Post on 31-Dec-2015
transcript
Subnetting
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
Binary to Decimal Conversion
Place Card Method
128 64 32 16 8 4 2 1
27 26 25 24 23 22 21 20
Binary to Decimal Conversion
Place Card Method for 1100 0000
128 64 32 16 8 4 2 1
27 26 25 24 23 22 21 20
1 1 0 0 0 0 0 0
192 = 128 + 64 + 0 + 0 + 0 + 0 + 0 + 0
Binary to Decimal Conversion
Place Card Method for 1111 0000
128 64 32 16 8 4 2 1
27 26 25 24 23 22 21 20
1 1 1 1 0 0 0 0
240 = 128 + 64 + 32 + 16 + 0 + 0 + 0 + 0
Decimal to Binary Conversion
Place Card Method for 129
128 64 32 16 8 4 2 1
27 26 25 24 23 22 21 20
129 = 128 + 0 + 0 + 0 + 0 + 0 + 0 + 1
Decimal to Binary Conversion
Place Card Method for 129
128 64 32 16 8 4 2 1
27 26 25 24 23 22 21 20
1 0 0 0 0 0 0 1
129 = 128 + 0 + 0 + 0 + 0 + 0 + 0 + 1
Decimal to Binary Conversion
Place Card Method for 255
128 64 32 16 8 4 2 1
27 26 25 24 23 22 21 20
1 1 1 1 1 1 1 1
129 = 128 + 64 + 32 +16 + 8 + 4 + 2 + 1
IP Address
Example of an IP address is 148.8.20.10 (4 octets) Each octet is an 8 bit binary number Therefore, an IP address is 32 bits.
148 8 20 10
10010100 00001000 00010100 00001010
IP Address
Each IP address is broken up into a Network Address and a Host address
148 8 20 10
10010100 00001000 00010100 00001010
IP Address Classes
Class Network Address Host Address
A 1st Octet Last three Octets
B 1st Two Octets Last Two Octets
C 1st Three Octets Last Octet
IP Address Classes
A . B . C . DClass 1st Octet Number of
NetworksNumber of Hosts
A 1-126 126 224 = 16,777,216
B 128-191 16,384 216 = 65,536
C 192-223 2,097,152 28 = 256
Subnet Masks
Tells the device which bits are host address and network address.
Class Subnet Mask
Binary
A 255.0.0.0 11111111.00000000.00000000.00000000
B 255.255.0.0 11111111. 11111111. 00000000.00000000
C 255.255.255.0 11111111. 11111111. 1111111.00000000
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
Class Subnet Mask
Binary
A 255.0.0.0 11111111.00000000.00000000.00000000
B 255.255.0.0 11111111. 11111111. 00000000.00000000
C 255.255.255.0 11111111. 11111111. 1111111.00000000
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 200.10.20.0
Router
Router Router
Tower box
1.) Determine # of subnets
Router
Router Router
Tower box
2.) Determine # of bits you can borrow
200
1100 1000
10
0000 1010
20
0001 0100
0
hhhh hhhh
148
1001 0100
8
0000 1000
0
hhhh hhhh
0
hhhh hhhh
11
0000 1011
0
hhhh hhhh
0
hhhh hhhh
0
hhhh hhhhFor 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 Bits Useable 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.
1 1 1 0 0 0 0 0
Sub Sub Sub Host Host Host Host 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.
200.10.20.0 200.10.20.
200.10.20. 200.10.20.
200.10.20. 200.10.20.
200.10.20. 200.10.20.
200.10.20. 200.10.20.
200.10.20. 200.10.20.
200.10.20. 200.10.20.
200.10.20. 200.10.20.
7.) Determine Range of IP Addresses in each subnet
We’ve determined that there are 32 hosts per subnet.
200.10.20.0 200.10.20.31
200.10.20.32 200.10.20.63
200.10.20.64 200.10.20.95
200.10.20.96 200.10.20.127
200.10.20.128 200.10.20.159
200.10.20.160 200.10.20.191
200.10.20.192 200.10.20.223
200.10.20.224 200.10.20.255
Useable IP addresses
We discard the 1st and last subnet Discard the 1st and last IP address in each
subnet. Our 1st useable IP address in the first
useable subnet that can be assigned to a node on our network would be:– 200.10.20.33