Transcript PowerPoint Presentation from Subnetting Part1 and Part2

Subnetting
Subnetting
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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
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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
10010100
8
00001000
20
00010100
10
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.D
Class
1st Octet
Number of
Networks
Number of
Hosts
A
1-126
126
B
128-191
16,384
224 =
16,777,216
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
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What is subnetting
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–
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
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Why subnet
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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
Tower box
Router
1.) Determine # of subnets
Router
Router
Tower box
Router
2.) Determine # of bits you can
borrow
200
1100 1000
148
1001 0100
11
0000 1011
10
0000 1010
8
0000 1000
0
hhhh hhhh
20
0001 0100
0
hhhh hhhh
0
hhhh hhhh
0
hhhh hhhh
0
hhhh hhhh
0
hhhh 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 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
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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
200.10.20.64
200.10.20.96
200.10.20.63
200.10.20.95
200.10.20.127
200.10.20.128
200.10.20.160
200.10.20.159
200.10.20.191
200.10.20.192
200.10.20.224
200.10.20.223
200.10.20.255
Useable IP addresses
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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