Mp-bgp, Mp-bgp extended attributes – H3C Technologies H3C S5560 Series Switches User Manual

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When the BGP routers in an AS are fully meshed, route reflection is unnecessary because it

consumes more bandwidth resources. You can use commands to disable route reflection instead of
modifying network configuration or changing network topology.
After route reflection is disabled between clients, routes can still be reflected between a client and
a non-client.

Confederation
Confederation is another method to manage growing IBGP connections in an AS. It splits an AS
into multiple sub-ASs. In each sub-AS, IBGP peers are fully meshed. As shown in

Figure 56

,

intra-confederation EBGP connections are established between sub-ASs in AS 200.

Figure 56 Confederation network diagram

A non-confederation BGP speaker does not need to know sub-ASs in the confederation. It
considers the confederation as one AS, and the confederation ID as the AS number. In the above

figure, AS 200 is the confederation ID.
Confederation has a deficiency. When you change an AS into a confederation, you must
reconfigure the routers, and the topology will be changed.
In large-scale BGP networks, you can use both route reflector and confederation.

MP-BGP

BGP-4 carries only IPv4 unicast routing information. IETF extended BGP-4 by introducing Multiprotocol

Extensions for BGP-4 (MP-BGP). MP-BGP can carry routing information for multiple address families,

including IPv4 multicast, IPv6 unicast, IPv6 multicast, and VPNv4.
MP-BGP is backward compatible with BGP.

MP-BGP extended attributes

Prefixes and next hops are key routing information. BGP-4 uses update messages to carry the following

information:

Feasible route prefixes in the Network Layer Reachability Information (NLRI) field.

Unfeasible route prefixes in the withdrawn routes field.

Next hops in the NEXT_HOP attribute.

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