Subnetting

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Subnetting

• A distributed networks savior
• By Mike Guantonio

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What are public and private Addresses?

• Public addresses are addresses of the outside
  world
• Given to us by the ISP
• Private addresses are addresses inside the
  network that are not seen by the outside world.

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When do we use Public Addresses

• To set up a link to the outside world.
• To set up routers in different parts of a work
  area.

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Why do we need Sub-networks

• Running out of IP addresses
• Waste of IP addresses
• Private numbers that can be used in any
  organization

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Why do we subnet?

• With private networks we can assign a block of
  addresses to various groups
• Finance
• Marketing
• Help Desk
• Development
• This becomes more apparent with the introduction
  of VLans

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What is the advantage of sub-netting?

• We subnet large vs. small networks
• A subnet breaks a network into smaller more
  manageable pieces
• Much like how the phone company breaks down the
  telephone numbers with area codes.

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Can different subnets talk to each other?

• No
• But with the help of switches and/or routers its
  possible
• Nodes in the same subnet can communicate
  independently without any extra protocols needed.

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Classes of Networks

• Class A N.H.H.H
• Class B N.N.H.H
• Class C N.N.N.H

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Class Ranges

• Class A Range10.0.0.0 10.255.255.255
• Class B Range 172.16.00 172.31.255.255
• Class C 192.168.0.0 192.168.255.255

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How to subnet
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What do home routers do?

• Most routers will dish out an address of
  192.168.1.(2-255)
• This is not the address that other computers see
• The reason for this is so that multiple computers
  can connect to the network without needing
  various IPs
• This is called NAT or PAT depending on the
  protocol.

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Works Cited

• Chapman, Bill, and Allan Johnson, Rick Graziani,
  Elaine Horn, Andrew Large, Antoon W. Rufi. CCNA
  1 and 2 Companion Guide. 3rd . Indianapolis,
  Indiana Cisco Press, 2005.