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Vlsm
wonder[riya7
Banned Posts: 41 ■■□□□□□□□□
in CCNA & CCENT
In class he did variable length subnet masks. What is it and how does one do sums with it?
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Nisseki
Member Posts: 160
What resources are you using to study for your cisco?
I'm using Todd Lammle's book and video series on IT Pro TV, he explains it quite well. -
Optionswonder[riya7
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I got the book. How long will it take to read the book?
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CryptoQue
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wonder[riya7 VLSM is used to scale standard subnets (i.e. Class C) to fit network requirements. For example, if you're redesigning a network for a company that has 3 departments they want to keep isolated. Department 1 (HR) has 105 computers, department 2 (Finance) has 40 computers, and department 3 (Public Relations) has 55 computers. The company currently has all departments configured on a 192.168.1.0/24 network. You can use VLSM to meet the company's needs. You would breakdown the class C into smaller subnets that are comparable to the amount of hosts that will be connected.
Network Subnet = 192.168.1.0/24
HR = 105 computers = /25 = 126 usable IPs
Finance = 40 computers = /26 = 62 usable IPs <---couldn't use a /27 because the maximum usable IPs for it is only 30
Public Relations = 55 computers = 62 usable IPs
New Networks
HR = 192.168.1.0/25
Finance = 192.168.1.128/26
Public Relations = 192.168.1.192/26
New IP Ranges
HR = 192.168.1.1 - 192.168.1.126
Finance = 192.168.1.129 - 192.168.1.190
Public Relations = 192.168.1.193 - 192.168.1.254
*routing will need to be involved in this process, but that's a more detailed topic you can find a lot of research on.