SCTP : State of the Art in Research, Products, and Technical Challenges 박해윤 Shaojian Fu and Mohammed Atiquzzaman, University of Oklahoma

Contents Introduction Main Features of SCTP The State of the Art in Research Activities Available SCTP Products Implementation Considerations Issues and Challenges Conclusions 2Software Engineering Lab

Introduction Last few year Trends 3Software Engineering Lab VoIP

Introduction VoIP 의 개념 Software Engineering Lab4 SS7(Signaling System7) 이란 ? - 음성 통신의 호출 정보와 데이터 통신의 접속 정보 등을 통합 관리하기 위한 개방 신호 처리 프로토콜. - 즉, 통화설정, 요금 청구, 통화 라우팅등 일반 전화망과의 정보 교환을 수행. SS7 message Setup and teardown messages, billing information, Routing queries, and so on.

Introduction SS7 in TCP  Information carried is critical to the operation of network.  Therefore, SS7 need reliable and timely delivery. Available standard transport layer  User Datagram Protocol(UDP) - not reliable  Transmission Control Protocol(TCP) – reliable  Several deficiencies of TCP TCP’s strict byte-order delivery gives rise to head-of-line (HOL) block ing in some applications. TCP is stream-oriented instead of message-oriented. TCP does not support multihoming, which is crucial in high-availabilit y environments such as SS7 signaling transport. TCP is vulnerable to blind denial of service (DoS) attacks by SYN se gments. Software Engineering Lab5 축 SCTP 탄생

Main Features of SCTP Multihoming  Multihoming allows an association between two endpoints span across multiple IP addresses or network interface card. Software Engineering Lab6 TCP Connecting… Data2 Data1 Not Connecting… TCP 에서는 … Need Interrupt Need reconnect Need retransport

Main Features of SCTP Multihoming  Multihoming allows an association between two endpoints span across multiple IP addresses or network interface card. Software Engineering Lab7 SCTP Association… Data2 Data1 Association… Primary Not Association… SCTP 에서는 … Moltihoming Interrupt X Rapid recovery

Main Features of SCTP MultiStreaming  MultiStreaming allows data from the upper layer application to be multiplexed onto one channel (called association in SCTP). Software Engineering Lab8 TCP HOL(Head of Line) Blocking SCTP

Main Features of SCTP MultiStreaming  MultiStreaming allows data from the upper layer application to be multiplexed onto one channel (called association in SCTP). Software Engineering Lab9

Main Features of SCTP MultiStreaming  MultiStreaming allows data from the upper layer application to be multiplexed onto one channel (called association in SCTP).  HOL Block 회피 가능.  정책에 따라 전송속도 향상 가능 Software Engineering Lab10

Main Features of SCTP Congestion Control  SCTP congestion control is based on the well proven rate-adaptiv e window-based congestion control scheme of TCP. Software Engineering Lab11 TCP ClientServer Segment Ack - Basic

Main Features of SCTP Congestion Control  SCTP congestion control is based on the well proven rate-adaptiv e window-based congestion control scheme of TCP. Software Engineering Lab12 TCP ClientServer Segment Ack - Slow Start & 지수 증가 CWND = 12 Segment Ack 4 Segment - 혼잡회피 & 가산 증가 - 혼잡감지 & 지수 감소

Main Features of SCTP Congestion Control  SCTP congestion control is based on the well proven rate-adaptiv e window-based congestion control scheme of TCP. Software Engineering Lab13 TCP ClientServer Segment CWND = 4 2 번째 까지만 제대로 받았구나 번째까지 받았다고 ACK 을.. 먼가 잊어버렸구나.. 그럼 다시 보내 ! ※ SACK Option - 다 보내지 말고, 누락된 것만 보내도록, 받은 애들을 기록하자.

Main Features of SCTP Congestion Control  SCTP congestion control is based on the well proven rate-adaptiv e window-based congestion control scheme of TCP. Software Engineering Lab14 SCTP SCTP does not have an explicit fast recovery phase. SCTP allows more robust reaction in the case of multiple losses. During slow start or congestion avoidance of SCTP, the congestion window(cwnd) is increased by the number of acknowledged bytes. During congestion avoidance of SCTP, cwnd can only be increased when the full cwnd is utilized. SCTP begins after four DupACKs.

Main Features of SCTP SECURITY  Protecting Availability of Service. Software Engineering Lab15 TCP ClientServer SYN SYN, ACK ACK Data Close Half Open Open 75 초 대기 Backlog queue DoS Attack SYN Flooding 3-Way Handshake

SCTP Main Features of SCTP SECURITY  Protecting Availability of Service. Software Engineering Lab16 ClientServer INT INT ACK Cookie Cookie ECHO Cookie ACK Close Established Baking 4-Way Handshake Cookie 가 다르네.. 버려 …

Main Features of SCTP Protecting the Integrity of User-to-User Software Engineering Lab17 데이터 무결성 authentication 데이터 무결성 authentication secret service 서버 authentication 클라이언트 authentication 암호화된 메시지 전달

Main Features of SCTP Differences From TCP Software Engineering Lab18

Thank you!!!