Concept Guide

MBGP allows information about the topology of the IP multicast-capable routers to be exchanged separately from the topology of normal
IPv4 and IPv6 unicast routers. It allows a multicast routing topology dierent from the unicast routing topology.
MBGP uses either an IPv4 address congured on the interface (which is used to establish the IPv6 session) or a stable IPv4 address that is
available in the box as the next-hop address. As a result, while advertising an IPv6 network, exchange of IPv4 routes does not lead to
martian next-hop message logs.
NOTE: It is possible to congure BGP peers that exchange both unicast and multicast network layer reachability information
(NLRI), but you cannot connect multiprotocol BGP with BGP. Therefore, you cannot redistribute multiprotocol BGP routes into
BGP.
MBGP for IPv4 Multicast
PIM feature uses IPv4 multicast routing for data distribution. MBGP provides a link that is dedicated specic to multicast trac. MBGP
also allows a unicast routing apart from the multicast routing. A multicast routing protocol, such as PIM, uses both the unicast and
multicast BGP database to form a routing table for unicast and multicast. You can congure BGP peers that exchange both unicast and
multicast Network Layer Reachability Information (NLRI) in which MBGP routes is redistributed into BGP. The default is IPv4 unicast.
IPv4 and IPv6 address family
The IPv4 address family conguration in Dell EMC Networking OS is used for identifying routing sessions for protocols that use IPv4
address. You can specify multicast within the IPv4 address family. The default of address family conguration is IPv4 unicast. You can
congure the VRF instances for IPv4 address family conguration.
The IPv6 address family conguration is used for identifying routing sessions for protocols that use IPv6 address. You can specify unicast
within the IPv6 address family. You can congure the VRF instances for IPv6 address family conguration.
BGP address family model
Dell EMC Networking OS supports BGP address family identier (AFI) with MBGP to provide scalability for multiple AFI and subsequent
address family identier (SAFI) congurations. MBGP carries routing information for address families (IPv4 and IPv6) of multiple network-
layer protocols. Each address family has a separated BGP database, so that you can congure BGP policy based on address family.
BGP global and address family conguration
Implementing BGP is divided into global and address family conguration.
BGP conguration command levels are grouped as high level and address family conguration. All independent commands are grouped at
the beginning of the conguration and followed by separate sub commands specic to each address family.
Following is the order of BGP conguration:
• Global conguration — General conguration that is applied to BGP. For example, conguring BGP timer, Adding additional BGP paths,
etc.
• Address family conguration — Congurations that are applied to a specic address family.
The BGP address family model consists of three address families such as IPv4 unicast, IPv4 multicast, and IPv6 unicast. The default
address family is IPv4 unicast. The neighbors congured under CONFIGURATION-ROUTER-BGP mode is considered to be IPv4 unicast
neighbor. The IPv4 routes are advertised or received irrespective of the address family conguration. To congure a neighbor for IPv4
multicast or IPv6 unicast, you have to create an appropriate address family and activate the neighbor in the respective address family
conguration, as shown the following example conguration.
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Border Gateway Protocol (BGP)