2. SUBNETTING
 IT’S A PROCESS OF DIVIDING A SINGLE NETWORK INTO
MULTIPLE NETWORKS.
 THIS IS DONE BY CONVERTING HOST’S BITS INTO NETWORK’S
BITS (i.e. Converting 0’s into 1’s).
 IT IS ALSO CALLED FLSM.
 IT CAN BE DONE IN THREE WAYS:
 Requirement of network.
 Requirement of hosts.
 Cisco / notation.
 A SUBNET MASK IS ALWAYS A COMBINATION OF CONTIGUOUS
1’s AND 0’s. VALID SUBNET MASKS IN EACH OCTET ARE: 0, 128, 192,
224, 240, 248, 252, 254, 255.

3. REVERSE ENGINEERING
SECNARIO 1 IP ADD : 192.168.1.127 / 27
SECNARIO 2
IP ADD : 172.16.68.65
SUBNET MASK : 255.255.255.240
DEFAULT GATEWAY : 172.16.68.62

4. VLSM
 A VLSM IS A MEANS OF ALLOCATING IP ADDRESSING
RESOURCES TO SUBNETS ACCORDING TO THEIR
INDIVIDUAL NEED RATHER THAN SOME GENERAL
NETWORK WIDE RULE.
 VLSM ALLOWS AN ORGANISATION TO USE MORE
THAN ONE SUBNET MASK WITHIN THE SAME
NWTWORK ADDRESS SPACE. IT IS REFERRED TO AS
“SUBNETTING A SUBNET” AND CAN BE USED TO
MAXIMIZE ADDRESSING EFFICIENCY.
 LARGER SUBNETS ARE CREATED FOR ADDRESSING
LAN’s AND SMALL SUBNETS FOR WAN LINKS (e.g. a 30
bit subnet mask is used to create subnet with only two
hosts).

5. SUBNETTING vs VLSM
SUBNETTING ALLOWS YOU TO DIVIDE BIG
NETWORK INTO SMALLER EQUAL SIZED SLICES.
VLSM ALLOWS YOU TO DIVIDE BIG NETWORK
INTO SMALLER, DIFFERENT-SIZED SLICES. THIS
ALLOWS YOU TO MAKE MAXIMUM USE OF THE
VALUABLE ADDRESS SPACE.

6. ADVANTAGES OF SUBNETTING
REDUCED NETWORK TRAFFIC
OPTIMIZED NETWORK MANAGEMENT
SIMPLIFED NETWORK MANGEMENT