Chabot College
ELEC 99.05
Why Subnet?
CISCO NETWORKING ACADEMY
Why Subnet?
• Security / Access control
• Broadcast control
• WAN links
CISCO NETWORKING ACADEMY
Security / Access Control
• Given one class C network,
• 3 subnets allow access rules to be different for each
workgroup:
CISCO NETWORKING ACADEMY
Security / Access Control
• Access Rules:
– Engineering & Sales can’t access Sr. Management
subnet.
CISCO NETWORKING ACADEMY
Security / Access Control
• Access Rules:
– All departments can access Intenet
CISCO NETWORKING ACADEMY
Broadcast Control
• Given the class C network: 200.35.15.0 /24
• 3 subnets connected by a router
• 3 small broadcast domains
CISCO NETWORKING ACADEMY
WAN Links
• Given one class C network: 200.35.15.0 /24
• No subnets.
• WAN link uses up the only network.
(One IP address on each end of WAN link.)
• No networks available for other segments:
Headquarters
Branch Office
200.35.15.2
200.35.15.1
CISCO NETWORKING ACADEMY
200.35.15.0 /24 net
WAN Links
• Given one class C network: 200.35.15.0 /24
• Subnet /27
• WAN link uses only one of several available subnets:
200.35.15.129
CISCO NETWORKING ACADEMY
200.35.15.128 /27 subnet
200.35.15.130
Headquarters
Branch Office