draft-ietf-avtcore-rtp-circuit-breakers-17.txt   draft-ietf-avtcore-rtp-circuit-breakers-18.txt 
AVTCORE Working Group C. Perkins AVTCORE Working Group C. Perkins
Internet-Draft University of Glasgow Internet-Draft University of Glasgow
Updates: 3550 (if approved) V. Singh Updates: 3550 (if approved) V. Singh
Intended status: Standards Track callstats.io Intended status: Standards Track callstats.io
Expires: January 21, 2017 July 20, 2016 Expires: February 19, 2017 August 18, 2016
Multimedia Congestion Control: Circuit Breakers for Unicast RTP Sessions Multimedia Congestion Control: Circuit Breakers for Unicast RTP Sessions
draft-ietf-avtcore-rtp-circuit-breakers-17 draft-ietf-avtcore-rtp-circuit-breakers-18
Abstract Abstract
The Real-time Transport Protocol (RTP) is widely used in telephony, The Real-time Transport Protocol (RTP) is widely used in telephony,
video conferencing, and telepresence applications. Such applications video conferencing, and telepresence applications. Such applications
are often run on best-effort UDP/IP networks. If congestion control are often run on best-effort UDP/IP networks. If congestion control
is not implemented in these applications, then network congestion can is not implemented in these applications, then network congestion can
lead to uncontrolled packet loss, and a resulting deterioration of lead to uncontrolled packet loss, and a resulting deterioration of
the user's multimedia experience. The congestion control algorithm the user's multimedia experience. The congestion control algorithm
acts as a safety measure, stopping RTP flows from using excessive acts as a safety measure, stopping RTP flows from using excessive
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This Internet-Draft will expire on January 21, 2017. This Internet-Draft will expire on February 19, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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
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such, the congestion circuit breaker will almost certainly trigger to such, the congestion circuit breaker will almost certainly trigger to
stop flows where the media would be unusable due to high packet loss stop flows where the media would be unusable due to high packet loss
or latency. However, in pathological scenarios where the congestion or latency. However, in pathological scenarios where the congestion
circuit breaker does not stop the flow, it is desirable to prevent circuit breaker does not stop the flow, it is desirable to prevent
the application sending unnecessary traffic that might disrupt other the application sending unnecessary traffic that might disrupt other
uses of the network. The role of the media usability circuit breaker uses of the network. The role of the media usability circuit breaker
is to protect the network in such cases. is to protect the network in such cases.
4.5. Ceasing Transmission 4.5. Ceasing Transmission
What it means to cease transmission depends on the application. The What it means to cease transmission depends on the application. This
intention is that the application will stop sending RTP data packets
on a particular 5-tuple (transport protocol, source and destination
ports, source and destination IP addresses), until whatever network
problem that triggered the RTP circuit breaker has dissipated. This
could mean stopping a single RTP flow, or it could mean that multiple could mean stopping a single RTP flow, or it could mean that multiple
bundled RTP flows are stopped. RTP flows halted by the circuit bundled RTP flows are stopped. The intention is that the application
will stop sending RTP data packets on a particular 5-tuple (transport
protocol, source and destination ports, source and destination IP
addresses), until whatever network problem that triggered the RTP
circuit breaker has dissipated. RTP flows halted by the circuit
breaker SHOULD NOT be restarted automatically unless the sender has breaker SHOULD NOT be restarted automatically unless the sender has
received information that the congestion has dissipated, or can received information that the congestion has dissipated, or can
reasonably be expected to have dissipated. What could trigger this reasonably be expected to have dissipated. What could trigger this
expectation is necessarily application dependent, but could be, for expectation is necessarily application dependent, but could be, for
example, an indication that a competing flow has finished and freed example, an indication that a competing flow has finished and freed
up some capacity, or for an application running on a mobile device, up some capacity, or for an application running on a mobile device,
that the device moved to a new location so the flow would traverse a that the device moved to a new location so the flow would traverse a
different path if it were restarted. Ideally, a human user will be different path if it were restarted. Ideally, a human user will be
involved in the decision to try to restart the flow, since that user involved in the decision to try to restart the flow, since that user
will eventually give up if the flows repeatedly trigger the circuit will eventually give up if the flows repeatedly trigger the circuit
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