Ethernet Basics – 7 IP Addressing

Introducing IP Addressing  IP address (TCP/IP address)  Not unique (but should be), user assigned  Layer 3  4 byte (32 bit)  Network part + host part  or 4,290 million different addresses  Always accompanied by a subnet mask IP Address : Subnet Mask :

IP Address Classes net id – 7 bitshost id – 24 bits0 I I I 0 I III 0 III0 net id – 14 bits net id – 21 bits multicast group id – 28 bits reserved for future use – 28 bits Class A Class B host id – 16 bits host id – 8 bits Class C Class D Class E  There are 5 different classes

IP Address Ranges Every interface on an internet must have a unique IP address ClassRange A to B to C to D to E to

Subnets The subnet defines what part of the IP address is net id and what part is host id. It is a binary mask applied to the IP address –Consider the IP address –This is a class B address, (subnet mask = ) therefore the net id should be and the host id – IP Address subnet mask –But that would mean having computers on the same network – lots of potential broadcast traffic –So to split this up we use subnets

Subnets Subnet mask –This is applied to the IP address to evaluate the new net id. –Consider –Give this a subnet of means it now belongs to the network as opposed to the original of – IP Address subnet mask –This means only 254 computers are connected together. –To communicate between subnets, you have to use a router

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