BGP Open Message
An OPEN message is sent after the TCP three-way handshake is completed. The BGP OPEN message is used to open a BGP session. The OPEN message contains information about the BGP neighbor initiating the session, and information about supported and negotiated options including:
- BGP Version number
- AS Number
- Hold Down Time value
- BGP Identifier
- Optional Parameters
- Optional Parameters length (0-255 in bytes)
OPEN MESSAGE FORMAT
| Version (8 bits) |
My AS NUMBER (16 Bits) |
Hold Down Timer (16 bits) |
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| BGP ID (32 bits) |
Optional Parameters Length (8 bits) |
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| Optional Parameters (Variable number of bytes) |
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