Concept Guide

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 specied route-map entry. With a match clause and a continue
clause, the match clause executes rst and the continue clause next in a specied 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 specied 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 rst followed by the continue clause
jump to the specied route map entry.
• If a set actions operation occurs in the rst route map entry and then the same set action occurs with a dierent 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 congured, the communities and AS numbers are
prepended.
Enabling MBGP Congurations
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.
MBGP for IPv4 multicast is supported on the switch.
In the 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 congure a peer to support IPv4 multicast, the system 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 Identier).
• 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.
• If the peer has not been activated in any AFI/SAFI, the peer remains in Idle state.
Most BGP IPv4 unicast commands are extended to support the IPv4 multicast RIB using extra options to the command. For a detailed
description of the MBGP commands, refer to the Dell Networking OS Command Line Interface Reference Guide.
• Enables support for the IPv4 multicast family on the BGP node.
CONFIG-ROUTER-BGP mode
address family ipv4 multicast
• Enable IPv4 multicast support on a BGP neighbor/peer group.
CONFIG-ROUTER-BGP-AF (Address Family) mode
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Border Gateway Protocol IPv4 (BGPv4)