BPG Common Header
261
Endpoints typically stay in the Established state until there is a loss of the
session or an error. If this occurs, then the connection returns to the Idle state
and all the information that the BGP endpoints have learned from their
neighboring endpoint will be purged from the BGP routing table.
BPG Common Header
A
common header precedes all BGP messages. This header, shown in
Figure 7.7, contains the following fields:
Marker
Length
Type
We will discuss those fields in the following sections.
F I G U R E 7 . 7
The BGP common header
Marker
The Marker field is a field up to two bytes long. It is used for security and
synchronization. The value of this field depends on the type of message
being sent.
Length
The Length field indicates the size of the entire BGP message including the
header.
Marker
(16 octets)
Length
(2 octets)
Type
(1 octets)
More fields based
on message type
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