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Configuring MBGP
This chapter covers configuration tasks related to MBGP for IP multicast only. For more information
about BGP, see
Layer 3—IP Routing Configuration Guide
.
Overview
BGP-4 can only carry routing information for IPv4. 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. For more information
about RPF, see "
Configuring multicast routing and forwarding
."
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.
MP-BGP is defined in RFC 2858 (Multiprotocol Extensions for BGP-4). The application of MP-BGP
for 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