are client peers of Router D; Routers B and C and nonclient peers of Router D. eBGP Route Router A Router B { { iBGP Routes eBGP Route Router E Router F iBGP Route Route Reflector Router D Route Reflector Client Peers Router C iBGP Routes Router G Router H eBGP Route 1. Router B receives an advertisement from Router A through eBGP. Since 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 and the route advertisement came from Router B who is also a non-client 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 then advertise this iBGP learned route to their eBGP peers Routers F and H. Confederations Communities BGP communities are sets of routes with one or more common attributes. This is a way to assign common attributes to multiple routes at the same time. 184 | Border Gateway Protocol IPv4 (BGPv4)