Network Communications Technology

Chapter 19Internet Architecture and TCP/IP

Connecting a Network to the Internet

Token Ring

Internal Gateway

Ethernet

InternetExternalGateway

Figure 19.1

NSFNET Backbone (1993)

Figure 19.2

GTE Internet Backbone (2000)

Figure 19.3:

TCP/IP Reference Model

SMTP FTP SNMPTelnet HTTP TFTP

TCP UDP

IPARP

ICMP

RARP

Network Interface Card, or PPP

ApplicationPresentationSession

Transport

Network

Data Link layerPhysical Layer

OSI Model TCP/IP Model

Application LevelTransport Level

InternetLevel

DNS

NetworkLevel

Figure 19.4

TCP/IP Protocols

Internet Protocol (IP) Packet Delivery between Networks

Internet Control Message Transmission and Message Control Protocol (ICMP) between Hosts and Gateways

Address Resolution Protocol Request Physical Address from (ARP) Source

Reverse ARP ARP Response

User Datagram Protocol Best Effort Service (Connectionless, (UDP) no Acknowledgement)

Transmission Control Protocol Reliable Service (Connection) (TCP)

Simple Network Management Diagnostics Protocol (SNMP)

Table 19.1

TCP/IP Application Level

• Simple Mail Transfer Protocol (SMPT, Port 25)

– Send email – POP3 (port 110) for access to received email

• Telnet – Remote login (port 23)

• File Transfer Protocol (FTP, port 20,21, more)

• HTTP – Web Pages (Client/Server, port 80)

• Domain Name System (DNS)

DNS Top-Level Domain Names

More now exist

tv, etc Root

com edu net orggov int mil jp

scsu

cs math

uk

Country

ca

Figure 19.5

UDP Operation

ApplicationTFTP,RPC

UDP Protocol

IP Protocol

NetworkInterface Card

Transmission Media

Data

UDP Header Data

IP Header UDP Header Data

UDP Datagram

IP Datagram

MAC Frame Header IP Datagram FCS

Ethernet or Token Ring Format

Application layer

Transport layer

Network Layer

Data LinkLayer

Figure 19.6

UDP Packet Format

Source Port 16 bitsDefine application TFTP is port 69

Destination Port 16 bitsSpecifies Destination port on server

UDP Length 16 bitsDefine number of bytes in UDP header anddata

Check Sum 16 bitsCheck sum use for error detection of UDPheader and data

DATA

Figure 19.7

TCP OperationApplication

FTP,Telnet,SMTPHTTP

TCP Protocol

IP Protocol

NetworkInterface Card

Transmission Media

Data

TCP Header Data

IP Header TCP Header Data

IP Datagram

MACHeader

IPDatagram

Data

Ethernet or Token Ring Format

Application layer

Transport layer

Network Layer

Link Layer TCP Header

Figure 19.8

TCP Packet Format

Figure 19.9

IP Datagram Packet ProtocolIP VERSION4 bits (currentversion is 4)

Header Length 4 bitsdefine number of 32 bits

word in the header

Type of theService(TOS) 8 bitsspecifies how thedatagram should behandled

Total Lengthspecifies the length ofIP datagram includingthe header in bytes.

Identification16 bits used bydestination to identifydifferent datagramfrom one file

Flags 3 bitscurrently used the first 2 bitsDF and MF bits , DF=1 donot fragment, MF=1 Morefragment is coming

Fragment Offset 13 bitscontains the offset of the fragmentedfrom the beginning of the originaldatagram

Time to Live TTL8 bits specifiesnumber of routers thedatagram can pass

Protocol 8 bitsspecifies the protocol whichdata belongs to such asTCP,UDP,ICMP

Header Checksum 16 bitsthe 16 bit one’s complement sum of theheader

Source IP Address 32 bits IP address of sending machine Destination IP address 32 bits IP address of receiving information Options if Any Padding Data

Figure 19.10

ARP Packet Format

Hardware Type 16 bits Protocol Type 16 bitsHLEN Hardware address Length 8 bits PLEN IP address Length 8 bits

Operation Code 16 bits ARP Request =1 ARP Response =2 RARP Request=3 RARP response =4

Sender Hardware Address48 bits

Sender IP Address32 bits

Target Hardware Address48 bits

Target IP Address32 bits

Figure 19.11

ARP / RARP

32 bit Internet Address

AR

P

RA

RP

48-bit Ethernet Address

Figure 19.12:

IPv4

MAC

A Network

Figure: 19.13

Token Ring

ExternalGateway

InternalGateway

129.47.3.1 129.47.3.3

129.47.3.2

129.47.3.5129.47.3.6

129.47.3.7

129.47.3.4

BiologyDepartment

129.47.3

Computer ScienceDepartment

129.47.1.2

129.47.1.3129.47.1.5 129.47.1.1

129.47.1.4129.47.1

129.47.2.1

129.47.2.2

129.47.2.3

129.47.2.4

129.47.2.5

129.47.2

MathematicsDepartment

IPv4 Addresses

• Class A – 1.0.0.0 to 126.255.255.255– 126 large organizations (all gone)

• Class B – 128.0.0.0 to 191.255.255.255 – 214 networks each with 216 hosts

• Class C – 192.0.0.0 to 223.255.255.255– 221 small networks , 255 hosts

Address Mask

• Separates a network address from the Host address

Figure: 19.14

11111111 11111111 11111111 00000000

255 255 255 0. . .

2 bytes 1 byte 1 byte

Network ID Sub ID Host IDBinary

DottedDecimal

Point-to-Point ProtocolPacket Format

Flag7E

AddressFF

Control03

for PPP

Protocol type0021 means information is IP

datagram

Information FCS Flag7E

1 byte 1 byte 1 byte 2 bytes 0-1500 Bytes 2 bytes 1 byte

Figure 19.15

Demultiplexing Information

Figure 19.16:

IPRARP ARP

UDP

Network Interface Card

MAC Header IP TCP Interface FCS

TCP

ApplicationApplication

IP TCP if Any Information

Setting up a TCP Connection

Figure 19.17:

Source Destination

SYN = 1seq x

SYN = 1ACK x + 1Seq y

Receive andsend ACK x+1

Send data seq x +1ACK y + 1

Send ACK y +1

Receive ACK

Disconnecting a TCP Connection

Figure 19.18:

FIN = 1seq = x

send ACK x+1 send FIN seq = y

RS=1 Seq X+1

RS=1 ACK X+2

Send ACK y +1

Send FINseq = x

Source Destination

IPv6 Format

Figure 19.19:

1 4 5 8 9 32

BasicHeader

VERSION 4 bits FLOW LABLEVersion Number is 6 priority Specifies the type of the information in payload field

such as speech, video information, data

PAY LOAD LENGTH 16 bits NEXT HEADER 8 bits HOP LIMIT 8 bitsIndicates the number of bytes determines which header the function is thein payload fields follows basic IP header same as TTL for IPv4

SOURCE ADDRESS 128 bits

DESTINATION ADDRESS 128 bits

EXTENTION HEADER

PayloadMaximum size of payload is 64K bytes

IP Datagram Extension Headers

Figure 19.20:

Version Priority Flow labelPayload length Next Header 0 Hop limit Source Address

Destination Address

Next header 43 Header length Hop by Hop options

Next Header 06 Header Length

Routing Information TCP Header and data

IPv6 Unicast Address

Figure 19.21:

3 bits 5 bits 16 bits 16 bits 8bits 32 bits 48 bits

Format prefix Registry ID Provider ID Subscriber type Subscriber ID Sub-network ID Interface ID

MAC

IPv4 to IPv6 Migration

Figure 19.22a:IPv4 Imbedded in IPv6

Figure 19.22b:For Station w/o

IPv6 Support

vBNS Backbone (2000)

Figure 19.23: