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6 Cards in this Set
- Front
- Back
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Idle
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Initiates a TCP connection with its configured peer and listens for a response. Changes state to connect.
Can fail and remain in Idle if TCP port 179 is not open, a random TCP port above 1023 is not open, or peer IP or AS is misconfigured |
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Connect
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Waits for TCP negotiation with peer
If TCP successful, sends OPEN and moves to OpenSent If error (TCP port, IP/AS misconfig), moves to Active |
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Active
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BGP was unable to establish a TCP connection. Retries once, if unsuccessful moves to Idle state.
Failure can be caused by TCP ports not open, IP/AS misconfig, or network congestion / flapping. |
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OpenSent
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BGP listens for Open from peer. Once received, router checks validity and sends Notification message with error. Otherwise sends KeepAlive and moves to OpenConfirm.
Possible issues: version mismatch, MD5 pw mismatch, wrong AS |
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OpenConfirm
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Listening for KeepAlive from peer. If received and no timers expired, move to Established.
If a timer expires or an error is received, goes back to Idle. |
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Established
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Peers send Update messages to exchange prefixes. If any errors are received, goes back to Idle.
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