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Configuring MBGP
This chapter covers configuration tasks related to multiprotocol BGP for IP multicast only. For more
information about BGP, see Layer 3—IP Routing Configuration Guide.
The term "router" in this chapter refers to both routers and Layer 3 switches.
MBGP overview
BGP-4 can carry routing information for IPv4 only. IETF defined Multiprotocol Border Gateway Protocol
(MP-BGP) to extend BGP-4 so that BGP can carry routing information for multiple network-layer protocols.
For a network, the topology for multicast might be different from that for unicast. To distinguish them, the
MP-BGP enables BGP to carry the unicast Network Layer Reachability Information (NLRI) and multicast
NLRI separately. The multicast NLRI performs reverse path forwarding (RPF) exclusively. In this way, route
selection for a destination through the unicast routing table and through the multicast routing table have
different results, ensuring consistent unicast forwarding and normal multicast between domains. For
more information about RPF, see "Configuring multicast routing and forwarding."
MP-BGP is defined in RFC 2858 (Multiprotocol Extensions for BGP-4). The application of MP-BGP on
multicast is called Multicast BGP (MBGP).
Protocols and standards
• RFC 2858, Multiprotocol Extensions for BGP-4
• RFC 3392, Capabilities Advertisement with BGP-4
• draft-ietf-idmr-bgp-mcast-attr-00, BGP Attributes for Multicast Tree Construction
• RFC 4271, A Border Gateway Protocol 4 (BGP-4)
• RFC 5291, Outbound Route Filtering Capability for BGP-4
• RFC 5292, Address-Prefix-Based Outbound Route Filter for BGP-4
MBGP configuration task list
Task Remarks
Configuring basic MBGP functions Required
Controlling route
advertisement and
reception
Configuring MBGP route redistribution Required
Configuring default route redistribution into MBGP Optional
Configuring MBGP route summarization Optional
Advertising a default route to an IPv4 MBGP peer or peer group Optional
Configuring outbound MBGP route filtering Optional
Configuring inbound MBGP route filtering Optional
Configuring MBGP route dampening Optional
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