Lab $-$ Design and Implement a VLSM Addressing Scheme

Topology

Objectives

Part $1$: Examine Network Requirements Part $2$: Design the VLSM Address Scheme

Part $3$: Cable and Configure the IPv$4$ Network

Background $/$ Scenario

Variable Length Subnet Mask $($VLSM$)$ was designed to avoid wasting IP addresses. With VLSM$,$ a network is subnetted and then re$-$subnetted. This process can be repeated multiple times to create subnets of various sizes based on the number of hosts required in each subnet. Effective use of VLSM requires address planning.

In this lab, use the $192\mathrm{.}168\mathrm{.}33\mathrm{.}128/25$ network address to develop an address scheme for the network displayed in the topology diagram. VLSM is used to meet the IPv$4$ addressing requirements. After you have designed the VLSM address scheme, you will configure the interfaces on the routers with the appropriate IP address information. The future LANS at BR$2$ will need to have addresses allocated, but no interfaces will be configured at this time.

Note: The routers used with CCNA hands$-$on labs are Cisco $4221$ with Cisco IOS XE Release $16\mathrm{.}9\mathrm{.}4($universalk$9$ image$).$ The switches used in the labs are Cisco Catalyst $2960$s with Cisco IOS Release $15\mathrm{.}2(2)($lanbasek$9$ image$).$ Other routers, switches, and Cisco IOS versions can be used. Depending on the model and Cisco IOS version, the commands available and the output produced might vary from what is shown in the labs. Refer to the Router Interface Summary Table at the end of the lab for the correct interface identifiers.

Note: Make sure that the routers have been erased and have no startup configurations. If you are unsure, contact your instructor.

Required Resources

$2$ Routers $($Cisco $4221$ with Cisco IOS XE Release $16\mathrm{.}9\mathrm{.}4$ universal image or comparable$)$

$2$ Switches $($Cisco $2960$ with Cisco IOS Release $15\mathrm{.}2(2)$ lanbasek$9$ image or comparable$)$

$1$ PCs $($Windows with terminal emulation program, such as Tera Term$)$

$$ Console cables to configure the Cisco IOS devices via the console ports

$$ Ethernet and serial cables as shown in the topology

$$ Windows Calculator $($optional$)$

Instructions

Part $1$: Examine Network Requirements

In Part $1,$ you will examine the network requirements to develop a VLSM address scheme for the network displayed in the topology diagram using the $192\mathrm{.}168\mathrm{.}33\mathrm{.}128/25$ network address.

Note: You can use the Windows Calculator application and search the internet for an IP subnet calculator to help with your calculations.

Step $1$: Determine how many host addresses and subnets are available.

How many host addresses are available in a $/25$ network?

What is the total number of host addresses needed in the topology diagram?

How many subnets are needed in the network topology?

Step $2$: Determine the largest subnet.

What is the subnet description $($e$.$g$.$ BR$1$ LAN or BR$1-$BR$2$ link$)?$

How many IP addresses are required in the largest subnet?

What subnet mask can support that many host addresses?

How many total host addresses can that subnet mask support?

Can you subnet the $192\mathrm{.}168\mathrm{.}33\mathrm{.}128/25$ network address to support this subnet?

What are the network addresses that would result from this subnetting?

Use the first network address for this subnet.

Step $3$: Determine the second largest subnet.

What is the subnet description?

How many IP addresses are required for the second largest subnet?

What subnet mask can support that many host addresses?

How many total host addresses can that subnet mask support?

Can you subnet the remaining subnet again and still support this subnet?

What are the network addresses that would result from this subnetting?

Use the first network address for this subnet.

Step $4$: Determine the third largest subnet.

What is the subnet description?

How many IP addresses are required for the next largest subnet?

What subnet mask can support that many host addresses?

How many total host addresses can that subnet mask support?

Can you subnet the remaining subnet again and still support this subnet?

What are the network addresses that would result from this subnetting?

Use the first network address for this subnet.

Use the second network address for the CCTV LAN. Use the third network address for the HVAC C$2$ LAN.

Step $5$: Determine the fourth largest subnet.

What is the subnet description?

How many IP addresses are required for the next largest subnet?

What subnet mask can support that many host addresses?

How many total host addresses can that subnet mask support?

Can you subnet the remaining subnet again and still support this subnet?

What are the network addresses that would result from this subnetting?

Use the first network address for this subnet.

Part $2$: Design the VLSM Address Scheme

Step $1$: Calculate the subnet information.

Use the information that you obtained in Part $1$ to fill in the following table.

Subnet Description Number of Hosts Needed Network