Network Layer Logical Addressing

8/9/2019 Network Layer Logical Addressing

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Host to Host (Computer to Computer)

Usually computers communicate through internet

Logical Addressing

or IP address in TCP/IP protocol suite IPv4 and IPv6

IPv4 addresses are unique

The address space of IPv4 isor , , ,


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Dotted-decimal notation

Base 256 : IP Addresses

, ,

concept of classes

,

is divided into five classes:

, , , , an


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Finding the classes in binary and

otte - ec ma notat on

Netid

Hostid

Netid and Hostid concept does not apply to clases D and E

,

most of addresses were wasted and were notin use

Block in Class B is also too large

Block of Class C is robabl too small for many organizations

Class D: multicast ---- The internet authorities wron lpredicted a need for 268, 435, 456 groups. This never happened

Class E: were reserved for future use -----only few were used


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,

in blocks

The addresses in a block must be contiguous

e num er o a resses n a oc mus e

a power of 2 (1,2,4,8 ,)

e rs a ress mus e even y v s e y

the number of addresses

The above figure shows a block of addresses,

in both binary and dotted-decimal notation,

granted to a small business that needs 16

addresses


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We can see that the restrictions are applied to thisblock The addresses are contiguous

The number of addresses is a power of 2 (16 = 24)

and the first address is divisible by 16

The first address, when converted to a decimal number, is, , , , , ,

,

addresses can be defined as:

. . .

in which x.y.z.t defines one of the addresses

and the /n defines the mask

The address and the /n notation

completely define the whole block

the first address

the last address

and the number of addresses


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- .

The binary representation of the given. . .

11001101 00010000 00100101 00100111

11001101 00010000 00100101 00100000

or

205.16.37.32.

- .

The binary representation of the given

. . .

11001101 00010000 00100101 00100111

11001101 00010000 00100101 00101111

or

205.16.37.47


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- .

23228= 16

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The first address can be found b ANDinthe given addresses with the mask. ANDinghere is done bit by bit. The result of ANDing

otherwise.


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The last address can be found by ORing the givenaddresses with the complement of the mask. ORing

here is done bit by bit. The result of ORing 2 bits is 0if both bits are 0s; the result is 1 otherwise. Thecomplement of a number is found by changing each1 to 0 and each 0 to 1

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The last address can be found by ORing the givenaddresses with the complement of the mask. ORinghere is done bit by bit. The result of ORing 2 bits is 0if both bits are 0s; the result is 1 otherwise. Thecomplement of a number is found by changing each1 to 0 and each 0 to 1


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complementing the mask, interpreting it as a

decimal number, and adding 1 to it

Network Address

Three level Hierarchy: Subnetting

block of addresses starting with

. . . .

subnets of 32, 16 and 16 addresses.

mask and each subnet must also have

.

Suppose mask for first, second and third

,


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Network AddressThree level Hierarchy: Subnetting

Then n1=27

n3 = 28

s means a we ave e mas s

27,28,28 with the organization mask

e ng

Network Address ContdThree level Hierarchy: Subnetting


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Network Address ContdThree level Hierarchy: Subnetting

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An ISP is granted a block of addresses starting with190.100.0.0/16 (65,536 addresses). The ISP needs todistribute these addresses to three groups ofcustomers as follows:a) The first group has 64 customers; each needs 256

addresses.

b) The second group has 128 customers; each needs 128addresses.

c) The third group has 128 customers; each needs 64addresses.

Design the subblocks and find out how manyaddresses are still available after these allocations.


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Address allocation and distribution

y an

addresses internally

and one address or small set of addresses

externally

Addresses for private networks reserved by internet authorities


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100,000 dialup Customers


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Network la er at the source router and destination

, ,


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colon notation:


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Position of IPv4 in TCP/IP protocol suite


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Transition strategies from IPv4 to

v

A station must run IPv4 and IPv6 simultaneously until all

the Internet uses IPv6.

be decided by DNS.


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Two computers using IPv6 want to communicate

And the packet must pass through a region that

uses IPv4.

The sender wants to use IPv6 but receiver doesnot understand IPV6

In this case, tunneling will not work. Therefore

IPv4 header.


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Simplified forwarding module in classless address

Configuration for Example


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Configuration for Example

out ng ta e or router

Hierarchical routing with ISPs


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Documents

Network Layer Logical Addressing