Administrator Guide

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MP_UNREACH_NLRI, for feasible and withdrawn routes, respectively.
● If the peer has not been activated in any AFI/SAFI, the peer remains in Idle state.
Most Dell Networking OS 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
neighbor [ip-address | peer-group-name] activate
BGP Regular Expression Optimization
Dell Networking OS optimizes processing time when using regular expressions by caching and re-using regular expression
evaluated results, at the expense of some memory in RP1 processor.
BGP policies that contain regular expressions to match against as-paths and communities might take a lot of CPU processing
time, thus affect BGP routing convergence. Also, show bgp commands that get filtered through regular expressions can to
take a lot of CPU cycles, especially when the database is large.
This feature is turned on by default. If necessary, use the bgp regex-eval-optz-disable command in CONFIGURATION
ROUTER BGP mode to disable it.
Debugging BGP
To enable BGP debugging, use any of the following commands.
● View all information about BGP, including BGP events, keepalives, notifications, and updates.
EXEC Privilege mode
180
Border Gateway Protocol IPv4 (BGPv4)