36 IPV6 BGP CONFIGURATIONn This chapter describes only configuration for IPv6 BGP. For other relatedinformation, refer to “BGP Configuration” on page 365.When configuring IPv6 BGP, go to these sections for information you areinterested in:■ “IPv6 BGP Overview” on page 467■ “Configuration Task List” on page 468■ “Configuring IPv6 BGP Basic Functions” on page 469■ “Controlling Route Distribution and Reception” on page 471■ “Configuring IPv6 BGP Route Attributes” on page 474■ “Tuning and Optimizing IPv6 BGP Networks” on page 476■ “Configuring a Large Scale IPv6 BGP Network” on page 478■ “Displaying and Maintaining IPv6 BGP Configuration” on page 482■ “IPv6 BGP Configuration Examples” on page 483■ “Troubleshooting IPv6 BGP Configuration” on page 486IPv6 BGP Overview BGP-4 manages only IPv4 routing information, thus other network layer protocolssuch as IPv6 are not supported.To support multiple network layer protocols, IETF extended BGP-4 by introducingIPv6 BGP that is defined in RFC 2858 (multiprotocol extensions for BGP-4).To implement IPv6 support, IPv6 BGP puts IPv6 network layer information into theattributes of network layer reachable information (NLRI) and NEXT_HOP.NLRI attribute of IPv6 BGP involves:■ MP_REACH_NLRI: Multiprotocol Reachable NLRI, for advertisement of next hopinformation of reachable routes.■ MP_UNREACH_NLRI: Multiprotocol Unreachable NLRI, for withdrawal ofunreachable routes.The NEXT_HOP attribute of IPv6 BGP is identified by an IPv6 unicast address orIPv6 local link address.IPv6 BGP utilizes BGP multiprotocol extensions for application in IPv6 networks.The original messaging and routing mechanisms of BGP are not changed.
