draftgomezlwigtcpconstrained nodenetworks03 Carles Gomez Universitat Politècnica de Catalunya Jon Crowcroft University of Cambridge Michael Scharf Nokia IETF 99 Prague July 2017 ID: 812825
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TCP over Constrained-Node Networksdraft-gomez-lwig-tcp-constrained-node-networks-03
Carles Gomez Universitat Politècnica de CatalunyaJon CrowcroftUniversity of CambridgeMichael ScharfNokia
IETF 99 – Prague, July 2017
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Slide2MotivationSeveral application layer protocols being used for the Internet of Things (IoT)Constrained Application Protocol (CoAP)Originally over UDP
CoAP over TCP in progressTo overcome middlebox problemsHTTP/2 and HTTP/1.1XMPPMQTTTCP is being / will be used in many IoT scenariosOffer simple measures for suitable TCP implementation/operation over CNNs
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TCP
Slide3Statusdraft-gomez-core-tcp-constrained-node-networks-00
Presented in IETF 96 (LWIG and TCPM WGs)draft-gomez-lwig-tcp-...-01Presented in IETF 97draft-gomez-lwig-tcp-...-02Presented in IETF 98draft-gomez-lwig-tcp-...-03Feedback from IETF 98Details on RIOT and OpenWSN TCP implementationsThanks to Simon Brummer and Xavi Vilajosana
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Slide4AcknowledgmentCarsten Bormann, Zhen Cao, Wei Genyu, Ari Keranen, Abhijan Bhattacharyya, Andres Arcia-Moret, Yoshifumi Nishida, Joe Touch, Fred Baker, Nik Sultana, Kerry Lynn, Erik Nordmark, Simon
Brummer, Xavi Vilajosana, Rahul Jadhav. 4
Slide5Updates in -03 (I/V)4.2. Maximum Segment Size (MSS)RFC 1981: technologies that support an MTU > 1280 bytesSHOULD support PMTU discovery
A minimal IPv6 implementation may choose to omit implementation of PMTU discoveryUnless applications require handling large data units (IPv6 datagram size > 1280 bytes)Desirable to limit the MTU to 1280 bytes5
Slide6Updates in -03 (II/V)4.8. Delayed AcknowledgmentsConstrained device sending data to a peerIf Delayed ACKs are enabled at the peerACKs may be delayed by, typically, 200
msTransactional-type trafficUnnecessary delayDisabling Delayed ACKs is recommendedPossible if the peer is administered by the same entity managing the CNN
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Slide7Updates in -02 (III/V)7.3. RIOT TCP implementationDesigned for Class 1 devicesTargets are 8- and 16-bit microcontrollers
Single-MSS windowSimplifies implementationBy default, only enough memory for a single TCP connectionSimilar to uIP, but:Memory allocated can be increased to support multiple parallel connectionsProvides independent buffer for each connectionRetransmission handled by TCP
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Slide8Updates in -02 (IV/V)7.4. OpenWSNMostly equivalent to uIP implementationOnly supports minimum functionalityE.g. does not perform retransmissions
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Slide9Updates in -03 (V/V)Annex
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More details welcome!
Slide10WG adoption ?
IETF 99 – Prague, July 201710