Stream Control Transmission Protocol (SCTP) - Introduction

Stream Control Transmission Protocol (SCTP)

LAILI AIDI Presented as part of candidacy at Employer_X

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Laili Aidi – Candidacy at Employer_X Jakarta, June 12, 2013

Transport layer is responsible for process-‐to-‐process delivery.—the delivery of a packet, part of a message, from one process to another. Two processes communicate in a client/server relaKonship.

Data Delivery:

Transport Layer

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Jakarta, June 12, 2013

Port Numbers

Laili Aidi – Candidacy at Employer_X

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IP Address and Port Numbers

Socket Address


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New Transport Protocols

Many applicaKons need reliable message delivery – use TCP stream TCP provides both strict-‐ordering and reliability – many may not need both Need new protocol to reduce user-‐perceived latency and improve throughput


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What is SCTP SCTP is a message-‐oriented, reliable protocol (RFC 2960)

On top of a connectionless packet network Perform beXer in the presence of losses: no strictly ordered delivery Designed for new Internet applicaKons: ISDN over IP (IUA), SS7 signaling (M2UA, M3UA), Media gateway control (H.248), IP Telephony (H323, SIP), etc

MulK-‐homing support MulK-‐stream support

Unordered data delivery opKon

Reliable data transfer with SACK Flow Control CongesKon control Message fragmentaKon

Reliable data transfer with SACK Flow Control CongesKon control Message fragmentaKon


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Multi-Homing

Two fundamental concepts in SCTP: -‐ Endpoints (communicaKng parKes) -‐ AssociaKons (communicaKon relaKonships) SCTP associaKon allows mulKple IP addresses for each end point. This can be represented as a pair of SCTP endpoints:

-‐ assoc = { [10.1.61.11 : 2223], [161.10.8.221, 120.1.1.5 : 80]}

160.15.82.20

161.10.8.221


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Multi-Streams

SCTP associaKon can involve mulKple streams. Reduces unnecessary head-‐of-‐line blocking


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SCTP Packet

TCP has segments; SCTP has packets. Data chunks are identified by 3items: - TSN: cumulative number defines the association - SI: defines the stream - SSN: defines the chunk in a stream Control informaKon & data informaKon are carried in separate chunks.


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SCTP Packet

Control informaKon and data informaKon are carried in separate chunks


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Handshake

SCTP uses a four-‐way handshake to set up an associaKon -‐ Cookie to defense against TCP SYN-‐ aXack


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Simple Data Transfer Only DATA chunks consume TSNs; DATA chunks are the only chunks that are acknowledged. Acknowledgment defines the cumulaKve TSN, The TSN of the last data chunk received in order.


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Simple Data Transfer

Associa<on Termina<on Acknowledgment defines the cumulaKve TSN, The TSN of the last data chunk received in order.


Thank You

References: N. Gupta, S. Kumar, R. Rajamani, “SCTP v/s TCP – A Comparison of Transport Protocols for Web Traffic” Cisco, “A detailed overview of the protocol and a examinaKon of the socket API” Forouzan, “Process-‐to-‐Process Delivery: UDP, TCP, and SCTP”, Chapter 16 and 23 Karl-‐Johan Grinnemo, “Advanced Internetworking, Transport Layer"

Stream Control Transmission Protocol (SCTP) - Introduction

Technology

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