Computer NetworksMarwan Al-Namari

Week 7

Addressing

Network Addressing

A network address consists of two parts: (i) Address of the LAN and (ii) Device or host address on that LAN

compare with a house address – street name and house number

IP addressesCurrently there are two types of Internet Protocol (IP) addresses in active use:

IP version 4 (IPv4) and IP version 6 (IPv6). IPv4 was initially deployed on 1 January 1983 and is still the most commonly used version. IPv4 addresses are 32-bit numbers often expressed as 4 octets in "dotted decimal" notation Deployment of the IPv6 protocol began in 1999.

IPv6 addresses are 128-bit numbers and are conventionally expressed using hexadecimal strings

IP addresses authorities

If you are connecting to the Internet, you will need to get a registered IP address from the agency that governs IP addresses, this was the Internet Assigned Numbers Authority (IANA)

now done by ICANN...or

from an Internet Service Provider (ISP) that has already obtained blocks of addresses from an Internet Registry

Binary CodeBinary Code Bit Values Decimal Value

000000000000000100000011000001110000111100011111001111110111111111111111

01

2+14+2+1

8+4+2+116+8+4+2+1

32+16+8+4+2+164+32+16+8+4+2+1

128+64+32+16+8+4+2+1

0137

153163

127255

Dotted Decimal notationTCP/IP addresses are represented by the so-called 'dotted decimal' notation.

This allocates decimal numbers to the 32 bits in 4 fields each representing 8 bits. e.g. 10000000 00001010 00000010 00011110 becomes 128 . 10 . 2 . 30

IP v.4 addressing classes

net address

Host address

1 8 31 16 24

0 CLASS A

net address Host address

1 8 31 16 24

0 CLASS B 1

net address

Host

1 8 31 16 24

CLASS C address 1 1

IP Address Classes

0

address

1 8 31 16 24

1 1 0 Class D 1 Multicast

IP v.6 The next generation of the Internet

protocol, IP v.6, the deployment of which began in 1999 ,

It has an almost unlimited range of addresses, so sub netting to conserve IP addresses should no longer be a problem .

IPv6 addresses are 128-bit numbers and are conventionally expressed using hexadecimal strings

)for example, 1080:0:0:0:8:800:200C:417A.(

•If the router does not support IPv6 we use TUNNELING .

Tunneling (1)Connects two networks through a middle one

Packets are encapsulates over the middle

Tunneling (2)Tunneling analogy:

tunnel is a link; packet can only enter/exit at ends

Available addressesClass Net_id

FromNet_idto

Nets Hosts

A 0 127 27=128 224=16M

B 128.0 191.255 214=16K 216=64K

C 192.0.0 223.255.255 221=2M 28=256

D 224 239 multicast

E 240 255 reserved

N.B K=1024 , M=1024K127.0.0.0 = special diagnostic address- e.g. loopback =127.0..0.1

Available Addresses

Example: Class B IP Addressing

Network number is 145.10.0.0 First station address is 145.10.0.1 Second station address is 145.10.0.2 etc.

Last station address is ? Broadcast address is 145.10.255.255

Default subnet masks

255.0.0.0 for class A

255.255.0.0 for class B

255.255.255.0 for class C

Masks example

Example 2 Class C addressThe IP address 201.107.2.200 =

11001001 01101011 00000010 11001000

The default class C mask is 255.255.255.0 =11111111 11111111 11111111 00000000

When the mask is ANDed with the IP address it leaves the network part of the address:

11001001 01101011 00000010 1100100011111111 11111111 11111111 00000000 __________________________________11001001 01101011 00000010 00000000 =

The last eight places are all zeros, which translates to 0. and 200 would be the host_id on the network 201.107.2.0.

N.B. Zero in the last place means we don’t care what the host number is; all we are looking at is the network number.

Private IP addresses

10.0.0.0 to 10.255.255.255

172.16.0.0 to 172.31.255.255

192.168.0.0 to 192.168.255.255

APIPA : Automatic Private IP Address range169.254.0.0 to 169.254.255.255

APIPAAutomatic Private IP Address

Range 169.254.0.0 thru 169.254.255.255

Used on small LANs without DHCP server(on a single-subnet network that contains no routers).

Assigns only an IP address and subnet mask

Broadcasts are used to ensure there are no address conflicts

Available on Windows 98 and 2000/XP PCs

DHCP

DHCP: DYNAMIC HOST CONFIGURATION PROTOCOL

Client server service

Client configured for DHCP will seek out a DHCP Server, using broadcasts, in order to obtain a IP address automatically.

DHCP Operation

DHCPCLIENT

DHCPSERVER

DHCPSERVER

DHCPDISCO VER

DHCPO FFER

DHCPREQ UEST

DHCPACK

DHCP LEASE PRO CESS

DHCP operation 2