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SCTP. Stream Control Transmission Protocol. Nimish Vartak CS, UMBC. SCTP - Agenda. Motivation Overview of SCTP Features of SCTP Current Implementations Comparison with other protocols. Nimish Vartak. SCTP – Motivation. IP reference model. TCP UDP.
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SCTP Stream Control Transmission Protocol Nimish Vartak CS, UMBC
SCTP - Agenda • Motivation • Overview of SCTP • Features of SCTP • Current Implementations • Comparison with other protocols Nimish Vartak
SCTP – Motivation IP reference model TCP UDP Nimish Vartak
SCTP – Motivation (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 Nimish Vartak
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 Nimish Vartak
SCTP – Overview (contd …) Message Format Nimish Vartak
SCTP – Key Features • Connection set-up • Multi-streaming • Multi-homing • Selective ACKs in Data sending • Connection shut-down Nimish Vartak
SCTP – Features (contd …) Connection setup (SYN) INIT (SYN-ACK) INIT-ACK COOKIE-ECHO COOKIE-ACK End-Point A End-Point Z Nimish Vartak
SCTP – Features (contd …) Multi-streaming Nimish Vartak
SCTP – Features (contd …) Multi-homing Internet End-Point A End-Point Z Nimish Vartak
SCTP – Features (contd …) SACK in Data sending Nimish Vartak
SCTP – Features (contd …) Connection close SHUTDOWN SHUTDOWN-ACK SHUTDOWN-CMPL End-Point A End-Point Z No Half Closed State Nimish Vartak
SCTP – Special Features • Heartbeat keep-alive mechanism • Selective acknowledgments • Security perspective • Connection based • DoS attack prevention • Data based • IPSec – under SCTP • TLS – over SCTP Nimish Vartak
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. Nimish Vartak
SCTP – Comparison • Comparison of features with TCP and UDP Nimish Vartak * Courtesy Addison Wesley
SCTP – Summary Well suited for Multimedia • Like TCP • Provides connection establishment • Ensures Reliability • Provisions for ordered and un-ordered data • Provides Congestion Control • In addition to TCP features • Provides multi-homing • Provides multi-streaming • Has security features Nimish Vartak
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
SCTP Thank You. Nimish Vartak