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TCP

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TCP Today s topics TCP Functions provided by TCP TCP s error recovery TCP s congestion control TCP performance analysis Application Layer DNS FTP, Telnet, WWW ... – PowerPoint PPT presentation

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Title: TCP


1
TCP
2
Todays topics
  • TCP
  • Functions provided by TCP
  • TCPs error recovery
  • TCPs congestion control
  • TCP performance analysis
  • Application Layer
  • DNS
  • FTP, Telnet, WWW browsing, email
  • Intranet Extranet

3
TCP is a connection for the two end hosts
A
B
Full duplex connection
TCP
TCP
  • Connectionless IP network (not aware of TCP
    connection)

4
Functions provided by TCP
  • Clocks
  • Buffer status
  • Sequencing packets
  • Duplication reminder
  • ACK generate
  • Retransmit lost packets (reliable service)
  • Adapt transmission speed (congestion control)

5
Connection established
6
TCP Sliding window
Sender side (in bytes) 17 18 19 20 21 22 23 24
25 26 27
7
TCP header
Flags URG ACK PSH RST SYN FIN
8
UDP Header
9
TCP Tunnel
If the sender launcher a new packet every time it
receives an ACK, then it will deliver data at
exactly the same rate of the bottleneck link.
10
TCP bandwidth as a function of Window Size and RTT
  • TCP BW WS/RTT

11
Delayed ACK
  • Suppose that delayed ACK is set. When does the
    receiver send ACK upon receiving a packet?
  • There is a data packet to send
  • 200ms expires
  • Receiver buffer increased by 2 segments (Thus one
    ACK is send for every other packet received)
  • Out of order packet received

12
Slow start through the use of congestion window
  • Sender wants to be conservative, I.e. not to send
    a whole window-worth data
  • At the beginning of a new connection
  • After a packet loss
  • This is called slow start, it uses a advertised
    window and congestion window.

13
TCP throughput
  • TP win/RTT, winmin (adv_win, cwnd)
  • RTT includes propagation and queueing delays
  • Bandwidth-Delay product link_rate 2propgation

14
(No Transcript)
15
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  • ?????????????????????,??????????,?????????????????
  • ?????????????????????????,???????????????????????
  • ?????????????????????????????????,???????????????
    ?????

16
????????TCP??
  • TCP??IP????????TCP??????????,?IP????
  • ?????????????,??????????????????,????????????????
    ??????????,TCP/UDP???????????
  • TCP/IP???????????????,????????,??????????????????
    ????(??256????),????????????,???????????,?????????
    ?????????????,????????
  • ?????Internet?,??????????????
  • ??,????,?????,????,?????

17
????????????????
  • ?????,??????????,??????????,??????????
  • ?????????????
  • ??????????????????,???????????????????

CR(????X)
???
CR(????X)
CC(????Y ??X)
CC(????Y ??X)
CR???? CC???? DATA??
???
DATA(??X ??Y)
???
DATA(??X ??Y)
18
?????TCP?UDP
???????Internet?
  • UDP(User Datagram Protocol)
  • ????????
  • ?????????????
  • ????,???????
  • TCP(Transport Control Protocol)
  • ???????
  • ????????????????
  • ????,?????????

19
TCP??
  • TCP???????????
  • ??????????????????????
  • TCP??????
  • 1.???????TCP???????????????,?????????????????????
    ??,?????????????????

0123456789101112131415
TCP?
???
??
20
TCP?????
  • 2. ????TCP???????????????????????,????????
  • 3. ????????????,????????????????????????????

????
1 2 3 4 5 6 7 8 9
10 11
????????
??????
21
TCP/IP?????????
??
22
?????
  • TCP/IP ?????
  • ??????

23
TCP/IP??????
  • TCP/IP???????????
  • Internet????????,????????????????????????
  • ??????
  • ?????????????????????
  • ?????????Internet?????????????
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