Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.112.1P1 - Page 215

NOTE: This behavior applies to all BGP neighbors. Meaning, BGP neighbors that were explicitly disabled before global shutdown also remain in disabled state. Enable these neighbors individually using the no shutdown command. Route Map Continue The BGP route map continue feature, continue [sequence-number], (in ROUTE-MAP mode) allows movement from one routemap entry to a specific route-map entry (the sequence number). If you do not specify a sequence number, the continue feature moves to the next sequence number (also known as an "implied continue"). If a match clause exists, the continue feature executes only after a successful match occurs. If there are no successful matches, continue is ignored. Match a Clause with a Continue Clause The continue feature can exist without a match clause. Without a match clause, the continue clause executes and jumps to the specified route-map entry. With a match clause and a continue clause, the match clause executes first and the continue clause next in a specified route map entry. The continue clause launches only after a successful match. The behavior is: • A successful match with a continue clause-the route map executes the set clauses and then goes to the specified route map entry after execution of the continue clause. • If the next route map entry contains a continue clause, the route map executes the continue clause if a successful match occurs. • If the next route map entry does not contain a continue clause, the route map evaluates normally. If a match does not occur, the route map does not continue and falls-through to the next sequence number, if one exists Set a Clause with a Continue Clause If the route-map entry contains sets with the continue clause, the set actions operation is performed first followed by the continue clause jump to the specified route map entry. • If a set actions operation occurs in the first route map entry and then the same set action occurs with a different value in a subsequent route map entry, the last set of actions overrides the previous set of actions with the same set command. • If the set community additive and set as-path prepend commands are configured, the communities and AS numbers are prepended. Enabling MBGP Configurations Multiprotocol BGP (MBGP) is an enhanced BGP that carries IP multicast routes. BGP carries two sets of routes: one set for unicast routing and one set for multicast routing. The routes associated with multicast routing are used by the protocol independent multicast (PIM) to build data distribution trees. Dell Networking OS MBGP is implemented per RFC 1858. You can enable the MBGP feature per router and/or per peer/peer-group. The default is IPv4 Unicast routes. When you configure a peer to support IPv4 multicast, Dell Networking OS takes the following actions: • Send a capacity advertisement to the peer in the BGP Open message specifying IPv4 multicast as a supported AFI/SAFI (Subsequent Address Family Identifier). • If the corresponding capability is received in the peer's Open message, BGP marks the peer as supporting the AFI/SAFI. • When exchanging updates with the peer, BGP sends and receives IPv4 multicast routes if the peer is marked as supporting that AFI/ SAFI. • Exchange of IPv4 multicast route information occurs through the use of two new attributes called MP_REACH_NLRI and MP_UNREACH_NLRI, for feasible and withdrawn routes, respectively. Border Gateway Protocol IPv4 (BGPv4) 215