Vlsm variable length subnet mask workbook version 1.0

1010100 10001111100

1011100101011100 101100011101001 1011110100011010 00001010010110010 1001010101100111 1111010101000101 1101001101010011 001010010101010 1010101000110010 010101001011000 110101100011010 11010100001011 001010100110 100101001001.0172.16.1.0 192.168.10.0

01 0

10.250.1.0 172.31.15.0

192.168.10.96 192.168.10.126

Version 1.0

VLSM Workbook

Variable-Length Subnet Mask

Version 2.0

Student Name:

IP Address Classes

Class A 1 – 127 (Network 127 is reserved for loopback and internal testing) Leading bit pattern 0 00000000.00000000.00000000.00000000

Class B 128 – 191 Leading bit pattern 10 10000000.00000000.00000000.00000000

Class C 192 – 223 Leading bit pattern 110 11000000.00000000.00000000.00000000

Class D 224 – 239 (Reserved for multicast)

Class E 240 – 255 (Reserved for experimental, used for research)

Private Address Space

Class A 10.0.0.0 to 10.255.255.255

Class B 172.16.0.0 to 172.31.255.255

Class C 192.168.0.0 to 192.168.255.255

Default Subnet Masks

Class A 255.0.0.0

Class B 255.255.0.0

Class C 255.255.255.0

Network . Host . Host . Host

Network . Network . Host . Host

Network . Network . Network . Host

Inside Cover

This workbook assumes 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 taking the 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

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 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.

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 is supported 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 sub- command.

Benefits of VLSM

Allows efficient use of address space Allows the use of multiple subnet mask lengths Breaks up 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.

1

Classful Subnetting Example

When you’re subnetting an IP address for a network you have two options: 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 two address each so you are wasting 28 usable addresses in each of the serial subnet ranges.

192.168.1.0 192.168.1.32 192.168.1.64 192.168.1.96 192.168.1.128 192.168.1.160 192.168.1.192 192.168.1.224

192.168.1.31 192.168.1.63 192.168.1.95 192.168.1.127 192.168.1.159 192.168.1.191 192.168.1.223 192.168.1.255

to to to to to to to to

/27 255.255.255.224

32 Hosts 8 Subnets

Marketing 25 Hosts Records

12 Hosts

Research 30 Hosts

IP Address: 192.168.1.0

0

255

128

63 64 192

191

32

31

95

96 159

223

224

160

127

The Box Method for visualizing subnets

/27 /27 /27 /27 /27 /27 /27 /27

2

Classful Subnet Ranges

Classless Subnetting Example

Classless addressing allows you to use different subnet masks and create subnets tailored to the number of users in each subnetwork. There are fewer wasted IP addresses using smaller subnets.

In this example you need at total of five subnets, two containing 30 hosts, one containing 12 hosts, and two serial connections that only require two usable addresses each.

By adjusting the subnet masks you can cut your address usage by almost half in this example. This type of subnetting requires a network protocol which will support it such as: RIP version 2, EIGRP, OSPF, or BGP.

Marketing 25 Hosts Records

12 Hosts

Research 30 Hosts

IP Address: 192.168.1.0

0

255

79

128

63 64

32

31 96

83

87

80

184 12795

88

192.168.1.0 192.168.1.32 192.168.1.64 192.168.1.80 192.168.1.84 192.168.1.88 192.168.1.96 192.168.1.128

192.168.1.31 192.168.1.63 192.168.1.79 192.168.1.82 192.168.1.87 192.168.1.95 192.168.1.127 192.168.1.255

to to to to to to to to

/27 /27 /28 /30 /30 /29 /27 /25

3

The Box Method for visualizing subnets

Classless Subnet Ranges

/24 255.255.255.0

256 Hosts 1 Subnet

Start with a square. The whole square is a single subnet comprised of 256 addresses.

Visualizing Subnets Using The Box Method

The box method is a simple way to visualize the breakdown of subnets and addresses into smaller sizes. By shading or coloring in the boxes you can easily break up your subnets without overlapping your addresses. You adjust each subnet to the correct size needed.

/25 255.255.255.128

128 Hosts 2 Subnets

/26 255.255.255.192

64 Hosts 4 Subnets

4

Split the box in half and you get two subnets with 128 addresses.

Divide the box into quarters and you get four subnets with 64 addresses.

5

/27 255.255.255.224

32 Hosts 8 Subnets

Split each individual square and you get eight subnets with 32 addresses.

/30 255.255.255.252

4 Hosts 64 Subnets

/29 255.255.255.248

8 Hosts 32 Subnets

/28 255.255.255.240

16 Hosts 16 Subnets

Split the boxes in half again and you get sixteen subnets with sixteen addresses.

The next split gives you thirty two subnets with eight addresses.

The last split gives sixty four subnets with four addresses each.

Color in the squares used with different shades to highlight each subnet.

VLSM Addressing Box Method

(Sample) Problem 1

Using the network diagram and information given create an addressing scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the box. This business will be using the class C address 220.10.10.0. Re- member to start with your largest groups first.

Marketing Department

60 Hosts

LAN Address:

220.10.10.0/26

Research Department

28 Hosts

LAN Address:

220.10.10.64/27

0

255127

128

63 64

95

96

6

VLSM Addressing Box Method

(Sample) Problem 2

Using the network diagram and information given create an addressing scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the box. This company will be using the class C address 192.168.16.0. Re- member to start with your largest groups first.

Washington D.C. 120 Hosts

Frederick 20 Hosts

Baltimore 60 Hosts

0

255127

128

192 191

223

LAN Address:

192.168.16.0/25

LAN Address:

192.168.16.192/27 LAN Address:

192.168.16.128/26

WAN Address #1:

192.168.16.224/30 WAN Address #2:192.168.16.228/30

227

239231

224 232

228

240

Color in the squares used with different shades to highlight each subnet.

7

8

VLSM Addressing Box Method

Problem 3 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the box. This company will be using the class C address 190.10.10.0. Re- member to start with your largest groups first.

Dallas 60 Hosts

Ft. Worth 25 Hosts

LAN Address:

LAN Address:

WAN Address #1:

Color in the squares used with different shades to highlight each subnet.

0

255

128

63 64

95

96

99

103 111

127

104

100

112

VLSM Addressing Box Method

Problem 4 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the box. This company will be using the class C address 220.108.38.0. Re- member to start with your largest groups first.

Corpus Christi 25 Hosts

Waco 50 Hosts

Houston 120 Hosts

LAN Address:

LAN Address:LAN Address:

WAN Address #1: WAN Address #2:

Color in the squares used with different shades to highlight each subnet.

9

0 12832 160

15 4739 175167135 1437

11 4335 171163131 1393

27 5951 187179147 15519

31 6355 191183151 15923

75 10799 235227195 20367

79 111103 239231199 20771

91 123115 251243211 21983

95 127119 255247215 22387

408 136 168

4 13236 1644412 140 172

16 14448 1765624 152 184

20 14852 1806028 156 188

64 19296 22410472 200 232

68 196100 22810876 204 236

80 208112 24012088 216 248

84 212116 24412492 220 252

10

VLSM Addressing Box Method

Problem 5 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the box. This company will be using the class C address 192.168.10.0. Remember to start with your largest groups first.

New York 115 Hosts

Fargo 23 Hosts

LAN Address:

LAN Address:

WAN Address #2:

Color in the squares used with different shades to highlight each subnet.

San Jose

12 Hosts

48 Hosts

LAN Address:

LAN Address:

WAN Address #1:

0 12832 160

15 4739 175167135 1437

11 4335 171163131 1393

27 5951 187179147 15519

31 6355 191183151 15923

75 10799 235227195 20367

79 111103 239231199 20771

91 123115 251243211 21983

95 127119 255247215 22387

408 136 168

4 13236 1644412 140 172

16 14448 1765624 152 184

20 14852 1806028 156 188

64 19296 22410472 200 232

68 196100 22810876 204 236

80 208112 24012088 216 248

84 212116 24412492 220 252

VLSM Addressing Box Method

Problem 6 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the box. This company will be using the class C address 222.10.150.0. Remember to start with your largest groups first.

Boston

LAN Address:

WAN Address #1:

Draw the necessary lines and color in the used squares with different shades to highlight each subnet.

11

London

WAN Address #2:

6 Hosts

12 Hosts

LAN Address:

24 Hosts 37 Hosts

LAN Address:

LAN Address:

0

255

128

63 64 192

191

32

31

95

96 159

223

224

160

127

Toyko

12

VLSM Addressing Box Method

Problem 7 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and subnet mask in the boxes below, color or shade the sub-subnets used in the box. This company will be using the class C address 200.150.70.0. Remember to start with your largest groups first.

Draw the necessary lines and color in the used squares with different shades to highlight each subnet.

Boston 2

LAN Address:

6 Hosts

12 Hosts

LAN Address:

LAN Address:

14 Hosts

LAN Address:

25 Hosts

0

255127

128

63 64 192

191

Serial Address:

Boston 1

VLSM Addressing Box Method

Problem 8 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and subnet mask in the boxes below, color or shade the sub-subnets used in the box. This company will be using the class C address 192.168.24.0. Remember to start with your largest groups first.

LAN Address:

Draw the necessary lines and color in the used squares with different shades to highlight each subnet.

13

London

WAN Address #2:

18 Hosts

LAN Address:

95 Hosts 12 Hosts

LAN Address:

LAN Address:

0

34 Hosts

255

WAN Address #1:

Paris

New York

/24 255.255.255.0

256 Hosts 1 Subnet

Start with a circle. The whole circle is a single subnet comprised of 256 addresses.

Visualizing Subnets Using The Circle Method

The circle method is another method used to visualize the breakdown of subnets and addresses into smaller sizes. By shading or coloring in the different sections of the circle you can easily break up your subnets without overlapping your addresses. You adjust each subnet to the correct size needed.

/25 255.255.255.128

128 Hosts 2 Subnets

/26 255.255.255.192

64 Hosts 4 Subnets

Split the circle in half and you get two subnets with 128 addresses.

Divide the circle into quarters and you get four subnets with 64 addresses.

.0

.127.128

.255

.0

.127.128

.255

.63

.64.191 .192

14

/27 255.255.255.224

32 Hosts 8 Subnets

Split each quarter and you get eight subnets with 32 addresses.

/30 255.255.255.252

4 Hosts 64 Subnets

/29 255.255.255.248

8 Hosts 32 Subnets

/28 255.255.255.240

16 Hosts 16 Subnets

Split the boxes in half again and you get sixteen subnets with sixteen addresses.

The next split gives you thirty two subnets with eight addresses.

The last split gives sixty four subnets with four addresses each.

.0

.127.128

.255

.63

.64.191 .192

.31 .32

.95 .96.159

.160

.223 .224

.0

.31

.15 .16

.64

.63

.48 .47

.32

.111 .96

.95

.80 .79

.112 .127

.176

.224 .223

.192

.208 .207

.191

.175

.159

.143

.160

.144

.128

.255 .239

.240

15

.0 -

.7

.24 - .

31.8 -

.1 5

.1 6 -

.2 3

.64 - .71

.56 - .63 .48 - .

55 .40

- .47 .32

- . 39

.104 - .111 .96 - .103

.88 - .95

.80 - .87

.72 - .79

.112 - .119

.120 - .127

.176 - .183

.22 4 -

.2 31

.21 6 -

.22 3

.192 - .199

.208 - .2

15

.200 - .2 07

.184 - .191

.168. - 175

.152 - .159

.136 - .143

.160 - .167 .144 - .151

.128 - .135

.2 48

- .2

55

.2 32

- . 23

9

.2 40

- . 24

7

.0 - .

3

.24 - .

27

.8 -

.1 1

.1 6 -

.1 9

.64 - .67

.56 - .59

.48 - . 51

.40 - .4

3 .32

- . 35

.104 - .107 .96 - .99

.88 - .91

.80 - .83

.72 - .75

.112 - .115

.120 - .123 .176 - .179

.22 4 -

.2 27

.21 6 -

.21 9

.192 - .195

.208 - .21

1

.200 - .2 03

.184 - .187

.168. - 171

.152 - .155 .136 - .139

.160 - .163

.144 - .147

.128 - .131

.2 48

- .2

51

.2 32

- . 23

5

.2 40

- . 24

3

.4 - .

7

.1 2

- . 15

.2 0 -

.2 3

.28 - .

31

.36 - .

39

.44 - .47

.52 - .55

.60 - .63

.68 - .71

.76 - .79

.84 - .87 .92 - .95

.100 - .103

.108 - .111

.116 - .119

.124 - .127

.132 - .135

.140 - .143 .148 - .151

.156 - .159

.164 - .167

.172. - 175

.180 - .183

.188 - .191

.196 - .199

.204 - .207

.21 2 - .

215 .22

0 - .2

23 .2 28

- . 23

1

.2 36

- . 23

9

.2 44

- .2

47

.2 52

- .2

55

16

Color in the necessary circle sections used with different shades to highlight each subnet.

VLSM Addressing Circle Method

(Sample) Problem 9

Using the network diagram and information given create an addressing scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the circle below, color or shade the sub-subnets used. This business will be using the class C address 220.10.10.0. Remember to start with your largest groups first.

Marketing Department

60 Hosts

LAN Address:

220.10.10.0/26

Research Department

28 Hosts

LAN Address:

220.10.10.64/27

.0.255

.127.128

.96

.63

.95

.64

17

VLSM Addressing Circle Method

(Sample) Problem 10

Using the network diagram and information given create an addressing scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the circle below, color or shade the sub-subnets used. This company will be using the class C address 192.168.16.0. Remember to start with your largest groups first.

Washington D.C. 120 Hosts

Frederick 20 Hosts

Baltimore 60 Hosts

LAN Address:

192.168.16.0/25

LAN Address:

192.168.16.192/27 LAN Address:

192.168.16.128/26

WAN Address #1:

192.168.16.224/30 WAN Address #2:192.168.16.228/30

Color in the necessary circle sections used with different shades to highlight each subnet.

.255.240

.2 32

- .2

39

.0

.127

.191

.128

.223

.192

.22 4 -

.2 27

.22 8 -

.2 31

.0

18

Color in the necessary circle sections used with different shades to highlight each subnet.

VLSM Addressing Circle Method

Problem 11 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the circle below, color or shade the sub-subnets used. This business will be using the class C address 200.20.20.0. Remember to start with your largest groups first.

Marketing Department

50 Hosts

LAN Address:

Department 25 Hosts

LAN Address:

Marketing Department 100 Hosts

LAN Address:

.224

.255

.127

.191

.128

.223

.192

19

VLSM Addressing Circle Method

Problem 12 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the circle below, color or shade the sub-subnets used. This company will be using the class C address 199.55.70.0. Remember to start with your largest groups first.

Color in the necessary circle sections used with different shades to highlight each subnet.

LAN Address:

New York

21 Hosts

LAN Address:

115 Hosts 8 Hosts

LAN Address:

LAN Address:

12 Hosts

WAN Address #1:

Boston .0

- .3

.24 - .

27

.8 -

.1 1

.1 6 -

.1 9

.64 - .67

.56 - .59

.48 - . 51

.40 - .4

3.3 2 -

.3 5

.104 - .107 .96 - .99

.88 - .91

.80 - .83

.72 - .75

.112 - .115

.120 - .123

.176 - .179

.22 4 -

.2 27

.21 6 -

.21 9

.192 - .195

.208 - .21

1

.200 - .2 03

.184 - .187

.168. - 171

.152 - .155

.136 - .139

.160 - .163 .144 - .147

.128 - .131

.2 48

- .2

51

.23 2 -

.2 35

.2 40

- . 24

3

.4 -

.7

.1 2

- . 15

.2 0 -

.2 3

.28 - .

31

.36 - .

39

.44 - .47

.52 - .55

.60 - .63

.68 - .71

.76 - .79 .84 - .87.92 - .95

.100 - .103

.108 - .111

.116 - .119

.124 - .127

.132 - .135 .140 - .143

.148 - .151 .156 - .159

.164 - .167

.172. - 175

.180 - .183

.188 - .191

.196 - .199

.204 - .207

.212 - .2

15 .2 20

- .2 23 .22

8 - .2

31

.2 36

- . 23

9

.2 44

- . 24

7

.2 52

- .2

55

20

VLSM Addressing Circle Method

Problem 13 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the circle below, color or shade the sub-subnets used. This company will be using the class C address 200.150.70.0. Remember to start with your largest groups first.

New Delhi

LAN Address:

22 Hosts

5 Hosts

LAN Address:

LAN Address:

7 Hosts

LAN Address:

35 Hosts

Serial Address:

Mumbai

12Hosts LAN Address:

Color in the necessary circle sections used with different shades to highlight each subnet.

.0 -

.3

.24 - .

27

.8 -

.1 1

.1 6 -

.1 9

.64 - .67

.56 - .59

.48 - . 51

.40 - .4

3.3 2 -

.3 5

.104 - .107 .96 - .99

.88 - .91

.80 - .83

.72 - .75

.112 - .115

.120 - .123

.176 - .179

.22 4 -

.2 27

.21 6 -

.21 9

.192 - .195

.208 - .21

1

.200 - .2 03

.184 - .187

.168. - 171

.152 - .155

.136 - .139

.160 - .163 .144 - .147

.128 - .131

.2 48

- .2

51

.23 2 -

.2 35

.2 40

- . 24

3

.4 -

.7

.1 2

- . 15

.2 0 -

.2 3

.28 - .

31

.36 - .

39

.44 - .47

.52 - .55

.60 - .63

.68 - .71

.76 - .79 .84 - .87.92 - .95

.100 - .103

.108 - .111

.116 - .119

.124 - .127

.132 - .135 .140 - .143

.148 - .151 .156 - .159

.164 - .167

.172. - 175

.180 - .183

.188 - .191

.196 - .199

.204 - .207

.212 - .2

15 .2 20

- .2 23 .22

8 - .2

31

.2 36

- . 23

9

.2 44

- . 24

7

.2 52

- .2

55

21

VLSM Addressing Circle Method

Problem 14 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the circle below, color or shade the sub-subnets used. This company will be using the class C address 210.10.10.0. Remember to start with your largest groups first. LAN Address:

Hong Kong

WAN Address #2:

18 Hosts

LAN Address:

95 Hosts 12 Hosts

LAN Address:

LAN Address:

27 Hosts

WAN Address #1:

Shanghai

Beijing

18 Hosts

Draw the necessary lines and color in the used circle sections with different shades to highlight each subnet.

.0

.127

.191

.128

.223

.192

.224 .31 .32

.63

.64

.95 .96.159

.160

.255

22

VLSM Addressing Circle Method

Problem 15 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the circle. This company will be using the class C address 192.168.150.0. Remember to start with your largest groups first.

Vienna 15 Hosts

Frankfurt 30 Hosts

LAN Address:

LAN Address:

WAN Address #2:

Prague 12 Hosts

48 Hosts

LAN Address:

WAN Address #1:

Draw the necessary lines and color in the used circle sections with different shades to highlight each subnet.

Venice 23 Hosts

48 Hosts

LAN Address:

WAN Address #3: LAN Address:

.0

.127

.191

.128

.192 .63 .64

.255

23

VLSM Addressing Circle Method

Problem 16 Using the network diagram and information given create an addressing

scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the circle. This company will be using the class C address 195.75.23.0. Remember to start with your largest groups first.

San Juan

LAN Address:

WAN Address #1:

Draw the necessary lines and color in the used circle sections with different shades to highlight each subnet.

Kingston

WAN Address #2:

6 Hosts

12 Hosts

LAN Address:

24 Hosts 37 Hosts

LAN Address:

LAN Address:

Guatemala City

San Jose

12 Hosts

LAN Address:

13 Hosts

WAN Address #3

.0

.127.128

.255

Visualizing Subnets Using a VLSM Chart

The VLSM chart is the third method used to visualize the breakdown of subnets and addresses into smaller sizes. By shading or coloring in the boxes you can easily break up your subnets without overlapping your addresses. You can adjust each sub-subnet to the correct size needed.

24

Marketing Department

60 Hosts

LAN Address:

220.10.10.0/26

Research Department

28 Hosts

LAN Address:

220.10.10.64/27

VLSM Addressing VLSM Chart Method

(Sample) Problem 17

Using the network diagram and information given create an addressing scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the chart. This business will be using the class C address 220.10.10.0. Remember to start with your largest groups first.

0-127

128-255

0-3 4-7 8-11

12-15 16-19 20-23 24-27 28-31 32-35 36-39 40-43 44-47 48-51 52-55 56-59 60-63 64-67 68-71 72-75 76-79 80-83 84-87 88-91 92-95 96-99

100-103 104-107 108-111 112-115 116-119 120-123 124-127 128-131 132-135 136-139 140-143 144-147 148-151 152-155 156-159 160-163 164-167 168-171 172-175 176-179 180-183 184-187 188-191 192-195 196-199 200-203 204-207 208-211 212-215 216-219 220-223 224-227 228-231 232-235 236-239 240-243 244-247 248-251 252-255

/30 255.255.255.252

4 Hosts

/29 255.255.255.248

8 Hosts

/28 255.255.255.240

16 Hosts

/27 255.255.255.224

32 Hosts

/26 255.255.255.192

64 Hosts

/25 255.255.255.128

128 Hosts

/24 255.255.255.0

256 Hosts

0-7

8-15

16-23

24-31

32-39

40-47

48-55

56-63

64-71

72-79

80-87

88-95

96-103

104-111

112-119

120-127

128-135

136-143

144-151

152-159

16-167

168-175

176-183

184-191

192-199

200-207

208-215

216-223

224-231

232-239

240-247

248-255

0-15

16-31

32-47

48-63

64-79

80-95

96-111

112-127

128-143

144-159

160-175

176-191

192-207

208-223

224-239

240-255

0-63

64-127

128-191

192-255

0 - 255

0-31

32-63

64-95

96-127

128-159

160-191

192-223

224-255

25

Class C Addresses VLSM Chart 24-30 Bits (4th octet)

26

VLSM Addressing VLSM Chart Method

(Sample) Problem 18

Using the network diagram and information given create an address- ing scheme which utilizes variable-length subnet masks. Show the subnet address and CIDR in the boxes below, color or shade the sub-subnets used in the chart. This company will be using the class C address 192.168.16.0. Re- member to start with your largest groups first.

Washington D.C. 120 Hosts

Frederick 20 Hosts

Baltimore 60 Hosts

LAN Address:

192.168.16.0/25

LAN Address:

192.168.16.192/27 LAN Address:

192.168.16.128/26

WAN Address #1:

192.168.16.224/30 WAN Address #2:192.168.16.228/30

27

0-127

128-255

0-3 4-7 8-11

12-15 16-19 20-23 24-27 28-31 32-35 36-39 40-43 44-47 48-51 52-55 56-59 60-63 64-67 68-71 72-75 76-79 80-83 84-87 88-91 92-95 96-99

100-103 104-107 108-111 112-115 116-119 120-123 124-127 128-131 132-135 136-139 140-143 144-147 148-151 152-155 156-159 160-163 164-167 168-171 172-175 176-179 180-183 184-187 188-191 192-195 196-199 200-203 204-207 208-211 212-215 216-219 220-223 224-227 228-231 232-235 236-239 240-243 244-247 248-251 252-255