9.2.1.3 Lab - Designing and Implementing a Subnetted IPv4 Addressing Scheme

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Lab - Designing and Implementing a Subnetted IPv4 Addressing Scheme

© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 3 of 7

3) The network that you are tasked to subnet is 192.168.0.0/24. What is the /24 subnet mask in binary?

4) The subnet mask is made up of two portions, the network portion, and the host portion. This is represented in the binary by the ones and the zeros in the subnet mask.

In the network mask, what do the ones represent?

In the network mask, what do the zeros represent?

5) To subnet a network, bits from the host portion of the original network mask are changed into subnet bits. The number of subnet bits defines the number of subnets. Given each of the possible subnet masks depicted in the following binary format, how many subnets and how many hosts are created in each example?

Hint: Remember that the number of host bits (to the power of 2) defines the number of hosts per subnet (minus 2), and the number of subnet bits (to the power of two) defines the number of subnets. The subnet bits (depicted in bold type face) are the bits that have been borrowed beyond the original network mask of /24. The /24 is the slash prefix notation and corresponds to a dotted decimal mask of 255.255.255.0.

(/25) 11111111.11111111.11111111.10000000

Dotted decimal subnet mask equivalent:

Number of subnets? Number of hosts?

(/26) 11111111.11111111.11111111.11000000



(/27) 11111111.11111111.11111111.11100000



(/28) 11111111.11111111.11111111.11110000



(/29) 11111111.11111111.11111111.11111000



(/30) 11111111.11111111.11111111.11111100



6) Considering your answers, which subnet masks meet the required number of minimum host addresses?

7) Considering your answers, which subnet masks meets the minimum number of subnets required?

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Lab - Designing and Implementing a Subnetted IPv4 Addressing Scheme

© 2013 Cisco and/or its affiliates. All rights reserved. This document is Cisco Public. Page 6 of 7

Reflection

1. Subnetting one larger network into multiple smaller subnetworks allows for greater flexibility and security in network design. However, what do you think some of the drawbacks are when the subnets are limited to being the same size?

2. Why do you think the gateway/router IP address is usually the first usable IP address in the network?

Router Interface Summary Table

Router Interface Summary

Router Model Ethernet Interface #1 Ethernet Interface #2 Serial Interface #1 Serial Interface #2

1800 Fast Ethernet 0/0 (F0/0)

Fast Ethernet 0/1 (F0/1)

Serial 0/0/0 (S0/0/0) Serial 0/0/1 (S0/0/1)

1900 Gigabit Ethernet 0/0 (G0/0)

Gigabit Ethernet 0/1 (G0/1)

Serial 0/0/0 (S0/0/0) Serial 0/0/1 (S0/0/1)



Serial 0/1/0 (S0/1/0) Serial 0/1/1 (S0/1/1)



Serial 0/0/0 (S0/0/0) Serial 0/0/1 (S0/0/1)

2900 Gigabit Ethernet 0/0 (G0/0)

Gigabit Ethernet 0/1 (G0/1)

Serial 0/0/0 (S0/0/0) Serial 0/0/1 (S0/0/1)

Note: To find out how the router is configured, look at the interfaces to identify the type of router and how many interfaces the router has. There is no way to effectively list all the combinations of configurations for each router class. This table includes identifiers for the possible combinations of Ethernet and Serial interfaces in the device. The table does not include any other type of interface, even though a specific router may contain one. An example of this might be an ISDN BRI interface. The string in parenthesis is the legal abbreviation that can be used in Cisco IOS commands to represent the interface.

Appendix A: Configuration Details for Steps in Part 2

Step 1: Configure the router.

a. Console into the router and enable privileged EXEC mode.

Router> enable Router#

b. Enter into configuration mode.

Router# conf t Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#

c. Assign a device name to the router.

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9.2.1.3 Lab - Designing and Implementing a Subnetted IPv4 Addressing Scheme