1.0 1010100 10001111100 1011100101011100 101100011101001 1011110100011010 00001010010110010 1001010101100111 1111010101000101 1101001101010011 001010010101010 1010101000110010 010101001011000 110101100011010 11010100001011 001010100110 1001010010 VLSM 17.1.1.0 19.1.10.0 19.1.10.9 19.1.10.1 Variable-Length Mask Workbook Version Version 1.0 Instructor s Edition 17.1.1.0 10.0.1.0
IP Classes Class A 1 17 (Network 17 is reserved for loopback and internal testing) Leading bit pattern 0 00000000.00000000.00000000.00000000 Network... Class B 1 191 Leading bit pattern 10 10000000.00000000.00000000.00000000 Network. Network.. Class C 19 Leading bit pattern 110 11000000.00000000.00000000.00000000 Network. Network. Network. Class D 9 (Reserved for multicast) Class E 0 (Reserved for experimental, used for research) Class A 10.0.0.0 to 10... Class B 17.1.0.0 to 17.1.. Class C 19.1.0.0 to 19.1.. Private Space Class A.0.0.0 Class B..0.0 Class C...0 Default Masks This workbook assumes you already have a background in subnetting. If you don t you may want to consider completing the IP ing and ting Workbook. Produced by: Robb Jones jonesr@careertech.net 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. Instructors (and anyone else for that matter) please do not post the Instructors version on public websites. When you do this your giving everyone else worldwide the answers. Yes, students look for answers this way. It also discourages others; myself included, from posting high quality materials. Inside Cover
What is VLSM Variable Length 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 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 Cisco, OSPF, Dual IS-IS, BGP-, and EIGRP. You need to configure your router for Variable Length Masking by setting up one of these protocols. Then configure the subnet masks of the various interfaces in the IP address interface sub-command. To use supernet you must also configure IP classless routes. The Box Method The box method is the simplest way to visualize the breakdown of a range of addresses into smaller different sized subnets. Start with a square. The whole square is a single subnet comprised of 0 addresses. /...0 s 1 1
Split the box in half and you get two subnets with 1 addresses, 0 1 /...1 1 s s 17 Divide the box into quarters and you get four subnets with addresses, 0 1 /...19 s s 19 17 191 Split each individual square and you get eight subnets with addresses, 0 1 10... s s 1 9 19 9 17 19 191
Split the boxes in half again and you get sixteen subnets with sixteen addresses, 0 1 1 7 1 1 10 1 17 17 /...0 1 s 1 s 1 19 9 19 79 111 0 11 9 17 07 0 0 191 9 The next split gives you thirty two subnets with eight addresses, 0 0 1 1 10 1 7 1 9 7 1 1 17 17 1 1 1 17 1 /9... s s 1 11 19 1 191 7 9 10 19 00 71 79 10 111 199 07 1 9 0 11 10 0 1 0 7 9 119 17 1 7 The last split gives sixty four subnets with four addresses each, You can use these squares in any combination to fit your addressing needs. /0... s s 0 0 1 1 10 1 11 11 19 1 171 1 1 10 1 17 7 1 9 7 1 1 17 17 1 1 1 17 1 19 7 1 9 17 1 179 17 0 0 1 1 10 1 1 11 19 1 191 7 9 10 19 00 7 7 99 107 19 0 7 7 100 10 19 0 71 79 10 111 199 07 1 9 0 11 10 0 1 0 91 11 1 11 19 1 9 11 1 1 0 7 9 119 17 1 7
VLSM ing (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 subnet mask in the boxes below, color or shade the sub-subnets used in the box. This business will be using the class C address 0.10.10.0. Remember to start with your largest groups first. Marketing Department 0 s Research Department s 0.10.10.0/ 0.10.10. Color in the squares used with different shades to highlight each subnet. 0 1 9 9 17
VLSM ing (Sample) Problem 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 19.1.1.0. Remember to start with your largest groups first. WAN #1: 19.1.1./0 Washington D.C. 10 s 19.1.1.0/ WAN #: 19.1.1./0 Baltimore 0 s Frederick 0 s 19.1.1.1/ 19.1.1.19 Color in the squares used with different shades to highlight each sub-subnet. 0 1 19 191 7 1 0 9 17
VLSM ing Problem 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 190.10.10.0. Remember to start with your largest groups first. Dallas. 0 s 19.10.10.0/ WAN #1: 19.10.10.9/0 Ft. Worth s 19.10.10. Color in the squares used with different shades to highlight each sub-subnet. 0 1 9 10 99 100 10 111 11 9 17
VLSM ing Problem 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 0.10..0. Remember to start with your largest groups first. WAN #1: 0.10../0 Corpus Christi s 0.10..19 WAN #: 0.10../0 Houston 10 s Waco 0 s 0.10..0/ 0.10..1/ Color in the squares used with different shades to highlight each sub-subnet. 0 0 1 1 10 1 11 11 19 1 171 1 1 10 1 17 7 1 9 7 1 1 17 17 1 1 1 17 1 19 7 1 9 17 1 179 17 0 0 1 1 10 1 1 11 19 1 191 7 9 10 19 00 7 7 99 107 19 0 7 7 100 10 19 0 71 79 10 111 199 07 1 9 0 11 10 0 1 0 91 11 1 11 19 1 9 11 1 1 0 7 9 119 17 1 7 7
VLSM ing Problem 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 subsubnets used in the box. This company will be using the class C address 19.1.10.0. Remember to start with your largest groups first. WAN #1: 19.1.10.0/0 New York 11 s 19.1.10.0/ 19.1.10./ San Jose WAN #: 19.1.10./0 1 s Fargo s 19.1.10.19 s 19.1.10.1/ Color in the squares used with different shades to highlight each sub-subnet. 0 0 1 1 10 1 11 11 19 1 171 1 1 10 1 17 7 1 9 7 1 1 17 17 1 1 1 17 1 19 7 1 9 17 1 179 17 0 0 1 1 10 1 1 11 19 1 191 7 9 10 19 00 7 7 99 107 19 0 7 7 100 10 19 0 71 79 10 111 199 07 1 9 0 11 10 0 1 0 91 11 1 11 19 1 9 11 1 1 0 7 9 119 17 1 7
VLSM ing Problem 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 subsubnets used in the box. This company will be using the class C address.10.10.0. Remember to start with your largest groups first. WAN #1: WAN #:.10.10.10/0.10.10.1/0 Boston London 1 s s.10.10.11/9.10.10.9/.10.10. s Draw the necessary lines and color in the used squares with different shades to highlight each sub-subnet. 7 s.10.10.0/ 0 1 10 1 9 19 19 191 11 10 111 9 1 1 119 17 9
VLSM ing 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 00.10.70.0. Remember to start with your largest groups first. 00.10.70.0 s Boston s 00.10.70./9 1 s 00.10.70./ 1 s 00.10.70./ Draw the necessary lines and color in the used squares with different shades to highlight each sub-subnet. 0 1 7 1 19 191 71 17 10
VLSM ing Problem 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 19.1..0. Remember to start with your largest groups first. 19.1..1/ WAN #1: 19.1..0/0 s London 1 s 19.1..19 19.1..0/ 9 s 1 s 19.1../ Draw the necessary lines and color in the used squares with different shades to highlight each sub-subnet. 0 1 19 191 0 9 17 11
VLSM ing 1 (Sample) Problem 9 You are developing a school network with the class C address 19.1..0/. There will be three computer labs with 0 computers each that need to be on different sub-subnets. Forty eight classrooms with one computer each that will comprise a single sub-subnet. The administrative office and guidance office contain a total of seven computers which will need to be grouped together. Plan for four more mini labs with six computers to each sub-subnetwork. Divide the network using variable length subnet masks. Complete the information required below. Remember to work from largest to smallest. Broadcast 19.1.. Last Usable 19.1.. First Usable 19.1..1 Mask (/X) / 19.1..0 19.1..9 19.1..17 19.1..19 19.1..17 19.1..1 19.1..191 19.1..199 19.1..07 19.1..9 19.1..1 19.1..1 19.1..17 19.1..1 19.1..190 19.1..19 19.1..0 19.1.. 19.1..97 19.1..19 19.1..11 19.1..177 19.1..1 19.1..19 19.1..01 / /9 /9 /9 /9 19.1.. 19.1..9 19.1..1 19.1..10 19.1..17 19.1..1 19.1..19 19.1..00 1 7 9 10 11 1 1 1
VLSM ing (Sample) Problem 10 You are setting up a small business network with the class C address 0..0.0/. The marketing division will need 1 computers. Research and development needs 7 computers. The reception area will need two computers. Management requires 19 computers. Divide the network using variable length subnet masks. Complete the information required below. Remember to work from largest to smallest. Broadcast 0..0.1 Last Usable 0..0.0 First Usable 0..0.1 Mask (/X) 0..0.0 0..0. 0..0.79 0..0. 0..0. 0..0.7 0..0. 0..0. 0..0. 0..0.1 / /0 0..0. 0..0. 0..0.0 1 7 9 10 11 1 1 1 1
VLSM ing 1 Problem 11 You are setting up a medium sized network with the class C address.7..0/. Marketing needs 9 computers. Research and development needs 110 computers. Bookkeeping will use 1 computers. The reception area will need three computers. Management requires 0 computers. Divide the network using variable length subnet masks. Complete the information required below. Remember to work from largest to smallest. Broadcast.7..17 Last Usable.7..1 First Usable.7..1 Mask (/X) /.7..0.7..191.7...7..9.7..7.7..190.7...7...7...7..19.7..19.7...7..1 / / /9.7..1.7..19.7...7..0 1 7 9 10 11 1 1 1
VLSM ing Problem 1 A shipping company needs to set up its network across several locations. The Denver office needs six computers. The Waco office needs computers. The Fargo office will need five computers. The WAN links between all three locations need to be included in the solution. Using the IP address 19.1.10.0/ divide the network using VLSM. Complete the information required below. Remember to work from largest to smallest. Broadcast 19.1.10.1 Last Usable 19.1.10.0 First Usable 19.1.10.1 Mask (/X) 19.1.10.0 19.1.10.9 19.1.10.7 19.1.10.1 19.1.10. 19.1.10. 19.1.10. 19.1.10.0 19.1.10. 19.1.10. 19.1.10.1 19.1.10.9 19.1.10. /9 /9 /0 /0 19.1.10. 19.1.10.0 19.1.10. 19.1.10. 1 7 9 10 11 1 1 1 1
VLSM ing 1 Problem 1 A new school is being built in the local school district. It will have three computer labs with computers each. There will be classrooms with computers each that need to be on one sub-subnet. The office staff and administrators will need 7 computers. The guidance and attendance office will have computers. Setup the remaining addressing into one sub-subnet for future expansion. The school has been given the address.1.7.0/. Complete the information required below. Remember to work from largest to smallest. Broadcast.1.7.17 Last Usable.1.7.1 First Usable.1.7.1 Mask (/X) /.1.7.0.1.7.19.1.7.191.1.7..1.7.9.1.7.7.1.7..1.7.1.1.7.190.1.7..1.7..1.7..1.7..1.7.19.1.7.11.1.7.19.1.7..1.7.1.1.7.9 / /9 /9.1.7.1.1.7.10.1.7.19.1.7..1.7.0.1.7. 1 7 9 10 11 1 1 1
VLSM ing Problem 1 A local college is setting up a campus wide network. The technology wing will be on its own network address of 19.1.0.0/. The office wing will include 1 computers. There are labs of 0 computers each, labs of 0 computers each and one lab of computers. Complete the information required below. Remember to work from largest to smallest. Broadcast 9.1.0. Last Usable 9.1.0. First Usable 9.1.0.1 Mask (/X) / 19.1.0.0 9.1.0.9 9.1.0.17 9.1.0.19 9.1.0.191 9.1.0. 9.1.0.9 9.1.0.1 9.1.0.1 9.1.0.190 9.1.0. 9.1.0. 9.1.0.97 9.1.0.19 9.1.0.11 9.1.0.19 9.1.0. 9.1.0.9 9.1.0.1 9.1.0.10 9.1.0.19 1 7 9 10 11 1 1 1 17
VLSM ing 1 Problem 1 You are setting up a network for a company in four locations. Location A has computers. Location B has 1 computers. Location C has computers. Location D has computers. There is a WAN connection between all four locations. Complete the information required below using the class C address 19.1.10.0. Remember to work from largest to smallest. Broadcast 19.1.10.17 Last Usable 19.1.10.1 First Usable 19.1.10.1 Mask (/X) / 19.1.10.0 19.1.10.191 19.1.10.07 19.1.10.1 19.1.10.19 19.1.10. 19.1.10.7 19.1.10.190 19.1.10.0 19.1.10.1 19.1.10.1 19.1.10. 19.1.10. 19.1.10.19 19.1.10.19 19.1.10.09 19.1.10.17 19.1.10.1 19.1.10. / / /9 /0 /0 /0 19.1.10.1 19.1.10.19 19.1.10.0 19.1.10.1 19.1.10.0 19.1.10. 1 7 9 10 11 1 1 1
VLSM ing Problem 1 A college dormitory is being remolded. A new network is being installed. There are 0 dorm rooms with two drops each that will be on one sub-subnet. The offices will have drops. The reception desk will have three drops. A small study hall will include 0 drops. Using the IP address 19.1.1.0/ complete the information required below using VLSM. Work from largest to smallest. Broadcast 19.1.1.17 Last Usable 19.1.1.1 First Usable 19.1.1.1 Mask (/X) / 19.1.1.0 19.1.1.19 19.1.1.17 19.1.1.17 19.1.1.1 19.1.1.1 19.1.1.17 19.1.1.19 19.1.1.11 19.1.1.19 /9 /9 19.1.1.1 19.1.1.10 19.1.1.1 1 7 9 10 11 1 1 1 19
VLSM ing 0 Problem 17 You are setting up a business network with the class C address 19.7.10.0/. The marketing division will need 19 computers. Research and development needs 0 computers. The reception area will need four computers. Management requires 1 computers. Divide the network using variable length subnet masks. On the opposite page draw a detailed map of this network. Include the sub-subnet IP addresses for each branch of the network with the subnet mask. One router with four ethernet ports will be used for this network. Broadcast 19.7.10. Last Usable 19.7.10. First Usable 19.7.10.1 Mask (/X) / 19.7.10.0 19.7.10.9 19.7.10.111 19.7.10.119 19.7.10.9 19.7.10.110 19.7.10.11 19.7.10. 19.7.10.97 19.7.10.11 / /9 19.7.10. 19.7.10.9 19.7.10.11 1 7 9 10 11 1 1 1
Problem 17 - Detailed Map Reception Computers 19.7.10.11 to.119 Research & Development 0 Computers 19.7.10 to.......19 Management 1 Computers 19.7.10.9 to.111 Marketing 19 Computers 19.7.10. to.9...0... 1
VLSM ing Problem 1 A small company needs to set up its network across several locations. The New York branch office needs 1 computers. The San Jose office needs computers. The Trinidad office will need 1 computers. The WAN links between all three locations need to be included. Using the IP address 19.0..0/ divide the network using VLSM. On the opposite page draw a detailed map of this network. Include the sub-subnet IP addresses for each branch of the network with the subnet mask. Label the WAN links with the same information. Complete the information required below. Work from largest to smallest. Broadcast 19.0..17 Last Usable 19.0..1 First Usable 19.0..1 Mask (/X) / 19.0..0 19.0..19 19.0..191 19.0..19 19.0..199 19.0..1 19.0..190 19.0..19 19.0..19 19.0..19 19.0..11 19.0..19 19.0..197 /0 /0 19.0..1 19.0..10 19.0..19 19.0..19 1 7 9 10 11 1 1 1
Problem 1 - Detailed Map San Jose Trinidad New York 19.0..19 to.19... 19.0..19 to.199... Computers 19.0..0 to.17...1 Management 1 Computers 19.0..1 to.19... Reception Computers 19.0..10 to.191...
# of Bits Borrowed 7 9 10 11 1 1 1 1 1 17 1 19 0 1 # of Bits Borrowed 7 9 10 11 1 1 1 # of Bits Borrowed Mask.19.0.0..0.0.0.0.0..0.0..0.0..0.0..0.0..1.0..19.0...0..0.0...0...0...0...0...1...19......0...... Mask..19.0...0..0.0...0...0...0...0...1...19......0...... Mask...19......0...... Class A ing Guide Total # of Usable # of s s 1 1 0 1 1 1 10 1,0 1,0,0,0,09,09,19,190 1, 1,,7,7,, 11,07 11,070,1,1,, 1,0,7 1,0,7,097,1,097,10,19,0,19,0 Class B ing Guide Total # of Usable # of s s 1 1 0 1 1 1 10 1,0 1,0,0,0,09,09,19,190 1, 1, Class C ing Guide Total # of Usable # of s s 1 1 0 Total # of s,19,0,097,1 1,0,7,,1 11,07,,7 1,,19,09,0 1,0 1 1 1 Total # of s 1,,19,09,0 1,0 1 1 1 Total # of s 1 Usable # of s,19,0,097,10 1,0,7,,1 11,070,,7 1,,190,09,0 1,0 10 1 0 1 Usable # of s 1,,190,09,0 1,0 10 1 0 1 Usable # of s 0 1
0-17 1-0-1 - -9 9-17 1-19 10-191 19- - Inside Cover VLSM Chart -0 Bits 0- -7-11 1-1 1-19 0- -7-1 - -9 0- -7-1 - -9 0- -7-71 7-7 7-79 0- -7-91 9-9 9-99 100-10 10-107 10-111 11-11 11-119 10-1 1-17 1-11 1-1 1-19 10-1 1-17 1-11 1-1 1-19 10-1 1-17 1-171 17-17 17-179 10-1 1-17 1-191 19-19 19-199 00-0 0-07 0-11 1-1 1-19 0- -7-1 - -9 0- -7-1 - /0... s /9... s /...0 1 s... s /...19 s /...1 1 s /...0 s 0-7 -1 1- -1-9 0-7 - - -71 7-79 0-7 -9 9-10 10-111 11-119 10-17 1-1 1-1 1-11 1-19 1-17 1-17 17-1 1-191 19-199 00-07 0-1 1- -1-9 0-7 - 0-1 1-1 -7 - -79 0-9 9-111 11-17 1-1 1-19 10-17 17-191 19-07 0- -9 0-0- -17 1-191 19-0-17