1 / 8

Adding Acknowledgement Congestion Control to TCP

Adding Acknowledgement Congestion Control to TCP. S. Floyd, A. Arcia, D. Ros, and J. Iyengar draft-floyd-tcpm-ackcc-01.txt TCPM July 2007. What is this draft about?. Adding an optional congestion control mechanism to TCP for pure ack traffic.

abigail-moore
Download Presentation

Adding Acknowledgement Congestion Control to TCP

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Adding Acknowledgement Congestion Control to TCP S. Floyd, A. Arcia, D. Ros, and J. Iyengar draft-floyd-tcpm-ackcc-01.txt TCPM July 2007

  2. What is this draft about? • Adding an optional congestion control mechanism to TCP for pure ack traffic. • Based on the ack congestion control (ackcc) in DCCP’s CCID 2. • Urgent? Nope. • Useful? Probably. • E.g., TCP connections over asymmetric links. • Reducing congestion for aggregate traffic. • Questions? Many.

  3. How would TCP’s ackcc work? • Negotiation between sender and receiver: • (Ack-Congestion-Control-Permitted option). • Start with an Ack Ratio of 2. • The sender detects lost Ack packets: • And tells the receiver the new Ack Ratio. • The sender uses Appropriate Byte Counting and rate-based pacing (in response to Acks acking more than two packets).

  4. Related work: • BPK97, Balakrishnan et al.: • Based on ECN, sender reporting ECN-marked ACK packets to receiver. • TJW00, Ming-Chit et al.: • Receiver-based Ack congestion control. • CCID-2, Floyd and Kohler: • The sender detects lost or marked ACKs, • computes the desired ACK ratio, • tells the receiver.

  5. Possible Complications: • Delayed acknowledgements. • Duplicate acknowledgements. • Two-way traffic. • Reordering of Ack packets. • Abrupt changes in the Ack path. • …

  6. Congestion on the reverse path: • Does pure Ack traffic really contribute to congestion? • Yes, somewhat, if the queue is in units of packets. • Measurement studies of congested links? • How might ackcc be useful to the connection? • ECN-capable ACK packets. • Possibly reducing the ACK drop rate even without ECN. • How might ackcc be harmful to the connection? • Costs of a larger Ack Ratio.

  7. Security Considerations: • Cheating with ECN-capable ACK packets? • If the receiver cheats, the sender could detect it. • If the sender cheats, the receiver can’t easily detect it. • Middleboxes probably could detect it.

  8. Questions: • A TCPM work item, for Experimental? • Feedback?

More Related