![]() ![]() When there are Route Reflectors implemented in the network, are route learned from a client is advertised to clients but with the Originator ID attrib set. considering that iBGP peers could be physically one hop away, or many hops away, as long as there is reachablity between them, to implement the same concept as spilt horizon to prevent loops in BGP, its became a rule not to re-advertise a route learned from a peer within an Autonomous System (iBGP peers) to other peers.īecause from an Administrative point of view, it is assumed that all the iBGP peers are aware of eachother and have full connectivity, unless they are set to be RR clients. In the case of eBGP networks, the route-reflector function is absent or nonexistent. With this updated design, the logical and. To resolve the routing loop in this example, CE-A1 and PE-M1 should be RR clients of only PE-T1, and CE-A2 and PE-M2 should be RR clients of only PE-T2. This practice helps prevent routing loops. We will end with a short lab demonstrating some of the items that were presented during the session. For EBGP-learned routes, the BGP speaker is the only source of routes for its AS. IBGP routes that are propagated into IBGP. ![]() Remember, BGP is rather a TCP Application to propagate prefixes over large scale networks, not an actual routing protocol. BGP route reflectors are limited to providing their services to iBGP-based peering. In BGP designs with route reflectors, the logical iBGP sessions really should follow the physical topology. Topics of our session include BGP General Operation, Attributes and Policy Control, BGP Path Selection Algorithm, Applying Policy with BGP, BGP Route-Reflectors, Multi- protocol BGP and some common BGP Deployment Scenarios. When deciding how a route reflector that is also an ASBR should propagate EBGP routes into IBGP, the key observation is that RFC4456 deals only with 'reflected' routes, i.e. Remember about the old time split horizon rule? "not to advertise a route from the same interface that you received it from" well, it was for IGP protocols. ![]()
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