lecture7:subnetting network2

We subnet our network to overcome issues with location, size, and control. In designing the addressing, we consider the factors for grouping the hosts that we discussed previously:
• Grouping based on common geographic location
• Grouping hosts used for specific purposes
• Grouping based on ownership
Each WAN link is a network. We create subnets for the WAN that interconnect different geographic locations. When connecting the different locations, we use a router to account for the hardware differences between the LANs and the WAN.
Although hosts in a common geographic location typically comprise a single block of addresses, we may need to subnet this block to form additional networks at each location. We need to create subnetworks at the different locations that have hosts
for common user needs. We may also have other groups of users that require many network resources, or we may have many users that require their own subnetwork. Additionally, we may have subnetworks for special hosts such as servers. Each of these factors needs to be considered in the network count.
We also have to consider any special security or administrative ownership needs that require additional networks.
One useful tool in this address planning process is a network diagram. A diagram allows us to see the networks and make a more accurate count.
To accommodate 800 hosts in the company s four locations, we use binary arithmetic to allocate a /22 block (2^10-2=1022).
Allocating Addresses
Now that we have a count of the networks and the number of hosts for each network, we need to start allocating addresses from our overall block of addresses.
See Step 3 of the figure.