Huawei S6700 Series Configuration Manual page 386

S6700 Series Ethernet Switches
Configuration Guide - IP Routing
Introduction to MP-BGP
Traditional BGP-4 manages only IPv4 unicast routing information and has limitations in inter-
AS routing when used in the applications of other network layer protocols such as IPv6.
To support multiple network layer protocols, the Internet Engineering Task Force (IETF) extends
BGP-4 to Multiprotocol Extensions for BGP-4 (MP-BGP). The current MP-BGP standard is
RFC 2858 (Multiprotocol Extensions for BGP-4).
MP-BGP is forward compatible. That is, the switchs that support MP-BGP can communicate
with the switchs that do not support MP-BGP.
Extended Attributes of MP-BGP
Among BGP-4 packets, an Update packet carries three IPv4-related attributes: Network Layer
Reachability Information (NLRI), Next_Hop, and Aggregator. The Aggregator attribute
contains the IP address of the BGP speaker that performs route summarization.
To support multiple types of network layer protocols, BGP-4 needs to carry network layer
protocol information in the NLRI attribute and Next_Hop attribute. MP-BGP introduces two
new route attributes:
l
l
The two new attributes are optional non-transitive. Therefore, the BGP speakers that do not
support the multiprotocol capability will ignore the two attributes, and do not advertise the
information to peers.
Address Family
BGP uses address families to distinguish different network layer protocols. For the values of
address families, see RFC 1700 (Assigned Numbers). The S6700 supports multiple MP-BGP
extensions, such as VPN extension and IPv6 extension, which are configured in their respective
address family views.
BGP Tracking
BGP tracking speeds up network convergence by adjusting the interval between peer
unreachbility discovery and connection interruption. It is easy to deploy and has a good
extensibility.
Issue 01 (2012-03-15)
Multiprotocol Reachable NLRI (MP_REACH_NLRI): It is used to advertise reachable
routes and next hops.
Multiprotocol Unreachable NLRI (MP_UNREACH_NLRI): It is used to withdraw
unreachable routes.
NOTE
This chapter does not describe the commands related to a specific application in the MP-BGP address
family view.
For the configuration in the BGP IPv6 address family view, see the chapter "BGP4+ Configuration." For
the application of MP-BGP in multicast, see the chapter "MBGP Configuration" in the S6700 Series
Ethernet Switches Configuration Guide - IP Multicast.
For the configuration in the BGP VPNv4 address family view, BGP VPN instance address family view,
and BGP L2VPN address family view, see the S6700 Series Ethernet Switches Configuration Guide -
VPN.
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