Appendix Lab – Subnetting Network Topologies Answers

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Appendix Lab – Subnetting Network Topologies Answers

Lab – Subnetting Network Topologies (Answers Version)

Answers Note: Red font color or Gray highlights indicate text that appears in the instructor copy only.

Objectives

Parts 1 to 5, for each network topology:

  • Determine the number of subnets.
  • Design an appropriate addressing scheme.
  • Assign addresses and subnet mask pairs to device interfaces.
  • Examine the use of the available network address space and future growth potential.

Background / Scenario

When given a network topology, it is important to be able to determine the number of subnets required. In this lab, several scenario topologies will be provided, along with a base network address and mask. You will subnet the network address and provide an IP addressing scheme that will accommodate the number of subnets displayed in the topology diagram. You must determine the number of bits to borrow, the number of hosts per subnet, and potential for growth as specified by the instructions.

Part 1: Network Topology A

In Part 1, you have been given the 192.168.10.0/24 network address to subnet, with the following topology. Determine the number of networks needed and then design an appropriate addressing scheme.

Step 1: Determine the number of subnets in Network Topology A.

  1. How many subnets are there? ___________ 2
  2. How many bits should you borrow to create the required number of subnets? _________ 1
  3. How many usable host addresses per subnet are in this addressing scheme? ___________ 126
  4. What is the new subnet mask in dotted decimal format? _________________________ 255.255.255.128
  5. How many subnets are available for future use? _______________ 0

Step 2: Record the subnet information.

Fill in the following table with the subnet information:

Subnet Number

Subnet Address

First Usable Host Address

Last Usable Host Address

Broadcast Address

0

192.168.10.0

192.168.10.1

192.168.10.126

192.168.10.127

1

192.168.10.128

192.168.10.129

192.168.10.254

192.168.10.255

2

        

3

        

4

        

5

        

Part 2: Network Topology B

The network topology from Part 1 has expanded to accommodate the addition of router R3 and its accompanying network, as illustrated in the following topology. Use the 192.168.10.0/24 network address to provide addresses to the network devices, and then design a new addressing scheme to support the additional network requirement.

Step 1: Determine the number of subnets in Network Topology B.

  1. How many subnets are there? ___________ 4
  2. How many bits should you borrow to create the required number of subnets? _________ 2
  3. How many usable host addresses per subnet are in this addressing scheme? ___________ 62
  4. What is the new subnet mask in dotted decimal format? _________________________ 255.255.255.192
  5. How many subnets are available for future use? _______________ 0

Step 2: Record the subnet information.

Fill in the following table with the subnet information:

Subnet Number

Subnet Address

First Usable Host Address

Last Usable Host Address

Broadcast Address

0

192.168.10.0

192.168.10.1

192.168.10.62

192.168.10.63

1

192.168.10.64

192.168.10.65

192.168.10.126

192.168.10.127

2

192.168.10.128

192.168.10.129

192.168.10.190

192.168.10.191

3

192.168.10.192

192.168.10.193

192.168.10.254

192.168.10.255

4

        

5

        

6

        

7

        

Part 3: Network Topology C

The topology has changed again with a new LAN added to R2 and a redundant link between R1 and R3. Use the 192.168.10.0/24 network address to provide addresses to the network devices. Also provide an IP address scheme that will accommodate these additional devices. For this topology, assign a subnet to each network.

Step 1: Determine the number of subnets in Network Topology C.

  1. How many subnets are there? ___________ 6
  2. How many bits should you borrow to create the required number of subnets? _________ 3
  3. How many usable host addresses per subnet are in this addressing scheme? ___________ 30
  4. What is the new subnet mask in dotted decimal format? _________________________ 255.255.255.224
  5. How many subnets are available for future use? _______________ 2

Step 2: Record the subnet information.

Fill in the following table with the subnet information:

Subnet Number

Subnet Address

First Usable Host Address

Last Usable Host Address

Broadcast Address

0

192.168.10.0

192.168.10.1

192.168.10.30

192.168.10.31

1

192.168.10.32

192.168.10.33

192.168.10.62

192.168.10.63

2

192.168.10.64

192.168.10.65

192.168.10.94

192.168.10.95

3

192.168.10.96

192.168.10.97

192.168.10.126

192.168.10.127

4

192.168.10.128

192.168.10.129

192.168.10.158

192.168.10.159

5

192.168.10.160

192.168.10.161

192.168.10.190

192.168.10.191

6

192.168.10.192

192.168.10.193

192.168.10.222

192.168.10.223

7

192.168.10.224

192.168.10.225

192.168.10.254

192.168.10.255

8

        

9

        

10

        

Step 3: Assign addresses to network devices in the subnets.

  1. Fill in the following table with IP addresses and subnet masks for the router interfaces:
    Answers Note: These are suggested IP addresses based on using the first 6 subnets from the table above as assigned to each segment.

    Device

    Interface

    IP Address

    Subnet Mask

    R1

    GigabitEthernet 0/1

    192.168.10.1

    255.255.255.224
     

    Serial 0/0/0

    192.168.10.33

    255.255.255.224
     

    Serial 0/0/1

    192.168.10.65

    255.255.255.224

    R2

    GigabitEthernet 0/1

    192.168.10.97

    255.255.255.224
     

    Serial 0/0/0

    192.168.10.34

    255.255.255.224
     

    Serial 0/0/1

    192.168.10.129

    255.255.255.224

    R3

    GigabitEthernet 0/1

    192.168.10.161

    255.255.255.224
     

    Serial 0/0/0

    192.168.10.66

    255.255.255.224
     

    Serial 0/0/1

    192.168.10.130

    255.255.255.224
  2. Fill in the following table with the IP addresses and subnet masks for devices in the LAN as displayed in topology.
    Answers Note: These are suggested IP addresses based on using the first 6 subnets from the table above as assigned to each segment.

    Device

    Interface

    IP Address

    Subnet Mask

    Default Gateway

    PC-A

    NIC

    192.168.10.30

    255.255.255.224

    192.168.10.1

    PC-B

    NIC

    192.168.10.29

    255.255.255.224

    192.168.10.1

    S1

    VLAN 1

    192.168.10.2

    255.255.255.224

    192.168.10.1

    PC-C

    NIC

    192.168.10.126

    255.255.255.224

    192.168.10.97

    PC-D

    NIC

    192.168.10.125

    255.255.255.224

    192.168.10.97

    S2

    VLAN 1

    192.168.10.98

    255.255.255.224

    192.168.10.97

    PC-E

    NIC

    192.168.10.190

    255.255.255.224

    192.168.10.161

    PC-F

    NIC

    192.168.10.189

    255.255.255.224

    192.168.10.161

    S3

    VLAN 1

    192.168.10.162

    255.255.255.224

    192.168.10.161

Part 4: Network Topology D

The network was modified to accommodate changes in the organization. The 192.168.10.0/24 network address is used to provide the addresses in the network.

Step 1: Determine the number of subnets in Network Topology D.

  1. How many subnets are there? ___________ 9
  2. How many bits should you borrow to create the required number of subnets? _________ 4
  3. How many usable host addresses per subnet are in this addressing scheme? ___________ 14
  4. What is the new subnet mask in dotted decimal format? _________________________ 255.255.255.240
  5. How many subnets are available for future use? _______________ 7

Step 2: Record the subnet information.

Fill in the following table with the subnet information.

Subnet Number

Subnet Address

First Usable Host Address

Last Usable Host Address

Broadcast Address

0

192.168.10.0

192.168.10.1

192.168.10.14

192.168.10.15

1

192.168.10.16

192.168.10.17

192.168.10.30

192.168.10.31

2

192.168.10.32

192.168.10.33

192.168.10.46

192.168.10.47

3

192.168.10.48

192.168.10.49

192.168.10.62

192.168.10.63

4

192.168.10.64

192.168.10.65

192.168.10.78

192.168.10.79

5

192.168.10.80

192.168.10.81

192.168.10.94

192.168.10.95

6

192.168.10.96

192.168.10.97

192.168.10.110

192.168.10.111

7

192.168.10.112

192.168.10.111

192.168.10.126

192.168.10.127

8

192.168.10.128

192.168.10.129

192.168.10.142

192.168.10.143

9

192.168.10.144

192.168.10.145

192.168.10.158

192.168.10.159

10

192.168.10.160

192.168.10.161

192.168.10.174

192.168.10.175

11

192.168.10.176

192.168.10.177

192.168.10.190

192.168.10.191

12

192.168.10.192

192.168.10.193

192.168.10.206

192.168.10.207

13

192.168.10.208

192.168.10.209

192.168.10.222

192.168.10.223

14

192.168.10.224

192.168.10.225

192.168.10.238

192.168.10.239

15

192.168.10.240

192.168.10.241

192.168.10.254

192.168.10.255

16

        

17

        

Part 5: Network Topology E

The organization has a network address of 172.16.128.0/17 to be divided as illustrated in the following topology. You must choose an addressing scheme that can accommodate the number of networks and hosts in the topology.

Step 1: Determine the number of subnets in Network Topology E.

  1. How many subnets are there? ___________ 9
  2. How many bits should you borrow to create the required number of subnets? _________ 4
  3. How many usable host addresses per subnet are in this addressing scheme? ___________ 2046
  4. What is the new subnet mask in dotted decimal format? _________________________ 255.255.248.0
  5. How many subnets are available for future use? _______________ 7

Step 2: Record the subnet information.

Fill in the following table with the subnet information:

Subnet Number

Subnet Address

First Usable Host Address

Last Usable Host Address

Broadcast Address

0

172.16.128.0

172.16.128.1

172.16.135.254

172.16.135.255

1

172.16.136.0

172.16.136.1

172.16.143.254

172.16.143.255

2

172.16.144.0

172.16.144.1

172.16.151.254

172.16.151.255

3

172.16.152.0

172.16.152.1

172.16.159.254

172.16.159.255

4

172.16.160.0

172.16.160.1

172.16.167.254

172.16.167.255

5

172.16.168.0

172.16.168.1

172.16.175.254

172.16.175.255

6

172.16.176.0

172.16.176.1

172.16.183.254

172.16.183.255

7

172.16.184.0

172.16.184.1

172.16.191.254

172.16.191.255

8

172.16.192.0

172.16.192.1

172.16.199.254

172.16.199.255

9

172.16.200.0

172.16.200.1

172.16.207.254

172.16.207.255

10

172.16.208.0

172.16.208.1

172.16.215.254

172.16.215.255

11

172.16.216.0

172.16.216.1

172.16.223.254

172.16.223.255

12

172.16.224.0

172.16.224.1

172.16.231.254

172.16.231.255

13

172.16.232.0

172.16.232.1

172.16.239.254

172.16.239.255

14

172.16.240.0

172.16.240.1

172.16.247.254

172.16.247.255

15

172.16.248.0

172.16.248.1

172.16.255.254

172.16.255.255

16

        

17

        

Step 3: Assign addresses to network devices in the subnets.

  1. Fill in the following table with IP addresses and subnet masks for the router interfaces:
    Answers Note: These are suggested IP addresses based on using the first 9 subnets from the table above as assigned to each segment.

    Device

    Interface

    IP Address

    Subnet Mask

    R1

    GigabitEthernet 0/0

    172.16.128.1

    255.255.248.0
     

    GigabitEthernet 0/1

    172.16.136.1

    255.255.248.0
     

    Serial 0/0/0

    172.16.144.1

    255.255.248.0
     

    Serial 0/0/1

    172.16.152.1

    255.255.248.0

    R2

    GigabitEthernet 0/0

    172.16.160.1

    255.255.248.0
     

    GigabitEthernet 0/1

    172.16.168.1

    255.255.248.0
     

    Serial 0/0/0

    172.16.144.2

    255.255.248.0
     

    Serial 0/0/1

    172.16.176.1

    255.255.248.0

    R3

    GigabitEthernet 0/0

    172.16.184.1

    255.255.248.0
     

    GigabitEthernet 0/1

    172.16.192.1

    255.255.248.0
     

    Serial 0/0/0

    172.16.152.2

    255.255.248.0
     

    Serial 0/0/1

    172.16.176.2

    255.255.248.0

Reflection

  1. What information is needed when determining an appropriate addressing scheme for a network?______________________________________________________________________________________________________________________________________________________________________________
    Number of networks and hosts are needed when determining an appropriate addressing scheme for a network.
  2. After the subnets are assigned, will all the host addresses be utilized in each subnet?______________________________________________________________________________________________________________________________________________________________________________
    No. For the WAN serial links, only two addresses will be utilized. For the subnets with host PCs, all the addresses can be used in each subnet.