Subnetting

Binary to Decimal Conversion Decimal to Binary Conversion Classes of IP Addresses Subnet Masks 7 step method to practical subnetting – Class C – Class B

Binary to Decimal Conversion

Place Card Method

Binary to Decimal Conversion Place Card Method for =

Binary to Decimal Conversion Place Card Method for =

Decimal to Binary Conversion Place Card Method for =

Decimal to Binary Conversion Place Card Method for =

Decimal to Binary Conversion Place Card Method for =

IP Address Example of an IP address is (4 octets) Each octet is an 8 bit binary number Therefore, an IP address is 32 bits

IP Address Each IP address is broken up into a Network Address and a Host address

IP Address Classes ClassNetwork AddressHost Address A1 st OctetLast three Octets B1 st Two OctetsLast Two Octets C1 st Three OctetsLast Octet

IP Address Classes A. B. C. D Class1 st OctetNumber of Networks Number of Hosts A = 16,777,216 B , = 65,536 C ,097, = 256

Subnet Masks Tells the device which bits are host address and network address. ClassSubnet Mask Binary A B C

Subnetting What is subnetting – Process of subdividing a single class of network into multiple subnetworks. – A subnetted network address contains a network address, subnet address and host address.

Subnetting ClassSubnet Mask Binary A B C

Subnetting Why subnet – Reduce Collision Domain – Makes it easier to manage your network (lower TCO) – Makes you network more secure

Class C Subnet Example – Assigned

1.) Determine # of subnets

2.) Determine # of bits you can borrow hhhh hhhh 0 hhhh hhhh 0 hhhh 0 hhhh For a class C address we have 8 host address bits to work with. You need to borrow at least 2 bits for the subnet address and you must leave at least 2 host bits for the host address. Therefore, we can borrow 2 to 6 bits on a class C address.

3.) Determine # of bits you need to borrow 2^n -2 = number of useable subnets Borrowed BitsUseable Subnets Useable Host Addresses

4.) High Order Bits Set the high order bits (determined above) to 1.

5.) Subnet Mask Combine the Default Subnet Mask with value determined in step #4.

6.) Determine the IP range of each subnet Sub Host 5 host address bits or 2^5 hosts per subnet

7.) Determine Range of IP Addresses in each subnet We’ve determined that there are 32 hosts per subnet

7.) Determine Range of IP Addresses in each subnet We’ve determined that there are 32 hosts per subnet

Useable IP addresses We discard the 1 st and last subnet Discard the 1 st and last IP address in each subnet. Our 1 st useable IP address in the first useable subnet that can be assigned to a node on our network would be: –