Vslm subneteo

0
1010100 10001111100 1011100101011100 101100011101001 1011110100011010 00001010010110010 1001010101100111 1111010101000101 1101001101010011 001010010101010 1010101000110010 010101001011000 110101100011010 11010100001011 001010100110 1001010010

10.250.1.0

172.16.1.0

VLSM
Version 2.0 Version 1.0

Variable-Length Subnet Mask

Workbook

192.168.10.0 192.168.10.96
Student Name:192.168.10.126

172.31.15.0

IP Address Classes
Class A Class B Class C Class D Class E 1 – 127 128 – 191 192 – 223 224 – 239 240 – 255 (Network 127 is reserved for loopback and internal testing) 00000000.00000000.00000000.00000000 Leading bit pattern 0 Network . Host . Host . Host Leading bit pattern Leading bit pattern 10 110
10000000.00000000.00000000.00000000
Network . Network . Host .Host

11000000.00000000.00000000.00000000
Network . Network . Network . Host

(Reserved for multicast) (Reserved for experimental, used for research)

Private Address Space
Class A Class B Class C 10.0.0.0 to 10.255.255.255 172.16.0.0 to 172.31.255.255 192.168.0.0 to 192.168.255.255

Default Subnet Masks
Class A Class B Class C 255.0.0.0 255.255.0.0 255.255.255.0

This workbookassumes you already have a background in subnetting. If you don’t you may want to consider completing the IP Addressing and Subnetting Workbook.
Produced by: Robb Jones jonesr@careertech.net and/or Robert.Jones@fcps.org Frederick County Career & Technology Center Cisco Networking Academy Frederick County Public Schools Frederick, Maryland, USA Special Thanks to Melvin Baker and Jim Dorsch for takingthe time to check this workbook for errors.

Workbooks included in the series: IP Addressing and Subnetting Workbooks ACLs - Access Lists Workbooks VLSM Variable-Length Subnet Mask IWorkbooks Inside Cover

Classful vs. Classless Subnetting
When you’re subnetting an IP address for a network you have two options: classful and classless. Classful subnetting is the simplest method. It tends to bethe most wasteful because it uses more addresses than are necessary. In classful subnetting you use the same subnet mask for each subnet, and all the subnets have the same number of addresses in them. Classless addressing allows you to use different subnet masks and create subnets tailored to the number of users in each group. This technique is referred to as VLSM, Variable Length Subnet Masks.What is VLSM
Variable Length Subnet Masks allow you a much tighter control over your addressing scheme. If you use a class C address with a default subnet mask you end up with one subnet containing 256 addresses. By using VLSM you can adjust the number of subnets and number of addresses depending on the specific needs of your network. The same rules apply to a class A or B addresses. VLSM issupported by the following protocols: RIP version 2, OSPF, EIGRP, Dual IS-IS, and BGP. You need to configure your router for Variable Length Subnet Masks by setting up one of these protocols. Then configure the subnet masks of the various interfaces in the IP address interface subcommand.

Benefits of VLSM
Allows efficient use of address space Allows the use of multiple subnet mask lengths Breaksup an address block into smaller custom blocks Allows for route summarization Provides more flexibility in network design Supports hierarchical enterprise networks

This workbook explores three different methods to figure out sub-subnets: the box method, the circle method, and a VLSM chart.
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Classful Subnetting Example
When you’re subnetting an IP address for a network you have twooptions: classful and classless. Classful subnetting is the simplest method. It also tends to be the most wasteful because it uses more addresses than are necessary. In classful subnetting you use the same subnet mask for each subnet, and all the subnets have the same number of addresses in them. In this example you need five subnets, each one containing 30 hosts. The serial connections only require...