Operation Manual – IPv4 Routing
H3C S3610&S5510 Series Ethernet Switches
Chapter 5 BGP Configuration
5-3
z
Length: The 2-byte unsigned integer indicates the total length of the message.
z
Type: This 1-byte unsigned integer indicates the type code of the message. The
following type codes are defined: 1–Open, 2-Update, 3-Notification, 4–Keepalive,
and 5–Route-refresh. The former four are defined in RFC1771, the last one
defined in RFC2918.
II. Open
After a TCP connection is established, the first message sent by each side is an Open
message for peer relationship establishment. The Open message contains the
following fields:
Figure 5-2
BGP open message format
z
Version: This 1-byte unsigned integer indicates the protocol version number of the
message. The current BGP version is 4.
z
My Autonomous System: This 2-byte unsigned integer indicates the Autonomous
System number of the sender.
z
Hold Time: When establishing peer relationship, two parties negotiate an identical
hold time. If no Keepalive or Update is received from a peer after the hold time, the
BGP connection is considered down.
z
BGP Identifier: In IP address format, identifying the BGP router
z
Opt Parm Len (Optional Parameters Length): Length of optional parameters, set
to 0 if no optional parameter is available
III. Update
The Update messages are used to exchange routing information between peers. It can
advertise a feasible route or remove multiple unfeasible routes. Its format is shown
below:
