1. Process-to-process delivery UDP TCP SCTP
Chapter 23. UDP and TCP
Process-to-process delivery
UDP
TCP
SCTP
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2. Types of Data Deliveries
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3. Communication Networks, KWU
Port Numbers
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4. IP Address vs. Port Numbers
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5. Port Numbers: IANA Ranges
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6. Communication Networks, KWU
Socket Address
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7. Communication Networks, KWU
Error Control at L2/L4
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8. Transport Layer Protocols
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9. Well-Known Ports used by UDP
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10. Communication Networks, KWU
UDP Datagram
UDP is a connectionless, unreliable protocol that has no flow and error control
It uses port numbers to multiplex data from the application layer
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11. Communication Networks, KWU
UDP Pseudoheader
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12. Example: Checksum Calculation
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13. Well-Known Ports used by TCP
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14. Communication Networks, KWU
Stream Delivery of TCP
TCP is a transport protocol which is
Reliable
Connection-oriented
Stream-oriented
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15. Communication Networks, KWU
Sequence Number
The bytes of data being transferred in each connection are numbered by TCP
The numbering starts with a randomly generated number
The value of the sequence number field in a segment defines the number of the first data byte contained in that segment
The value of the acknowledgment field in a segment defines the number of the next byte a party expects to receive
The acknowledgment number is cumulative
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16. Sequence Number: Example
Imagine a TCP connection is transferring a file of 6000 bytes. The first byte is numbered What are the sequence numbers for each segment if data are sent in five segments with the first four segments carrying 1000 bytes and the last segment carrying 2000 bytes?
The following shows the sequence number for each segment:
Segment 1 ==> sequence number: 10,010 (range: 10,010 to 11,009)
Segment 2 ==> sequence number: 11,010 (range: 11,010 to 12,009)
Segment 3 ==> sequence number: 12,010 (range: 12,010 to 13,009)
Segment 4 ==> sequence number: 13,010 (range: 13,010 to 14,009)
Segment 5 ==> sequence number: 14,010 (range: 14,010 to 16,009)
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17. Communication Networks, KWU
TCP Segment Format
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18. Control Field and Flags
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19. Connection Establishment: Three-Way Handshaking
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20. Communication Networks, KWU
Data Transfer
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21. Connection Termination: Three-Way Handshaking
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22. Communication Networks, KWU
Sliding Window
TCP’s sliding windows are byte-oriented
The size of window is the lesser of rwnd and cwnd
rwnd: receiver window
cwnd: congestion window
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23. Sliding Window: Example
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24. Example: Normal Operation
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25. Communication Networks, KWU
Example: Lost Segment
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26. Example: Fast Retransmission
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