ECN++: Adding Explicit Congestion Notification (ECN) to TCP Control Packets
draft-bagnulo-tcpm-generalized-ecn-04
Network Working Group M. Bagnulo
Internet-Draft UC3M
Intended status: Experimental B. Briscoe
Expires: November 20, 2017 Simula Research Lab
May 19, 2017
ECN++: Adding Explicit Congestion Notification (ECN) to TCP Control
Packets
draft-bagnulo-tcpm-generalized-ecn-04
Abstract
This document describes an experimental modification to ECN when used
with TCP. It allows the use of ECN on the following TCP packets:
SYNs, pure ACKs, Window probes, FINs, RSTs and retransmissions.
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Bagnulo & Briscoe Expires November 20, 2017 [Page 1]
Internet-Draft ECN++ May 2017
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Experiment Goals . . . . . . . . . . . . . . . . . . . . 4
1.3. Document Structure . . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Specification . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Network (e.g. Firewall) Behaviour . . . . . . . . . . . . 6
3.2. Endpoint Behaviour . . . . . . . . . . . . . . . . . . . 6
3.2.1. SYN . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2.2. SYN-ACK . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.3. Pure ACK . . . . . . . . . . . . . . . . . . . . . . 12
3.2.4. Window Probe . . . . . . . . . . . . . . . . . . . . 13
3.2.5. FIN . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2.6. RST . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2.7. Retransmissions . . . . . . . . . . . . . . . . . . . 14
4. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1. The Reliability Argument . . . . . . . . . . . . . . . . 15
4.2. SYNs . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.2.1. Argument 1a: Unrecognized CE on the SYN . . . . . . . 16
4.2.2. Argument 1b: Unrecognized ECT on the SYN . . . . . . 18
4.2.3. Argument 2: DoS Attacks . . . . . . . . . . . . . . . 20
4.3. SYN-ACKs . . . . . . . . . . . . . . . . . . . . . . . . 20
4.4. Pure ACKs . . . . . . . . . . . . . . . . . . . . . . . . 22
4.4.1. Cwnd Response to CE-Marked Pure ACKs . . . . . . . . 23
4.4.2. ACK Rate Response to CE-Marked Pure ACKs . . . . . . 24
4.4.3. Summary: Enabling ECN on Pure ACKs . . . . . . . . . 25
4.5. Window Probes . . . . . . . . . . . . . . . . . . . . . . 25
4.6. FINs . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.7. RSTs . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.8. Retransmitted Packets. . . . . . . . . . . . . . . . . . 27
5. Interaction with popular variants or derivatives of TCP . . . 28
5.1. SCTP . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.2. IW10 . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.3. TFO . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6. Security Considerations . . . . . . . . . . . . . . . . . . . 30
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