Open Messages

After a TCP connection is established between two BGP systems, they exchange BGP open messages to create a BGP connection between them. Once the connection is established, the two systems can exchange BGP messages and data traffic.

Open messages consist of the BGP header plus the following fields:

• Version—The current BGP version number is 4.
• Local AS number—You configure this by including the autonomous-system statement at the [edit routing-options] or [edit logical-systems logical-system-name routing-options] hierarchy levels.
• Hold time—Proposed hold-time value. You configure the local hold time with the BGP hold-time statement.
• BGP identifier—IP address of the BGP system. This address is determined when the system starts up and is the same for every local interface and every BGP peer. You can configure the BGP identifier with the router-id statement at the [edit routing-options] or [edit logical-systems logical-system-name routing-options] hierarchy levels. By default, BGP uses the IP address of the first interface it finds in the router.
• Parameter field length and the parameter itself—These are optional fields.

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