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S CTP

S CTP. Stream Control Transmission Protocol CH 23 Aseel Alturki. SCTP.

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S CTP

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  1. SCTP Stream Control Transmission Protocol CH 23 Aseel Alturki

  2. SCTP • Stream Control Transmission Protocol (SCTP) is a new reliable, message-oriented transport layer protocol. SCTP, however, is mostly designed for Internet applications that have recently been introduced. These new applications need a more sophisticated service than TCP can provide. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  3. SCTP SCTP is a message-oriented, reliable protocol that combines the best features of UDP and TCP. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  4. SCTP Services • 1. Process-to-process Communication • Table 23.4 Some SCTP applications Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  5. SCTP Services (Cont..) 2. Multiple Streams • Figure 23.27 Multiple-stream concept Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  6. SCTP Services (Cont..) An association in SCTP can involve multiple streams. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  7. SCTP Services (Cont..) 3. Multihoming • Figure 23.28 Multihoming concept Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  8. SCTP Services (Cont..) 4. Full-Duplex Communication 5. Connection-Oriented Service 6. Reliable Service SCTP association allows multiple IP addresses for each end. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  9. SCTP Features 1. Transmission Sequence Number In SCTP, a data chunk is numbered using a TSN. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  10. SCTP Features (Cont..) 2. Stream Identifier To distinguish between different streams, SCTP uses an SI. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  11. SCTP Features (Cont..) 3. Stream Sequence Number To distinguish between different data chunks belonging to the same stream, SCTP uses SSNs. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  12. SCTP Features (Cont..) 4. Packets TCP has segments; SCTP has packets. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  13. SCTP Features (Cont..) • Figure 23.29 Comparison between a TCP segment and an SCTP packet Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  14. SCTP Features (Cont..) In SCTP, control information and data information are carried in separate chunks. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  15. SCTP Features (Cont..) • Figure 23.30 Packet, data chunks, and streams Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  16. SCTP Features (Cont..) Data chunks are identified by three items: TSN, SI, and SSN. TSN is a cumulative number identifying the association; SI defines the stream; SSN defines the chunk in a stream. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  17. SCTP Features (Cont..) 5. Acknowledgment Number 6. Flow Control 7. Error Control 8. Congestion Control In SCTP, acknowledgment numbers are used to acknowledge only data chunks; control chunks are acknowledged by other control chunks if necessary. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  18. Packets Format • Figure 23.31 SCTP packet format Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  19. Packets Format (Cont..) In an SCTP packet, control chunks come before data chunks. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  20. Packets Format (Cont..) 1. General Header • Figure 23.32 General header Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  21. Packets Format (Cont..) 2. Chunks • Table 23.5 Chunks Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  22. An SCTP Association A connection in SCTP is called an association (to emphasize multihoming). Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  23. An SCTP Association (Cont..) 1. Association Establishment • Figure 23.33 Four-way handshaking • Cookie: To solve SYN flooding kind of attacks. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  24. An SCTP Association (Cont..) No other chunk is allowed in a packet carrying an INIT or INIT ACK chunk. A COOKIE ECHO or a COOKIE ACK chunk can carry data chunks. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  25. An SCTP Association (Cont..) 2. Data Transfer In SCTP, only DATA chunks consume TSNs; DATA chunks are the only chunks that are acknowledged. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  26. An SCTP Association (Cont..) • Figure 23.34 Simple data transfer Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  27. An SCTP Association (Cont..) The acknowledgment in SCTP defines the cumulative TSN, the TSN of the last data chunk received in order. • Multihoming Data Tranfer • Multistream Delivery • Fragmentation Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  28. An SCTP Association (Cont..) 3. Association Termination • Figure 23.35 Association termination Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  29. Flow Control In SCTP, we need to handle to units of data, the byte and the chunk. The values of rwnd and cwnd are expressed in bytes; The values of TSN and acknowledgments are expressed in chunks. Some assumptions to ease understanding: • There is never congestion in the network • The network is error-free • Data transfer is unidirectional Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  30. Flow Control (Cont..) • Figure 23.36 Flow control, receiver site Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  31. Flow Control (Cont..) • Figure 23.37 Flow control, sender site (Assumption: each chunk is 100 bytes long) Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  32. Flow Control (Cont..) • Figure 23.38 Flow control scenario Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  33. Error Control SCTP uses a SACK chunk to report the state of the receiver buffer to the sender. Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  34. Error Control(Cont..) • Figure 23.39 Error control, receiver site Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  35. Error Control (Cont..) • Figure 23.40 Error control, sender site (Assumption: each chunk is 100 bytes long) Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

  36. Error Control (Cont..) 1. Sending Data Chunks The total size of the data chunk or chunks included in the packet must not exceed rwnd – inTransit AND The total size of the frame must not exceed the MTU (Maximum Transmission Unit) size • Retransmission 2. Generation SACK Chunks Based on Data Communications and Networking, 4th Edition. by Behrouz A. Forouzan, McGraw-Hill Companies, Inc., 2007

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