sub netting
TRANSCRIPT
Sub Netting
Objectives - Sub netting CIDR Subnet Mask Formula for sub netting Class C Sub netting Class B Sub netting Class A Sub netting
Sub Netting
With the rapid growth of the internet & the ever-increasing demand for new IP addresses, the standard address class structure has been expanded by borrowing bits from the Host portion to allow for more Networks.
Sub Netting
Dividing a single network into multiple networks.
Converting Host bits into network bits. i.e. converting 0’s into 1’s.
Sub netting can be done in three ways.• Requirement of Network• Requirement of Host• / Notation
Sub Netting Rules The key concept of sub netting is borrowing
bits from the host portion of the network to create a sub network.
Rules govern this borrowing, ensuring that some bits are left for a Host ID.
The rules require that two bits remain available to use for the Host ID.
Sub NettingBits available for Creating Subnets
Address class Network bits Host bits Bits available
for subnet
CLASS A 8 24 24-2 = 22
CLASS B 16 16 16-2 = 14
CLASS C 24 8 8-2 = 6
Sub Netting
128 64 32 16 8 4 2 1
1 0 0 0 0 0 0 0 1281 1 0 0 0 0 0 0 1921 1 1 0 0 0 0 0 2241 1 1 1 0 0 0 0 2401 1 1 1 1 0 0 0 2481 1 1 1 1 1 0 0 2521 1 1 1 1 1 1 0 2541 1 1 1 1 1 1 1 255
Binary place value
Binary Digit Decimal
Equivalent
Sub Net mask value
CIDRCIDR – Classless Inter-Domain Routing.
CIDR addressing method allows the use of a prefix to designate the number of network bits in the mask
For Example: 200.15.1.53/25 (CIDR Notation)
In this example the CIDR value is /25 means the first 25 bits in the mask are network bits (1s)
Subnet Mask
Subnet mask : It is used to determine the network portion and Host portion of an IP address.
Address Class Subnet mask Octet Format
CLASS A 255.0.0.0 N.H.H.H
CLASS B 255.255.0.0 N.N.H.H
CLASS C 255.255.255.0 N.N.N.H
N = Network H = Host
Sub netting formula
Network = 2n [n = number of ON bits (1’s)]Host = 2h [h = number of OFF bits (0’s)]Valid Host = Host – 2 *
* First IP (Host) of Network is use for network address * Last IP (Host) of network is use for Broadcast address
192.168.1.0255.255.255.011111111.11111111.11111111.00000000
IP AddressSubnet MaskBinary format
Network Bits Host Bits
CLASS C Sub netting 192.168.1.0 divided into in 64 Hosts.
Subnet mask : 255.255.255.0Binary form : 11111111.11111111.11111111.00000000
Network : 2n => 22 = 4Host : 2h => 26 = 64Valid Host : Host – 2 => 64 – 2 = 62
New Binary form : 11111111.11111111.11111111.11000000New Subnet mask : 255.255.255.192
CIDR : /24
New CIDR : /26
n = no. of ON bits.
h = no. of OFF bits
Block size : 256 – 192 = 64
CLASS C Sub netting
No.
Network/Network ID Broadcast ID First Host Last Host
1 192.168.1.0 192.168.1.63 192.168.1.1 192.168.1.62
2 192.168.1.64 192.168.1.127 192.168.1.65 192.168.1.126
3 192.168.1.128 192.168.1.191 192.168.1.129 192.168.1.190
4. 192168.1.192 192.168.1.255 192.168.1.193 192.168.1.254
192.168.1.0 divided into in 64 Hosts.
CLASS B Sub netting 172.18.0.0 divided into in 8 Networks.
Subnet mask : 255.255.0.0Binary form : 11111111.11111111.00000000.00000000
Network : 2n => 23 = 8Host : 2h => 213 = 8192Valid Host : Host – 2 => 8192 – 2 = 8190
New Binary form : 11111111.11111111.11100000.00000000New Subnet mask : 255.255.224.0
CIDR : /16
New CIDR : /19
Block Size : 256 – 224 = 32
n = no. of ON bits.
h = no. of OFF bits
CLASS B Sub netting
S No Network/Network ID Broadcast ID First Host Last Host
1 172.18.0.0 172.18.31.255 172.18.0.1 172.18.31.2542 172.18.32.0 172.18.63.255 172.18.32.1 172.18.63.2543 172.18.64.0 172.18.91.255 172.18.64.1 172.18.91.2544 172.18.92.0 172.18.127.255 172.18.92.1 172.18.127.2545 172.18.128.0 172.18.159.255 172.18.128.1 172.18.159.2546 172.18.160.0 172.18.191.255 172.18.160.1 172.18.191.2547 172.18.192.0 172.18.223.255 172.18.192.1 172.18.223.2548 172.18.224.0 172.18.255.255 172.18.224.1 172.18.255.254
172.18.0.0 divided into in 8 Networks.
CLASS A Sub netting Find the Broadcast ID of this network 110.60.21.15/11
Subnet mask : 255.0.0.0Binary form : 11111111.00000000.00000000.00000000
Network : 2n => 23 = 8Host : 2h => 221 = 2097152Valid Host : Host – 2 => 2097152 – 2 = 2097150
New Binary form : 11111111.11100000.00000000.00000000New Subnet mask : 255.224.0.0
CIDR : /8
New CIDR : /11
Block Size : 256 – 224 = 32
n = no. of ON bits.
h = no. of OFF bits
CLASS A Sub netting
S No
Network/Network ID Broadcast ID First Host Last Host
1 110.0.0.0 110.31.255.255 110.0.0.1 110.31.255.2542 110.32.0.0 110.63.255.255 110.32.0.1 110.63.255.2543 110.64.0.0 110.91.255.255 110.64.0.1 110.91.255.2544 110.92.0.0 110.127.255.255 110.92.0.1 110.127.255.2545 110.128.0.0 110.159.255.255 110.128.0.1 110.159.255.2546 110.160.0.0 110.191.255.255 110.160.0.1 110.191.255.2547 110.192.0.0 110.223.255.255 110.192.0.1 110.223.255.2548 110.224.0.0 110.255.255.255 110.224.0.1 110.255.255.254
2 110.32.0.0 110.63.255.255 110.32.0.1 110.63.255.254
Find the Broadcast ID of this address 110.60.21.15/11
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