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SCTP

Nimish Vartak

CS, UMBC

Stream Control Transmission Protocol

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SCTP - Agenda

Motivation

Overview of SCTP

Features of SCTP Current Implementations

Comparison with other protocols

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SCTP Motivation

IP reference model

TCP UDP

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SCTPMotivation (contd )

New applications

Migration from PSTN to Packet based Internet Telephony signaling messages

Shortcomings of existing protocols

TCP

head-of-line blocking Byte-oriented, not message-oriented

Multi-homing support not built in

DoS attack prone

UDP

No Reliability

Absence of congestion control

Absence of flow control

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SCTP Overview

SCTP is a reliable transport protocol operating on top of a

connectionless packet network such as IP. RFC 2960

Has built-in support for multi-homed hosts

Is message-based conserves the message boundaries.

Classifies messages as:

sequenced delivery of user messages within multiple streams

with an option for un-ordered delivery of individual user messages

Additional security mechanisms

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SCTPOverview (contd )

Message Format

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SCTP Key Features

Connection set-up

Multi-streaming

Multi-homing Selective ACKs in Data sending

Connection shut-down

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SCTPFeatures (contd )

Connection setup(SYN) INIT

(SYN-ACK) INIT-ACK

COOKIE-ECHO

COOKIE-ACK

End-Point A End-Point Z

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SCTPFeatures (contd )

Multi-streaming

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SCTPFeatures (contd )

Multi-homing

Internet

End-Point A End-Point Z

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SCTPFeatures (contd )

SACK in Data sending

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SCTPFeatures (contd )

Connection close

SHUTDOWN

SHUTDOWN-ACK

End-Point A End-Point Z

SHUTDOWN-CMPL

No Half Closed State

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SCTP Special Features

Heartbeat keep-alive mechanism

Selective acknowledgments

Security perspective

Connection based DoS attack prevention

Data based

IPSec under SCTP

TLS over SCTP

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SCTP Implementations

Implementation Kernel Level - Highly scalable

Platforms: Linux, Solaris, FreeBSD, Unix,

Several Implementations in progress in the

The Linux Kernel SCTP User Level - Easy maintenance

Randall Stewart's reference implementation

http://www.sctp.org/

Ported to many platforms - Linux, Solaris,FreeBSD, AIX, Tru64(Compaq), Windows, etc.

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SCTP Comparison

Comparison of features with TCP and UDP

* Courtesy Addison WesleyNimish Vartak

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SCTP Summary

Well suited for Multimedia

LikeTCP

Provides connection establishment

Ensures Reliability

Provisions for ordered and un-ordered data

Provides Congestion Control

In addition toTCP features

Provides multi-homing Provides multi-streaming

Has security features

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SCTP References

Computer.org(http://www.computer.org/internet/v5n6/w6wire.htm )

IETF RFC 2960

(http://www.ietf.org/rfc/rfc2960.txt)

Stream Control Transmission Protocol (SCTP): A Reference Guide, R.Stewart and Q. Xie, Addison Wesley

IBM.com

(http://oss.software.ibm.com/linux/presentations/lwce2002/Chats/SCTP/SCTP-LWE.pdf)

Nimish Vartak

http://www.computer.org/internet/v5n6/w6wire.htmhttp://www.ietf.org/rfc/rfc2960.txthttp://oss.software.ibm.com/linux/presentations/lwce2002/Chats/SCTP/SCTP-LWE.pdfhttp://oss.software.ibm.com/linux/presentations/lwce2002/Chats/SCTP/SCTP-LWE.pdfhttp://oss.software.ibm.com/linux/presentations/lwce2002/Chats/SCTP/SCTP-LWE.pdfhttp://oss.software.ibm.com/linux/presentations/lwce2002/Chats/SCTP/SCTP-LWE.pdfhttp://www.ietf.org/rfc/rfc2960.txthttp://www.computer.org/internet/v5n6/w6wire.htm

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SCTP

Thank You.

Nimish Vartak