Formats Of Bgp Messages - H3C S3610-28P Operation Manual

Operation Manual – IPv4 Routing
H3C S3610&S5510 Series Ethernet Switches
Supporting CIDR
Substantially reducing bandwidth occupation by advertising updating routes only
and applicable to advertising a great amount of routing information on the Internet
Eliminating route loops completely by adding AS path information to BGP routes
Providing abundant routing policies to implement flexible route filtering and
selection
Easy to extend, satisfying new network developments
A router advertising BGP messages is called a BGP speaker, which exchanges new
routing information with other BGP speakers. When a BGP speaker receives a new
route or a route better than the current one from another AS, it will advertise the route to
all the other BGP speakers in the local AS.
BGP speakers call each other peers, and several associated peers form a peer group.
BGP runs on a router in one of the following two modes:
IBGP (Interior BGP)
EBGP (External BGP)
BGP is called IBGP when it runs within an AS and is called EBGP when it runs between
ASs.

5.1.1 Formats of BGP Messages

I. Header
BGP has five types of messages:
Open
Update
Notification
Keep-alive
Route-refresh
They have the same header, as shown below:
Figure 5-1 BGP message header
Marker: The 16-byte field is used for BGP authentication. If no authentication
information is available, then the Marker must be all ones.
5-2
Chapter 5 BGP Configuration