Книга: Iptables Tutorial 1.2.2

SCTP SHUTDOWN chunk

SCTP SHUTDOWN chunk

The SHUTDOWN chunk is issued when one of the endpoints of a connection wants to close the current association. The sending party must empty all of its sending buffers before sending the SHUTDOWN chunk, and must not send any more DATA chunks afterwards. The receiver must also empty its sending buffers and must then send the responding SHUTDOWN ACK chunk.

Type - bit 0-7. This header is always set to 7 for SHUTDOWN chunks.

Chunk flags - bit 8-15. Not used today. Might be applicable for change. See SCTP Common and generic headers for more information.

Chunk Length - bit 16-31. The chunk length is the length of the whole packet, including the Cumulative TSN Ack parameter. The length of the SHUTDOWN chunk should always be 8.

Cumulative TSN Ack - bit 32-63. This is a Cumulative TSN Ack field, just the same as in the SACK chunk. The Cumulative TSN Ack acknowledges the last TSN received in sequence from the opposite endpoint. This parameter does not, nor can the rest of the SHUTDOWN chunk either, acknowledge Gap Ack Blocks. The lack of a Gap Ack Block in the SHUTDOWN chunk that was acknowledged before should not be interpreted as if the previously acknowledged block was lost again.

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