Stream Control Transmission Protocol (SCTP) Data Acknowledgement with Non-Renegable Selective Acknowledgements (NR-SACKs).
draft-natarajan-sctp-nrsack-00

Abstract

Stream Control Transmission Protocol (SCTP) [RFC4960] specifies Selective Acknowledgements (SACKs) to allow a transport layer data receiver to acknowledge DATA chunks which arrive out-of-order. In SCTP, SACK information is advisory because the data receiver is permitted to renege; that is, later discard a DATA chunk which previously has been SACKed. Since delivery of a SACKed out-of-order DATA chunk is not guaranteed, a copy of this DATA chunk MUST be kept in the data sender's retransmission queue until this DATA chunk is cumulatively acked. This document specifies Non-Renegable Selective Acknowledgements (NR- SACKs), an extension to SCTP's acknowledgment mechanism. NR-SACKs enable a data receiver to explicitly acknowledge out-of-order DATA chunks that have been delivered to the receiving application. (Recall that, in SCTP, out-of-order data sometimes can be delivered.) NR-SACKs also enable a data receiver to indicate any out-of-order DATA chunks on which the receiver guarantees never to renege. As opposed to SACKed DATA chunks, a sender can consider NR-SACKed DATA chunks as never requiring retransmission, thus freeing space in the data sender's retransmission queue sooner.

Authors

Preethi Natarajan
Professor Paul D. Amer
Ertugrul Yilmaz
Randall R. Stewart
Jana Iyengar

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