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MBGP configuration (available only on the
A5500 EI)
NOTE:
The term
router
in this document refers to both routers and Layer 3 switches.
This document covers configuration tasks related to multiprotocol BGP for IP multicast only. For more
information about BGP, see the
Layer 3—IP Routing Configuration Guide
.
For more information about RPF, see the chapter “Multicast routing and forwarding configuration.”
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.
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
Complete the following tasks to configure MBGP:
Task Remarks
Configuring MBGP basic functions Required
Controlling route
advertisement and
Configuring MBGP route redistribution Required
Configure default route redistribution into MBGP Optional
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