Exam 642-883 topic 1 question 137 discussion

Loop Prevention in Route Reflectors Removing the full mesh requirements in an IBGP topology introduces the potential for routing loops. When RFC 1966 was drafted, two other BGP route reflector specific attributes were added to prevent loops. ORIGINATOR_ID, an optional nontransitive BGP attribute is created by the first route reflector and sets the value to the RID of the router that injected/advertised the route into the AS. If the ORIGINATOR_ID is already populated on an NLRI, it should not be overwritten. If a router receives a NLRI with its RID in the Originator attribute, the NLRI is discarded. CLUSTER_LIST, a nontransitive BGP attribute, is updated by the route reflector. This attribute is appended (not overwritten) by the route reflector with its cluster-id. By default this is the BGP identifier. The cluster-id can be set with the BGP configuration command bgp cluster-id cluster-id on IOS and IOS XR nodes. NX-OS devices use the command cluster-id cluster-id.

Loop Prevention in Route Reflectors Removing the full mesh requirements in an IBGP topology introduces the potential for routing loops. When RFC 1966 was drafted, two other BGP route reflector specific attributes were added to prevent loops. ORIGINATOR_ID, an optional nontransitive BGP attribute is created by the first route reflector and sets the value to the RID of the router that injected/advertised the route into the AS. If the ORIGINATOR_ID is already populated on an NLRI, it should not be overwritten. If a router receives a NLRI with its RID in the Originator attribute, the NLRI is discarded. CLUSTER_LIST, a nontransitive BGP attribute, is updated by the route reflector. This attribute is appended (not overwritten) by the route reflector with its cluster-id. By default this is the BGP identifier. The cluster-id can be set with the BGP configuration command bgp cluster-id cluster-id on IOS and IOS XR nodes. NX-OS devices use the command cluster-id cluster-id.