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:

1. BGP Version number
2. AS Number
3. Hold Down Time value
4. BGP Identifier
5. Optional Parameters
6. Optional Parameters length (0-255 in bytes)

OPEN MESSAGE FORMAT

Version (8 bits)	My AS NUMBER (16 Bits)	Hold Down Timer (16 bits)
BGP ID (32 bits)			Optional Parameters Length (8 bits)
Optional Parameters (Variable number of bytes)

 

 

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