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MG0432039

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Title: TCP Author: hp20 Last modified by: hp20 Created Date: 11/5/2004 6:45:10 AM Document presentation format: Company: hp20 Other titles – PowerPoint PPT presentation

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Title: MG0432039

1
??????????????

???
MG0432039
alpinist04g_at_software.nju.edu.cn

2
????

TCP??
UDP??
?????

3
TCP??

TCPTransfer Control Protocol
??????????,???????????????????????????????????????
????TCP??????????,???????????????????

4
IPv4????
5
?????????

?????????????????????socket,bind,listen?????,?????
?(passive open)?
??????connect??????(active open),?????tcp????SYN??
(????),??????????(????)????????????????????SYN????
???,??????IP?????TCP???????TCP???
??????????SYN,??????????SYN??,????????????????????
??????????????????SYN????SYN?ACK?
??????????SYN?

6
?????????
7
?????????

??????????close,????????????(active
close)?????TCP??????FIN??,?????????
???FIN??????????(passive close)???FIN?TCP?????????
????????????????(???????????????????????),??FIN???
??????????????????????????
?????,????????????????close?????????????TCP?????FI
N?
?????FIN?????TCP(???????????)???????

8
?????????
9
TCP?????
10
TCP???????????????
11
TIME_WAIT??

???????????????MSL(maximum segment
lifetime)???,????2MSL?
??????????
????TCP?????????
???????????????
??????,??????????(???IP?????????IP????)???????

12
??????
13
TCP????

???????,????????????

14
TCP????

???????

15
TCP??????

Nagle??(RFC 896Nagle 1984)
????????
????

16
??

?????,???????????????????????????????????,????????
??41???20???IP???20???TCP???1??????

17
Nagle??

???????TCP??????????????????????,?????????????????
???????,TCP?????????,?????????????????????????????
?????????????,?????????????????????????????,?????
?????

18
TCP??????

????
????
???

19
????-1
20
????-2
21
????-3

??????????????????
???????????????????????????????????????????
??????7?8??????,????????,???????????????
????????ACK?????????????????????????????ACK?

22
????

4.2BSD???????????????2048????4.3BSD???????4096???S
unOS4.1.3?BSD/386?SVR4????4096????????????,?Solari
s2.2?4.4BSD?AIX3.2????????????,?8192?16384??

23
???(Slow Start)

????
?????????????????,?????????????????????????????
?????,?????????????????????????????????????,??????
??????????????????,???????????????????TCP???????

24
???????

???????????????????????????????????????
????????TCP????????????(??cwnd)?????????????TCP??
?,?????????1????(????????????)??????ACK,??????????
??(cwnd??????,?????????????????)??????????????????
???????????????????????,??????????????????
?????????????,????ACK?????ACK?,?????1??2,?????????
????????????ACK?,??????4????????????(2? )?
????????????????,????????????????????????????????

25
TCP??????

??
???????????
????

26
????????

TCP?????????????????????????????????????????????TC
P????????????????????????????????????,????????????
???,???????????????,????????????????????

27
???????????

Cwnd???? ssthresh?????
????
?????????ACK?,?ssthresh?????????cwnd??????????????
?cwnd?ssthresh??3????????
??????????ACK?,cwnd??1?????????1???(???cwnd????)?
??????????ACK???,??cwnd?ssthresh(??1??????)???ACK?
???????????????????1?????????,??ACk???????????????
1????ACK??????????????

28
????

?TCP??????,????????????????,TCP???????????????????
,?????????(??,???????????????????MSS)?

29
UDP??

UDP????????????????
UDP?????(connectionless)???,??UDP????????????????
UDP??????????????IP????????,???????????????

30
UDP??
31
IP??-1

????????IP??????????????MTU,?????IP????????????,??
?????????????????,?????????????????????
???IP???????,???????????????

32
IP??-2

?IP???????,??????????,?????IP??,?????????????????,
????????????????????,???IP????????????????????????
?
?????????????????????

33
ICMP?????(????)

IP??????????????????(DF?)???????1,IP????????????
????????????ICMP????(destination unreachable,
fragmentation needed but DF bit set)?????

34
?????

??IP?????????????????
?????????UDP,??????????????????????????
????????????????????
??????????????????

35
??????

??,?????????????,?????????????????????????????????
????,?????????????,???????????????
??????????????????,??????????????(IP?ARP?)???,????
???????????????????????
IP???IP?????????????????????????,???????????(?TCP?
UDP)?
??UDP???IP ???????,????????,??????????????????????
?????????,????????????ICMP?????(TCP?????????????)?
?UDP?????????,?????

36
?????
37
?????

?????
???????
???????
?????????

38
?????

????????255.255.255.255?????????????IP????????,??,
??????????????????,?????IP???????
?????,???????????????????????,????????????????

39
???????

???????????????1????A????????netid.255.255.255,??n
etid?A????????
????????????????,?????????????????

40
???????

???????????????1??????????????????????IP??????????
??
??,????????128.1.2.255????,?B???128.1??????255.255
.255.0?,????????????????????????255.255.254.0,???
?????????????

41
?????????

???????????????????????,??????????????????????????
???????????1?
??,????????255.255.255.0,??IP??128.1.255.255??????
???????????,?????????,?????????????

42
??

IP????????
????????????
????????????,?????????????????

43
?????

???28bit???????????????
???????224.0.0.0?239.255.255.255
???????????????????????????(host
group)????????????????????????????????????????????
??,???????????????????????

44
??????????????

I A N A??????????,???24 bit?0 0 0 0 5
e(??????),?????????????????0 0 0 0 5 e 0 0
0 0 0 0?0 0 0 0 5 e ff ff ff?I A N
A????????????????????????,????????????????0
1,?????I P??????????????0 1 0 0 5 e 0 0 0
0 0 0?0 1 0 0 5 e 7 f ff ff?
?????????????????2 3 b i t?I P????????,???????????
2 3 b i t????????????2 3 b i t???
??????????5 bit?????????,???????????????????????
???????????,?????????I P?????????????

45
?????
46
?????????