H3C S7500E Series Operation Manual page 418

Operation Manual – IPv4 Routing
H3C S7500E Series Ethernet Switches
Figure 5-15 Confederation network diagram
From the perspective of a non-confederation speaker, it needs not know sub-ASs in the
confederation. The ID of the confederation is the number of the AS. In the above figure,
AS200 is the confederation ID.
The deficiency of confederation is: when changing an AS into a confederation, you
need to reconfigure your routers, and the topology will be changed.
In large-scale BGP networks, both route reflector and confederation can be used.
5.1.6 MP-BGP
I. Overview
The legacy BGP-4 supports IPv4, but does not support other network layer protocols
like IPv6.
To support more network layer protocols, IETF extended BGP-4 by introducing
Multiprotocol Extensions for BGP-4 (MP-BGP), which is defined in RFC2858.
Routers supporting MP-BGP can communicate with routers not supporting MP-BGP.
II. MP-BGP extended attributes
In BGP-4, the three types of attributes for IPv4, namely NLRI, NEXT_HOP and
AGGREGATOR (contains the IP address of the speaker generating the summary route)
are all carried in updates.
To support multiple network layer protocols, BGP-4 puts information about network
layer into NLRI and NEXT_HOP. MP-BGP introduced two path attributes:
MP_REACH_NLRI: Multiprotocol Reachable NLRI, for advertising feasible routes
and next hops
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Chapter 5 BGP Configuration