PART FIVE INTERNETWORK PROTOCOLS

1
PART FIVEINTERNETWORK PROTOCOLS
2
?????
??A
??B
???
????
???
?? 1
?? 2
?? 3
??????
??????
?????
????????????,???????????????,???????????????,?????
???????????
3
??????

• ??????????????,???????????,??????????
• ????
• ???????
• ???????????????????
• ????????,?????????????

4
????, ???????

• ???????
• Internet???
• ?????
• ????
• Internet????
• TCP/IP?????

5
???????

• ??????????????????
• ???????????????
• ????????????????????????????????????

6
??(1960s)

• 1961UCLA?Leonard Kleinrock???????????????
• 1962ARPA???????????
• 1965 Larry Roberts???????????????,?Lincoln
  Labs(???MIT????)?SDC?Q32?
• 1966-67ARPAnet???????
• 1968 BBN?Bob Karn???????????Interface Message
  Processor(IMP),????????????

7
??(1960s)

• 1969???RFC???
• 1970ARPAnet???????10????
• 1972Email,ftp???
• 1973Xerox?Bob Metcalfe???????
• 1974Vint Cerf Kahn???????TCP,ARPAnet?????????
• 1977-1978TCP???TCP?IP?
• 1980-1983ARPAnet????ARPAnet?MILNET,??????????????
  ?NSF???CSNET???????????????

8
??(1960s)

• 1983 UC Berkeley?BBN?TCP/IP????UNIX 4.2 BSD?
  Berkeley???????????API?
• 1985-1987????????NFS??????????????NFSnet???ARPAne
  t?
• 1987-1990????????Internet?EBONE(??)?NFSnet???
  Van Jacobson???TCP????????
• 1990-1993 Van Jacobson?IETF??????IPv6?????? Marc
  Andresson ??????Mosaic????

9
??????????

• 1993-??Internet????????NFSnet????ATM??????????Int
  ernet???????Internet???????????????????????ISPs,??
  ??,????,?????????????????

10
Internet?????

• IABInternet???????
• IAB??TCP/IP??????????????????????,????????TCP/IP?
  ???????????????
• IETFInternet???
• IETF?????????????

11
IPX?????
Novell NetWare Protocols
TCP/IP
OSI
NetWare
12
Internetworking Terms (1)

• Communication Network
• ?????????????????????.
• Internet
• ?????/??????????????.
• Intranet
• ??????????,???????Internet??(?WWW)?
• End System (ES)
• ?????????????????,??????????????.

13
Internetworking Terms (2)

• Intermediate System (IS)
• ?????????????,???????????????????.
• Bridge
• ??????,???????,?????OSI????2?.
• Router
• ??????,????????????.
• ?????????????????????????????????OSI??3?

14
Internetworking

• Requirement
• Link between network
• Routing and delivery of data between processes on
  different networks
• Accounting service
• Provide Services

15
Services

• Different addressing schemes
• Different maximum packet size
• Different network access mechanism
• Different timeouts
• Error recovery
• Status reporting
• Routing techniques
• User access control
• Connection or connectionless

16
Connection Oriented IS Functions

• Relaying
• Routing
• Connection oriented not often used
• (IP dominant)

17
Connectionless Internetworking

• A connectionless advantages
• Flexible internet facility
• Highly robust internet service
• Best for connectionless transport protocols
  internet service.
• No unnecessary overhead
• ShortageUnreliable
• Not guaranteed delivery
• Not guaranteed order of delivery, packets can
  take different routes
• Reliability is responsibility of next layer up
  (e.g. TCP)

18
Connectionless Operation

• ???????????????
• ???????????????
• ??DTE??????????????
• ? internet protocol(IP)
• Internet Protocol
• ? ARPANET???????
• RFC 791
• ??????????????

19
Internet Protocol Operation
LAN1
LAN2
X.25 packet- Switched WAN
WAN
Router (X)
Router (Y)
End system (A)
End system (B)

TCP
IP
LLC
MAC
Physical

TCP
IP
LLC
MAC
Physical
IP IP
X.25-3 LLC
X.25-2 MAC
Physical Physical
IP IP
LLC X.25-3
MAC X.25-2
Physical Physical
t1 t6 t2 t5 t3 t4
t7 t12 t8 t11 t9
t10
t1 t6 t2 t5 t3 t4
20
Internet Protocol Operation

TCP
IP
LLC
MAC
Physical

TCP
IP
LLC
MAC
Physical
IP IP
X.25-3 LLC
X.25-2 MAC
Physical Physical
IP IP
LLC X.25-3
MAC X.25-2
Physical Physical
t1 t6 t2 t5 t3 t4
t7 t12 t8 t11 t9
t10
t1 t6 t2 t5 t3 t4
TCP-H TCP header MACi-T MAC trailer IP-H
IP header XP-H X.25 packet header LLCiH
LLC header XL-H X.25 link
header MACi-HMAC header XL-T X.25 link
trailer
21
Internetworking

• Design issues
• Routing
• Datagram lifetime
• Fragmentation and reassemble
• Error control
• Flow control

22
Routing

• ???????????????????
• ????????????????
• ?? ???????
• ?? ??,??????????
• Source routing
• ??????????????????
• ???
• ???
• Route recording
• ???????

23
The Internet as a Network
Routing
(a) Packet-switching network architecture
N1
R3
P
R1
P
P
N2
P
S1
S2
N3
P
P
P
P
R2
P
(b) Internetwork architecture
24
Datagram Lifetime

• ???????????
• ??????
• ???????????????????
• ????????
• IP?????????
• ???????,???????
• ???? ???????????1
• ???? ???????????????????????

25
Fragmentation and Reassembly

• ?????????????
• ????
• ????
• ??????????,???????
• ????
• ??????????????????
• ???????????????
• ????????

26
IP Fragmentation

• IP???,?????????
• ???????
• Data Unit Identifier (ID)
• ??????????????
• ??????
• ??????????? (? TCP)
• ??????????
• Data length ??????,????
• Offset(???)
• ????????????
• 64 bits (8 octets)????
• More flag(????)
• ????????????

27
Fragmentation Example
Header
Header
Header
Data
Data
Data
Second fragment Data length 196 octets Segment
offset 26(64-bit units) More 0
First fragment Data length208 octets Segment
offset 0 More 1
Original datagram Data length 404 octets Segment
offset 0 More 0
28
Dealing with Failure

• ?????????????
• ??????????
• ????
• ???????????
• ????????????,???????
• ???????? (time to live in IP)
• ???????,????????

29
Error Control

• ?????????????????
• ????????,??????????????(??????)?????????????,?????
  ??????
• ?????????
• ??????
• ?????????FCS??

30
Flow Control

• ???????????????????
• ???????????
• ????????????
• ???????
• ?. ICMP

31
Internet Protocol (IP)

• TCP/IP?????,?????????????
• ??????
• ??????(? TCP),??????????
• ??????????

32
IP???(IP Datagrams)

• IP???????,????IP????????
• ??????????????????
• ?????????????????,??????????,??????

33
IP Services

• Primitives
• ????????
• ????????????
• ??????
• ??(Send)
• ???????????
• ??(Deliver)
• ???????????
• Parameters
• ???????????

34
IP Service Primitives and Parameters
Send Source address Destination
address Protocol Type of service
indicators Identification Dont-fragment
identifier Time to live Data length Option
data Data
Deliver Source address Destination
address Protocol Type of service
indicators Data length Option data Data
35
Parameters (1)

• Source address
• Destination address
• Protocol
• ?????? ?TCP
• Type of Service Indicators(??????)
• ???????????????????????????????????
• Identification(???)
• ?????????????????????,????????????????????????????
  ??(?????)

36
Parameters (2)

• Dont fragment indicator
• ?????????(?????)
• Time to live
• (?????)
• Data length
• Option data
• ?IP???????
• User data

37
IP Service Quality Options

• Precedence(???)
• ??????????????8??IP????????????????????
• Reliability(???)
• ????????????????????????????????
• Delay(??)
• ???????????????????????????
• Throughput(???)
• ????????????????????????

38
IP Options

• Security
• ??????????????.
• Source routing
• ??????????,??????????????????????????????????
• Routing recording
• ???????????????.
• Stream identification
• ??????????????????????????? (???)????????
• Timestamping(???)
• ?IP??????????????????????????????(ms)?

39
IPv4 Header
Bit 0 4 8
16 19
31
20 octets
40
IP ???

• ???(Version)
• IP ????????IPv4 ? IPv6,?????? 4
• ??????(HL)??????(Total Length)
• HL(4bit)??? 32bit ?????? IP ??????
• ????? IP ???(????)??? 20 ??,HL 5
• TL(16bit)??????? IP ??????
• ??? IP ????? ?????
• TL ????????(? IP ???????)? 65535 ??
• ????(PROTOCOL)
• 8 ???,???????????????????
• ????????????
• TCP 6 UDP 17 ICMP 1 OSPF 89

41
IP ???

• ????(Identification)
• ??????? IP ???,????? IP ????????????,?????????????
  ??
• ????(TOS Type Of Service)

42
IP ???

• ????(TTL Time To Live,1 byte)
• ???? IP ????????????
• ????? TTL ?????????????????????? TTL 0
  ?,????????
• TTL ????????????(? hop ???)
• ??????????????? IP ??
• ????????????? IP ??
• ???????(2 byte)
• ???? IP ??? ????,???????????
• ????????????????? 16 ?????,????????????????0?

43
IP ??

• ???? IP ????????
• IP ?????????????
• ???(source route)??
• ????(record route)??
• ???(time stamp)??
• IP ??????????????????
• ?????, IP ??????

44
IP ????

• IP ?????????????????
• ??(Encapsulation) ? IP ????????????
• ??????????????
• ?????????

• ??????(MTU - maximum transfer unit)
• ????????????????????,?????????????????????? MTU
  ???
• ????????,? MTU ??????????????,?????????

45
IP????(fragmentation)

• ?? ?? MTU ????????????????
• ID(Identification)????????,?????????
• MF(More Fragment,Flags ??? Bit 0)MF1 ????????
• FO(Fragment Offset)???????????????????

46
IP??????

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

????
??
47
?????

• ????(reassembly)???????
• ?????????????????

• ????
• ??????? MF1 ????,????????
• ??? MF0 ????,???? IP ?????
• ????? ?????? ????????
• ????????????????????,?????????????? IP
  ??,????????????,????????????
• ????????,????????????????????????????,???????????
  ??????,????????????

??
??
48
IP??

• IP????????,??????????????(?????????)??????????
• ?????????????????,???????????
• IP???????(??????)
• 32bits
• ?????????
• ?????????????
• IP????????

49
IP Address Formats
Class A
Network address 00000000-01111110,0-126,
01111111 reserved
Class B
Network address 10000000-10111111,128-191 ,214
16348
Class C
Network address 11000000-11011111,192-223,221
2097152
Class D
Network address 11100000-11101111,224-239
Class E
50
IP???????
Class
A
0
NetID
HostID
B
10
NetID
HostID
C
110
NetID
HostID
D
1110
Multicast Address
8 bits
8 bits
8 bits
8 bits
51
IP???????

• A?????127?????????????
• ???????8?????255,??255??????
• ???????8?????0,0??????????,????
• ???????????1,?1???????
• ???????????0,?0?????????

52

• ????????
• 10.0.0.0 ---10.255.255.255(1?A???)
• 172.16.0.0 --- 172.31.255.255 (16????B???)
• 192.168.0.0 --- 192.168.255.255(256????C???)?

53

• A?
• 128????
• ????????????

• B?
• ????????
• ?????????????

• C?
• ?????????
• ??????????????

54
???????

• ??????????????????????
• ???????????????
• ???????????????
• IP????????????
• 1.2.3.4
• 00000001 00000010 00000011 00000100
• 202.118.66.5
• 11001010 01110110 01000010 00000101
• ???

55
IP???????

• IP??????????1?
• IP???????????,????????????
• ??????0?IP????????,???????

56
????

• ????????????????????????
• ?????????????????
• ??????,???????A?B?C??????????
• ????????IP????????
• ???????????????????????????,???????????????A?B?C??
  ??

NetID
SubnetID
HostID
57
IP??

• ?????A?B?C???????
• ????????????????????????
• ??????????????????
• ????????????????????????????

58
??
router
Subnet 1 128.213.1.x
Subnet 2 128.213.2.x
Subnet 3 128.213.3.x
59
????

• ????????
• ??????????1?
• ?????????????????

60
????

• TCP/IP???????????????????????????
• ?????????32????,????????????????1,0?????????????

61
????

• ???????

??
??
A?
11111111 00000000 00000000 00000000
255 . 0 . 0 .
0
??
??
B?
11111111 11111111 00000000 00000000
255 . 255 . 0
. 0
??
??
C?
11111111 11111111 11111111 00000000
255 . 255 . 255
. 0
62
??IP??Subnet Network Number

• Typical Subnet Mask Pattern

Decimal Binary
0 0000 0000
128 1000 0000
192 1100 0000
224 1110 0000
240 1111 0000
248 1111 1000
252 1111 1100
254 1111 1110
255 1111 1111
63
Example of Subnetworking
Net ID/subnet ID192.228.17.32/27 Subnet number1
LAN X
A
B
IP address192.228.17.33 Host number1
IP address192.228.17.57 Host munber25
R1
Net ID/subnet ID192.228.17.64/27 Subnet number2
LAN Y
C
R2
IP address192.228.17.65 Host number1
LAN Z
Net ID/subnet ID192.228.17.96/27 Subnet number3
D
IP address192.228.17.97 Host number1
64
IP Addresses and Subnet Masks
Dotted decimal and binary representations of IP
address and subnet masks
Binary Representation Dotted Decimal
IP address 11000000.11100100.00010001.00111001 192.228.17.57
Subnet mask 11111111.11111111.11111111.11100000 255.255.255.224
Bitwise AND of address mask (resultant network/subnet number) 11000000.11100100.00010001.00100000 192.228.17.32
Subnet number 11000000.11100100.00010001.001 1
Host number 00000000.00000000.00000000.00011001 25
65
IP Addresses and Subnet Masks
Default subnet masks
Binary Representation Dotted Decimal
Class A default mask 11111111.00000000.00000000.00000000 255.0.0.0
Example Class A mask 11111111.11000000.00000000.00000000 255.192.0.0
Class B default mask 11111111.11111111.00000000.00000000 255.255.0.0
Example Class B mask 11111111.11111111.11111000.00000000 255.255.248.0
Class C default mask 11111111.11111111.11111111.00000000 255.255.255.0
Example Class C mask 11111111.11111111.11111111.11111100 255.255.255.252
66
??

• ????????????(?C???)????????????????????????16?C???
  ??
• IP????202.112.96.1?202.112.111.254
• ?????255.255.240.0
• ?????202.112.111.255?
• ?202.112.96.4?202.112.100.83???????(??)??

67
??????CIDR

• CIDR(Classless Inter-Domain Routing)???A?B?C??????
  ,????????
• ?IP???
• CIDR???????,???????
• CIDR??IP??????????(IP??
• )??????
• CIDR???????????

68
CIDR??

• 192.168.0.0/16????192.168.0.0
• ?192.168.0.1192.168.255.254
• 10.33.11.0/24????10.33.11.0
• ?10.33.0.1 10.33.0.254

69
ICMP(Internet Control Message Protocol)

• ICMP?????????????
• ICMP??IP????????
• ICMP?????IP????,???????????
• ICMP??????????,??????????????IP??,??????????64bit?

70
ICMP ??

• ICMP ???
• ????
• ??
• ????(??/????)
• ICMP ?????

ICMP ??
IP ?
IP ???
IP ??
PROTOCOL 1 (ICMP)

• ICMP ????? IP ?

71
ICMP????

• Echo Request
• Echo Response
• Destination Unreachable
• Redirect
• Time Exceeded
• Redirect (route change)
• there are more ...

72
Internet Control Message Protocol
Message Purpose
Destinaiton Unreachable ?????????????????????
Time Exceeded ?????????????,????
Source Quench (???) ????????????????,??? ???????????
Redirect ????????????,?????????????????????
Echo(??) ????Ping????????
73
Internet Control Message Protocol
Parameter Problem ?????????
Timestamp ??????????????
Address Mask request/reply ????????????????????
Router Advertisement and Selection(????????) ???????????????????????
74
Internet Control Message Protocol
IP
Type
Code
Checksum
Variable- Depends on Type And code
ICMP
ICMP header formats
75
ICMP ???
76
ICMP ????

• ???????????? -gt ????

• ??????? TYPE 3

• ???? TYPE 11

• ????? TYPE 12

• ICMP ???????????
• ICMP ????????????,????? IP ????????,???????????
• ICMP ?????????,??????????????????????????
• ???????????????

77
????? ICMP ?????

• ???(Source Quench)
• ?????????? IP ?????????????
• ????????
• ???????,?????? ICMP ?????
• ?????????????????????
• ?????,?????????????????
• ????????

78
????? ICMP ?????

• ??????????? ICMP ?????

• ????,??????/?????????
• ?????????????????????????????????????
• ????? ICMP ?????????????

• ICMP ?????
• ???????????????????????
• ????????????????????,????????????,???????????,???
  ?????????
• ??????????????????????

79
ICMP ???/????

• ??(Echo)??/?? ping(TYPE 8 / 0)

• ????????(TYPE 13 / 14)

• ?????????(TYPE 17 / 18)

80
ICMP Message Formats
0 8 16
31
0 8 16
31
Type Code Checksum
Pointer Unused Unused
IP header64 bits of original datagram IP header64 bits of original datagram IP header64 bits of original datagram
Type Code Checksum
Unused Unused Unused
IP header64 bits of original datagram IP header64 bits of original datagram IP header64 bits of original datagram
(b) Parameter problem
(a) Destination unreachabletime exceeded source
quench
0 8 16
31
0 8 16
31
Type Code Checksum
Identifier Identifier Sequence number
Optional data Optional data Optional data
Type Code Checksum
Identifier Identifier Sequence number
IP header64 bits of original datagram IP header64 bits of original datagram IP header64 bits of original datagram
(c) Redirect
(d) Echo,echo reply
81
ICMP Message Formats
0 8 16
31
0 8 16
31
Type Code Checksum
Identifier Identifier Sequence number
Originate timestamp Originate timestamp Originate timestamp
Receive timestamp Receive timestamp Receive timestamp
Transmit timestamp Transmit timestamp Transmit timestamp
Type Code Checksum
Identifier Identifier Sequence number
Originate timestamp Originate timestamp Originate timestamp
(f)Timestamp reply
(e)Timestamp
(f)Timestamp reply
0 8 16
31
0 8 16
31
Type Code Checksum
Identifier Identifier Sequence number
Address mask Address mask Address mask
Type Code Checksum
Identifier Identifier Sequence number
(g) Address mask request
(h) Address mask reply
82
ICMP Destination Unreachable Message

• Network unreachable
• Host unreachable
• Cant fragment
• Protocol unavailable
• Port unavailable

83
ICMP Destination Unreachable Message
10.1.1.0/24
10.1.2.0/24
A
B
10.1.3.0/24
Web
Fred
10.1.2.14
84
ICMP Destination Unreachable Message

• network unreachableif router A havent a route
  to 10.1.2.0/24. A will send an unreachable with
  network unreachable code to Fred.
• host unreachableif web is down, router B will
  not get ARP reply from web. B will send an
  unreachable with host unreachable code.

85
ICMP Destination Unreachable Message

• cant fragmentif router A or B needed to
  fragment packet, but the do not fragment bit was
  set in the IP header, it would send an
  unreachable with the cant fragment value in the
  code field.
• protocol unavailable
• port unavailable

86
ICMP Redirect
2
Redirect
3
1
87
IPv4??

• ??????
• ????????????????
• ??????
• ?IP????????
• ???IP??

88
IPv6

• ???????
• ???????
• ??????
• ????????
• ??????

89

• Extension headers
• Hop-by-Hop Option header??????????????
• Routing header????IPv4??????????
• Fragment header?????????
• Authentication header???????????
• Encapsulating Security Payload header??????
• Destination Options header???????????????

90
IPv6 Packet with Extension Headers(Containing a
TCP Segment)
Octets 40 Varible Varible 8 Varible 20(
optional variable part) Varible
IPv6 header
Hop-by-Hop Options header
Routing header
Fragment header
Destination Options header
TCP header
Application Data
Next header field
91
IPv6 Header
Bit 0 4
12 16 24
31
Version Traffic Class Flow Label
Payload Length Next Header Hop Limit
Sourece Address
Destination Address
1032 bits 40 octets
92
IPv6 Header

• ?????(Traffic Class)
• ?????????????,?????????????????????IPv6???
• ?IPv6?????????????????????????
• ??????????????????,???????????????????????????????
  ?????????
• ????????????????????????????????????

93
IPv6 Header

• ???(Flow Label)
• ???????????????????
• ???????(?????),?????
• ????????????????????
• ????????20bit??????????
• ???????

94
???????

1. ??????????????????????????????0,??????????,???????
   ????
2. ??????????????????????????????????????????????(???
   ?)???????(????)
3. ??????????????,?1?220-1?????,?????????????????????
   0???????????????

95
IPv6??

• ??128bit
• ??????????????
• ????????????
• ???????????????????????
• ????
• ??(Unicast )
• ??(Multicast)
• ????(Anycast)??????????????????????????????(?????
  ?????)??????????????????

96
IPv6 Extension Headers
0 8 16
31
One or more options
Next Header Hdr Ext Len
0 8 16
24 31
Next Header Hdr Ext Len 0 Segments left
Reserved
Address1
Address2
(a) Hop-by-Hop Options header Destination
Options header
0 8 16
29 31
Next Header Reserved Fragment Offset Res M
Identification
(b) Fragment header



0 8 16
31
Next Header Hdr Ext Len Routing type Segments
left Type-specific data
Addressn
(d) Type 0 routing header
(c) Generic routing header
97
??????

• Next Header???????????????
• Header Extension Length?64bit???,?????64bit
• Option??????????????????????????5??????????????
• ??2?????????????????????????????3????????????????
  ???????????????(0?1?)?
• ???????????????????

98

• ?????(Jumbo Payload)
• ???????????65535B?IPv6??,????????32bit,????40?B??
  ????????,IPv6??????????????0,????????
• ?????(Router Alert)
• ???????????????????????,????????????????????

99
????

• Next Header8b
• Reserved8b
• Fragment Offset13b
• Res2b
• M Flag1b
• Identification32bit

100
????

• Next Header
• Header Extension Length?64bit???,????64bit?
• Routing Type???????????????????????,??????????
• Segment Left???????

101
??????

• 0?????????????IPv6????
• ????????,???????????
• ??????????,IPv6????????
• ????????????????????
• ??????????,?????????
• ???,????????????????
• ??IPv6??,??????????????
• ????

102
??????

• ????????,?????????

103
Multicast

• ???????????????????????
• ??????????????????????
• ????????
• ??
• ???
• ????
• ???
• ?????
• ?????

104
N2
Router A
2
L2
2
B
2
L1
2
L3
3
3
D
2
4
1
N3
L4
L5
1
C
N1
4
2
6
Group member
Multicast server
N4
6
F
E
6
2
N6
1
1
N5
Group member
Group member
Example Configuration
105
Traffic Generated by Various Multicasting
Strategies
Broadcast Multiple Unicast Multicast
S-gtN2 S-gtN3 S-gtN5 S-gtN6 Total S-gtN3 S-gtN5 S-gtN6 Total
1 1 1 1 4 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 2 1 1 1 3 1 1 1 1 2 1 1 1 1 1 1 1 1 2 1 1 2 1 1 1 1
2 3 4 4 13 3 4 4 11 8
N1 N2 N3 N4 N5 N6 L1 L2 L3 L4 L5
Total
106
????

1. ??????????????????????????
2. ??????????????
3. ????????????? ????????????

107
(a) Spanning tree from source to multicast group
(b) Packets generated for multicast transmission
Multicast Transmission Example
108
?????

1. ??????????????
2. ?????????IP?????????????????????
3. ??????IP??????????????
4. ??????????????????????
5. ?????????????????????????????????
6. ?????????????????????????
7. ????????????????????????????

109
RC
L5
N4
RB
RE
RF
N5
N6
N3
Spanning Tree from Router C to Multicast Group
110
IGMP(Internet Group Management Protocol)
??????????????????????????????????????
IGMP Message Format
111
IGMP??

• ???????????????IGMP??,????????????????????????????
  ????????????????????????????????IP????,?????????
• ??????????IGMP????,???????????????,???????????????
  ??????????????
• ???????????????????,?????????????????????????,????
  ?????????????,????????????????????,???????????????
  ???????????

112
Internet?????
IAB??????
113
Internet?????

• InterNICInternet??????
• ???????,RFC???
• RFCInternet Request For Comments
• ????, Internet??(??)
• ??
• RFCshttp//www.faqs.org/rfcs
• Internet Draftshttp//www.ietf.org/

114
????(Internetworking)

• ????????
• ???????????????????????????Douglas Comer
• ???????
• ??????????,??????????????????????
• ???????????????,???????
• ??????????????????????,????????????????????????
• ??????????????,????????????
• ???????????????????????????????,??????????????

115
Internetworking Protocols in Context
MIME
BGP
FTP
HTTP
SMTP
TELNET
SNMP
UDP
TCP
ICMP
IGMP
OSPF
RSVP
IP
116
Routing Protocols

• Routing information(??????)
• Routing algorithms(??????)
• Autonomous system(????)
• ????????,??????????????.
• ?????????????????.
• ??????,??????????.
• Interior router protocol (IRP,???????)
• exterior router protocol (ERP,???????)

117
Application of Exterior and Interior Routing
Protocols

Subnetwork 1.2
Subnetwork 1.2
R6
R2
R3
R5
Subnetwork 2.2
R7
Subnetwork 1.1
Subnetwork 1.3
R8
Subnetwork 2.4
R1
R4
Subnetwork 2.3
Subnetwork 1.4
Autonomous system 2
Autonomous system 1
Interior router protocol
Exterior router protocol

118
Border Gateway Protocol (BGP)

• BGP(??????)??????????TCP/IP???????,???????????????
  ?????????????????????????,?????????????(Gateway)?
• Functional procedures of BGP
• ????
• ????
• ????

119
BGP
BGP-4 Messages
Open ????????????????.
Update ??????????????/???????????
Keepalive ??????open??,???????????
Notification ????????????.
120
BGP Messages
??

• ?? ?????.
• ??????(??)
• ?? ?????.

16 2 1 1 2 2 4 1 ??
??
??
??
??????
????
??
16 2 1
BGP???
??
??????
??
????
Keepalive massage
Open massage
121
BGP Messages
??
16 2 1 2 variable 2 variable variab
le
??
??
16 2 1 1 1 variable
??
????????
??
??
????
????
?????
????????
??
????
Notification massage
???????
Update massage
122
Open

• ???????,??????????????TCP??,????Open??,???????????
  ????????IP?????????????????????????,???????????,??
  ???????????????????????????????Keepalive?Update???
  ?????????

123
BGP Messages

• Keepalive????,???????????
• Update ???????????
• ??????????????,???????????????????.
• ??????????????????????.

124
Path attributes field

• Origin???????????????? ??
• AS_Path???????????
• Next_Hop??????IP??
• Multi_Exit_Disc??????????????
• Local_Pref???????????????????????????
• Atomic_Aggregate, Aggregator????????

125
Notification

• Message header error
• Open message error
• Update message error
• Hold timer expired
• Finite state machine error???????,??????????
• Cease

126
RIP ( Routing Information Protocol)

• Distance vector algorithm
• Included in BSD-UNIX Distribution in 1982
• Distance metric of hops (max 15 hops)
• why?
• Distance vectors exchanged among neighbors every
  30 sec via Response Message (also called
  advertisement)
• Each advertisement list of up to 25 destination
  nets within AS

127
RIP Example
A finds that z isreachable via C
X
W
Y
A
D
B
4 hops to net z
Z
C
Destination Network Next Router Num. of
hops to dest. w A 2 y B 2 z B
7 x -- 1 . . ....
A
5
Routing table in D
128
OSPF (Open Shortest Path First)

• open publicly available
• Uses Link State algorithm
• LS packet dissemination(??)
• Topology map at each node
• Route computation using Dijkstras algorithm
• OSPF advertisement carries one entry per neighbor
  router
• Advertisements disseminated to entire AS (via
  flooding)
• Carried in OSPF messages directly over IP (rather
  than TCP or UDP)

129

• ??????????
• ???
• ??,??????
• ??(transit)????????????????????
• ??(stub)???????
• ??????
• ???????????
• ??????????????????

130
A Sample Autonomous System
N13
N12
N14
N1
1
R1
3
8
8
8
N3
8
8
R4
5R
6
N12
7
1
3
R2
6
1
N2
6
2
8
1
R3
R7
6
R6
9
2
N15
7
1
N4
5
N6
1
N11
R10
3
3
1
R9
R8
2
N8
1
1
R11
4
N9
N7
1
10
2
N10
H1
R12
131
????

• ??????????????????????????????,????????
• ????????????,?????????????????
• ?????????????,?????????????
• ???????????
• ?????????AS?,??????????????????????ERP??,?????????
  ?????????????????????
• ????????????0

132
Directed Graph of Autonomous System
N13
N12
N14
R1
N1
8
3
8
1
8
N3
R4
8
R5
1
1
8
6
3
6
N12
8
7
R3
N2
R2
R6
6
2
6
9
2
N15
N1
5
7
1
1
N6
R10
3
R9
1
3
1
R11
R8
2
N9
N8
4
1
1
H1
N10
10
2
N7
R12
133
The SPF Tree for Router R6
N13
N12
N14
R1
N1
8
3
8
8
N3
R4
R5
6
1
3
6
N12
R3
R6
N2
R2
2
6
R7
9
2
N15
N1
7
1
N4
N6
R10
3
R9
3
R11
R8
N9
N8
4
1
1
H1
N10
10
2
N7
R12
134
Routing Table for R6
Destination Next Hop Distance
N1 R3 0
N2 R3 10
N3 R3 7
N4 R3 8
N6 R10 8
N7 R10 12
N8 R10 10
N9 R10 11
N10 R10 13
N11 R10 14
H1 R10 21
R5 R5 6
R7 R10 8
N12 R10 10
N13 R5 14
N14 R5 14
N15 R10 17
135
OSPF advanced features (not in RIP)

• Security ??OSPF ????? (??????)
• ????????????? (RIP?????)
• ????????????????????????????
• ???????????
• ??????????????
• ?????OSPF????

136
OSPF

• OSPF?????? 1?OSPF????LOOP- FREE(?????)?????????
  ???????(????????????)2?OSPF?????????????????????
  ????????3?????(area)?????,?????????????,?????????
  ??????,???????????????????????????????????????4??
  ????????????

137
EIGRP

• ????????????? (Enhanced Interior
• Gateway Routing Protocol)
• ???????????????,?????????????????????????,????????
  (DUAL),???????????
• EIGRP????? ??EIGRP????????????,?????????????????
  ?????Hello??????,???????Hello??????????5s?

138
EIGRP

• EIGRP??????????1. ??????????????2. ???????
• 3. ????????????4. MD5??5. ???????????6.
  ???????????????????7. ??????

139
OSPF vs EIGRP

• OSPF???1????????2????????????
• EIGRP???1. EIGRP????(AREA)???
• 2. ??EIGRP??????????????HELLO?????????,??????????
  3. EIGRP??????????????????DUAL???,???????,??????
  ,?????????,EIGRP?????????4?EIGRP?Cisco????????

140
IP????(IP routing)

• ????????????????
• ?????????????
• ???????????
• ?IP??????????,???????????????
• ?????????????????
• ???????????????
• ??????????????
• ????(routing table)???????,???????????
• ???????????????????????????

141
IP????(IP routing)

• IP????????????,???????????,?????????
• ?ARP, RARP?????????
• ???????????
• ????????,??????????????????

142
IP??(IP routing)
30.0.0.7
40.0.0.9
128.1.0.9
192.4.0.0
128.1.0.0
40.0.0.0
30.0.0.0
40.0.0.10
128.1.0.10
192.4.10.9
143
IP??(IP routing)
Router
128.10
128.211
Router
128.10.0.1
128.10.0.2
128.211.6.115
10.0.0.37
10.0.0.49
192.5.48.3
10
Router
192.5.48
144
IP????(IP routing)

• ????????
• ????????,???????????IP????,?????????IP???,????????
  ??????????????????????
• ??????????,????IP??,??????????????,???????????????
  ??????????????,IP???????????????????????????

145
IP??????????

• IP??????????????
• ????IP?????(MAC)???????????AR(Address
  Resolution)?
• ??????RAR(Reverse Address Resolution)
• ?????????IP??????????????
• ????????????????(DHCP)?
• ARP
• ??????(Address Resolution Protocol)?????IP??,?????
  ?????????
• ARP???????????????????????
• ???????????IP??????,????????????

146
ARP

• ARP???????IP????????????????????????
• ARP??????????????????????????????????

HEY - Everyone please listen! Will 128.213.1.5
please send me his/her Ethernet address
not me
Hi Red! Im 128.213.1.5, and my Ethernet address
is 87A2153502C3
147
RARP

• ????????(RARP)????????????????? ARP ????????? IP
  ??????????????????????????????(MAC)??????IP???????
  ??????,? RARP ????????????? RARP ???????? IP
  ???????????????????,RARP ??????? IP
  ?????,?????????????
• RARP ?????????????????????? LANs

148
RARP
HEY - Everyone please listen! My Ethernet
address is 22BC66170175. Does anyone know my
IP address ?
not me
Your IP address is 128.213.1.17.
149
?????????

• ????
• ??????????????????????????

• ????
• ????????????,??????????????????

150
??????

• ?????????

R1gt ip route-static ip-address mask masklen
interface-type interface-name
nexthop-address preference value reject
blackhole

• ??
• ip route-static 129.1.0.0 16 10.0.0.2
• ip route-static 129.1.0.0 255.255.0.0 10.0.0.2
• ip route-static 129.1.0.0 16 Serial 2

?????????????????(PPP?HDLC)????,?????ltinterface-n
amegt,??????ltnexthop-addressgt?
151
????????
129.1.0.0/16
Router A
Router B
S0
S0
E0
129.0.0.2
129.0.0.1

• ???? Quidway A???
• ip route-static 129.1.0.0 255.255.0.0
  10.0.0.2
• ip route-static 129.1.0.0 16 10.0.0.2
• ip route-static 129.1.0.0 16 s0

152
????
Quidway A
Quidway B
S0
10.0.0.2
10.0.0.1
S0
Network N
Public Network

• ???? Quidway A???
• ip route-static 20.0.0.0 255.0.0.0 10.0.0.2

• ???? Quidway B???
• ip route-static 20.0.0.0 255.0.0.0 10.0.0.1

????????????,??????
153
??????
154
??????????
155
??????????
1
1
A
B
RTB
RTA
2
5
5
2
C
RTC
3
3
D
RTD
(?)???????
(?)????????? ???????
(?)?????????????????????
156
??????????
????A????????
A
????????????
B
?????
?????
157
????
???????,????????????????
158
????
159
???????(?)
160
???????(?)
161
????
162
????????
163
???????????
164
???????
165
???????
166
???????
167
RIP???? (?)

• RIP????????????,??15??
• RIP??????????,?RIP-1?RIP-2?

168
RIP???
169
OSPF????

• ????????
• ?????????
• ?????
• ????????VLSM
• ??????
• ??????
• ????????
• ????
• ?????????????

170
OSPF?????????

• Router ID
• ??32bit??????,???????????,???????????
• ???
• OSPF?????89?

IP Header (Protocol 89) OSPF Packet
171
OSPF???????

• HELLO??
• ????????????
• DD??
• ??????LSDB????
• LSR??
• ???????????????LSA?
• LSU??
• ???????????LSA?
• LSAck??
• ??LSU??,?????

172
OSPF????
173
?????(Metric)

• ?????????????????????????????
• ????????????????????????????????????????,?????
  ???

174
?????(Preference)
???????????????????????????
175
Integrated Services Architecture

• Elastic traffic(?????)
• E-mail
• ??????
• ??????
• ?????
• Inelastic traffic(??????)
• Throughput???????????
• Delay?????
• Jitter(??)???????????????
• Packet loss??????????????????

176
Integrated Services Architecture

• ISA????????????????????????????IP???????????????,?
  ????????????????????
• 1?Routing algorithm
• ????????,???????,????????
• 2?Packet discard
• ????????????TCP??????????,???????

177

• ISA?????????QoS???
• Admission control(????)
• ????????
• Routing algorithm
• ????QoS??????
• Queuing discipline(????)
• ??????????
• Discard policy
• ????????????

178
Integrated Services Architecture

• ISA components
• Reservation protocol(????)
• Admission control (????)
• Management agent(????)
• Routing protocol
• Packets forwarding
• Classifier and routing selection(?????????)
• Packet scheduler(????)

179
????ISA???
??? ???
????
????
????
???? ???
???? ????
????? ????
??? ???
QoS ??
???????
180
Token Bucket Scheme
???? ??R? IP ???
???? B????
ltRTB
???? ???
?????
?????

181
ISA????

• ????
• ???????????????
• ?????????????????
• ??????
• ??????
• ??????,??????????
• ???????????????
• ????????????????
• ???????

182
Queuing Discipline

• ????FIFO,??
• ?????????????????????
• ??????,?????
• ??????????????

183
????RSVP

• ????????????????????
• ?????????????,??????
• ??????????

184
?????

• IP??????????
• IP????????????
• IP?????????
• ?218.108.89.202
• ????IP?????????
• ?????www??

185
Internet????

• ????(Domain Name System)
• ?????????IP??????????????
• ?????????,????????,????
• DNS???
• ??????
• ??
• ????
• DNS???
• DNS??
• DNS???

186
DNS?????
edu
com
org
cn
mit
Berkeley
edu
zust
187
???????

• ???????????.???????
• ????????63???
• ?????????255???
• ??
• whitehouse.gov
• bbs.dlut.edu.cn

188
??

• ?????????????????????????????
• ????????????
• ???
• edu, gov, com, net, org, mil,
• ??????????(2?????)
• ???????????
• ?????????????????????????????

189
DNS???

• ???????
• ???????????DNS???,?????????????IP????????
• ???????DNS???????zust.edu.cn?????????IP??????
• ??????????DNS???,??????????DNS????

190
DNS???

• ????????????
• ?????DNS?????????????????
• ???????????????
• DNS??
• ????????????IP????,?????DNS????????
• ????????DNS??????????DNS????

191
???????????

• ??????????????????????IP???(????????????)
• ?????????DNS????
• ????????DNS???????????IP??????
• ???????DNS???????????

192
DNS???

• DNS??????????IP?????,???????
• ??????? NS
• ?????? CNAME
• ?????? MX
• ???? HINFO

193
?DNS???

• ??????????????????(???????????)????

• ??????
• ???????????????????,??????????
• ????????????DNS??????
• ??????????????

194
?????????

• ??????A???itee.zust.edu.cn???
• A????DNS???C?????
• ??C???????itee.zust.edu.cn???,????DNS????????
• ?DNS?C????cn??DNS???D???
• C?D??,????edu.cn?DNS???E????
• C??E??,??zust.edu.cn?DNS???F????
• ??C?F????itee.zust.edu.cn????

195
DNS??

• ??????????
• ???????
• ???????