draft-ietf-tcpm-alternativebackoff-ecn-08.txt | draft-ietf-tcpm-alternativebackoff-ecn-09.txt | |||
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Network Working Group N. Khademi | Network Working Group N. Khademi | |||
Internet-Draft M. Welzl | Internet-Draft M. Welzl | |||
Intended status: Experimental University of Oslo | Intended status: Experimental University of Oslo | |||
Expires: February 8, 2019 G. Armitage | Expires: February 15, 2019 G. Armitage | |||
Netflix | Netflix | |||
G. Fairhurst | G. Fairhurst | |||
University of Aberdeen | University of Aberdeen | |||
August 7, 2018 | August 14, 2018 | |||
TCP Alternative Backoff with ECN (ABE) | TCP Alternative Backoff with ECN (ABE) | |||
draft-ietf-tcpm-alternativebackoff-ecn-08 | draft-ietf-tcpm-alternativebackoff-ecn-09 | |||
Abstract | Abstract | |||
Active Queue Management (AQM) mechanisms allow for burst tolerance | Active Queue Management (AQM) mechanisms allow for burst tolerance | |||
while enforcing short queues to minimise the time that packets spend | while enforcing short queues to minimise the time that packets spend | |||
enqueued at a bottleneck. This can cause noticeable performance | enqueued at a bottleneck. This can cause noticeable performance | |||
degradation for TCP connections traversing such a bottleneck, | degradation for TCP connections traversing such a bottleneck, | |||
especially if there are only a few flows or their bandwidth-delay- | especially if there are only a few flows or their bandwidth-delay- | |||
product is large. The reception of a Congestion Experienced (CE) ECN | product is large. The reception of a Congestion Experienced (CE) ECN | |||
mark indicates that an AQM mechanism is used at the bottleneck, and | mark indicates that an AQM mechanism is used at the bottleneck, and | |||
skipping to change at page 1, line 47 ¶ | skipping to change at page 1, line 47 ¶ | |||
Internet-Drafts are working documents of the Internet Engineering | Internet-Drafts are working documents of the Internet Engineering | |||
Task Force (IETF). Note that other groups may also distribute | Task Force (IETF). Note that other groups may also distribute | |||
working documents as Internet-Drafts. The list of current Internet- | working documents as Internet-Drafts. The list of current Internet- | |||
Drafts is at https://datatracker.ietf.org/drafts/current/. | Drafts is at https://datatracker.ietf.org/drafts/current/. | |||
Internet-Drafts are draft documents valid for a maximum of six months | Internet-Drafts are draft documents valid for a maximum of six months | |||
and may be updated, replaced, or obsoleted by other documents at any | and may be updated, replaced, or obsoleted by other documents at any | |||
time. It is inappropriate to use Internet-Drafts as reference | time. It is inappropriate to use Internet-Drafts as reference | |||
material or to cite them other than as "work in progress." | material or to cite them other than as "work in progress." | |||
This Internet-Draft will expire on February 8, 2019. | This Internet-Draft will expire on February 15, 2019. | |||
Copyright Notice | Copyright Notice | |||
Copyright (c) 2018 IETF Trust and the persons identified as the | Copyright (c) 2018 IETF Trust and the persons identified as the | |||
document authors. All rights reserved. | document authors. All rights reserved. | |||
This document is subject to BCP 78 and the IETF Trust's Legal | This document is subject to BCP 78 and the IETF Trust's Legal | |||
Provisions Relating to IETF Documents | Provisions Relating to IETF Documents | |||
(https://trustee.ietf.org/license-info) in effect on the date of | (https://trustee.ietf.org/license-info) in effect on the date of | |||
publication of this document. Please review these documents | publication of this document. Please review these documents | |||
skipping to change at page 4, line 23 ¶ | skipping to change at page 4, line 23 ¶ | |||
The TCP sender response is currently specified in section 6.1.2 of | The TCP sender response is currently specified in section 6.1.2 of | |||
the ECN specification [RFC3168], updated by [RFC8311]: | the ECN specification [RFC3168], updated by [RFC8311]: | |||
The indication of congestion should be treated just as a | The indication of congestion should be treated just as a | |||
congestion loss in non-ECN-Capable TCP. That is, the TCP source | congestion loss in non-ECN-Capable TCP. That is, the TCP source | |||
halves the congestion window "cwnd" and reduces the slow start | halves the congestion window "cwnd" and reduces the slow start | |||
threshold "ssthresh", unless otherwise specified by an | threshold "ssthresh", unless otherwise specified by an | |||
Experimental RFC in the IETF document stream. | Experimental RFC in the IETF document stream. | |||
This is replaced with: | Following publication of RFC8311, this document specifies a sender- | |||
side change to TCP: | ||||
Receipt of a packet with the ECN-Echo flag SHOULD trigger the TCP | Receipt of a packet with the ECN-Echo flag SHOULD trigger the TCP | |||
source to set the slow start threshold (ssthresh) to 0.8 times the | source to set the slow start threshold (ssthresh) to 0.8 times the | |||
FlightSize, with a lower bound of 2 * SMSS applied to the result. | FlightSize, with a lower bound of 2 * SMSS applied to the result. | |||
As in [RFC5681], the TCP sender also reduces the cwnd value to no | As in [RFC5681], the TCP sender also reduces the cwnd value to no | |||
more than the new ssthresh value. RFC 3168 section 6.1.2 provides | more than the new ssthresh value. RFC 3168 section 6.1.2 provides | |||
guidance on setting a cwnd less than 2 * SMSS. | guidance on setting a cwnd less than 2 * SMSS. | |||
3.1. Choice of ABE Multiplier | 3.1. Choice of ABE Multiplier | |||
skipping to change at page 9, line 41 ¶ | skipping to change at page 9, line 41 ¶ | |||
mechanisms that have been in use in the Internet for many years | mechanisms that have been in use in the Internet for many years | |||
(e.g., CUBIC [RFC8312]). Unfairness may also be a result of other | (e.g., CUBIC [RFC8312]). Unfairness may also be a result of other | |||
factors, including the round trip time experienced by a flow. ABE | factors, including the round trip time experienced by a flow. ABE | |||
applies only when ECN-marked packets are received, not when packets | applies only when ECN-marked packets are received, not when packets | |||
are lost, hence use of ABE cannot lead to congestion collapse. | are lost, hence use of ABE cannot lead to congestion collapse. | |||
11. Revision Information | 11. Revision Information | |||
XX RFC ED - PLEASE REMOVE THIS SECTION XXX | XX RFC ED - PLEASE REMOVE THIS SECTION XXX | |||
-09. Chnaged to "Following publication of RFC8311, this document | ||||
specifies a sender-side change to TCP:" | ||||
-08. Addressed comments from AD review on the document structure, | -08. Addressed comments from AD review on the document structure, | |||
and relationship to existing RFCs. | and relationship to existing RFCs. | |||
-07. Addressed comments following WGLC. | -07. Addressed comments following WGLC. | |||
o Updated Reference citations. | o Updated Reference citations. | |||
o Removed paragraph containing a wrong statement related to timeout | o Removed paragraph containing a wrong statement related to timeout | |||
in section 4.1. | in section 4.1. | |||
End of changes. 6 change blocks. | ||||
5 lines changed or deleted | 9 lines changed or added | |||
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