Chapter 11 Part 2

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Chapter 11 Part 2

• TCP/IP - Subnetting

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Online Subnetting Tutorial

• http//articles.techrepublic.com.com/5100-1035-608
  9187.html (http//www.apsu.edu/lij/07f3770/Handout
  s/subnetting.pdf)
• http//www.ralphb.net/IPSubnet/
• http//compnetworking.about.com/od/workingwithipad
  dresses/a/subnetmask.htm
• http//faculty.ksu.edu.sa/mazyad/Documents/CEN445/
  Tutorial20Cisco20CCNA20Introduction20to20Subn
  etting20(Part203)20-20Printer20Friendly.htm

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Internets IP Address Classes

• When a user wants to connect a private network to
  the Internet he/she can subscribe a set of valid
  Internets network address (public IP address)
  from the ISP or IANA/ARIN
• Valid Internets IP addresses (public IP
  addresses) are divided into 5 classes, although
  only 3 classes are distributed for public use
• Class A IP addresses whose first octet start
  from 1 to 126 AND whose subnet masks are
  255.0.0.0 (only the first octet is the network
  address). Class A IP addresses are used by very
  large networks (e.g., larger ISPs) because these
  IP addresses can support more than 16 million (
  (256 X 256 X 256) 2 ) nodes per network
• Class B IP addresses whose first octet start
  from 128 to 191 AND whose subnet masks are
  255.255.0.0 (the first and the second octet are
  the network address). Class B IP addresses are
  used by large networks (e.g., smaller ISPs,
  larger organizations) because these IP addresses
  can support 65534 nodes per network
• Class C IP addresses whose first octet start
  from 192 to 223 AND whose subnet masks are
  255.255.255.0 (the first octet, the second, and
  the third octet are the network address). Class C
  IP addresses are used by small networks/individual
  computer because these IP addresses can support
  254 nodes per network

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Internets IP Address Classes

• Network address 127.0.0.0 is used for loopback
  testing (e.g., PING application)
• These are IP addresses that have been reserved
  for private IP addresses
• From 10.0.0.0 to 10.255.255.255From 172.16.0.0
  to 172.31.255.255From 192.168.0.0 to
  192.168.255.255
• These addresses can be used in a private network
  or a network connected to the Internet that uses
  a network address translation (NAT)
• If your computer has private IP address, how can
  you find out the public IP address that
  corresponds to your computer?
• www.whatismyip.com

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IP Address Classes

• Practice 1
• ARIN gives you the following network address
  10.0.0.0. Which class this network address
  belongs to? What is the default subnet mask? What
  is the range of the IP addresses that you can use
  in your network? How many computers can you have
  in your network?
• Practice 2
• ARIN gives you the following network address
  150.10.0.0. Which class this network address
  belongs to? What is the default subnet mask? What
  is the range of the IP addresses that you can use
  in your network? How many computers can you have
  in your network?
• Practice 3
• ARIN gives you the following network address
  220.10.10.0. Which class this network address
  belongs to? What is the default subnet mask? What
  is the range of the IP addresses that you can use
  in your network? How many computers can you have
  in your network?

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IP Address Classes

• Practice 4
• ARIN gives you the following network address
  1.0.0.0. Which class this network address belongs
  to? What is the default subnet mask? What is the
  range of the IP addresses that you can use in
  your network? How many computers can you have in
  your network?
• Practice 5
• ARIN gives you the following network address
  130.1.0.0. Which class this network address
  belongs to? What is the default subnet mask? What
  is the range of the IP addresses that you can use
  in your network? How many computers can you have
  in your network?
• Practice 6
• ARIN gives you the following network address
  219.9.9.0. Which class this network address
  belongs to? What is the default subnet mask? What
  is the range of the IP addresses that you can use
  in your network? How many computers can you have
  in your network?

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IP Address Classes

• Practice 7
• ARIN gives you the following network address
  126.0.0.0. Which class this network address
  belongs to? What is the default subnet mask? What
  is the range of the IP addresses that you can use
  in your network? How many computers can you have
  in your network?
• Practice 8
• ARIN gives you the following network address
  191.1.0.0. Which class this network address
  belongs to? What is the default subnet mask? What
  is the range of the IP addresses that you can use
  in your network? How many computers can you have
  in your network?
• Practice 9
• ARIN gives you the following network address
  198.9.9.0. Which class this network address
  belongs to? What is the default subnet mask? What
  is the range of the IP addresses that you can use
  in your network? How many computers can you have
  in your network?

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Subnetting Calculators

• http//www.t1shopper.com/tools/calculate/ip-subnet
  /
• http//www.subnet-calculator.com/subnet.php?net_cl
  assB
• http//www.subnetmask.info/

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Subnetting a network
• Dividing a network into several smaller networks
  (subnetworks)
• These subnetworks are connected to one another by
  using gateways (e.g., routers)
• You do subnetting when
• You have a network
• You want to connect your network to the Internet
  by using valid Internet IP address in each of the
  computers in your network
• Therefore, you subscribe a set of valid Internet
  IP addresses (network address) from
  ARIN/IANA/ISP, AND
• You want to break your network into smaller
  networks (subnetworks). This process is called
  subnetting (i.e., the process of breaking a
  network into smaller networks/subnetworks)

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• You have a network
• You want to connect your network to the Internet
• You subscribe a set of public IP addresses from
  ARIN
• As an example, ARIN gives you 198.3.3.0
  (11000110.00000011.00000011.00000000)
• As a class C address,
• You have to use the first three octet (198.3.3.)
  as the address of your entire network
• You can freely manipulate the last octet (you can
  freely create any combination of 0s and 1s in the
  last octet) to create the host addresses for your
  computers
• There are two options to connect your network to
  the Internet by using the public IP addresses
  that you have

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Option 1. Having a single, undivided giant
  network

What is the subnet?
198.3.3.0 (11000110.00000011.00000011.00000000)
198.3.3.2 (11000110.00000011.00000011.00000010)
198.3.3.253 (11000110.00000011.00000011.11111101)
198.3.3.1 (11000110.00000011.00000011.00000001)
198.3.3.3 (11000110.00000011.00000011.00000011)
198.3.3.254 (11000110.00000011.00000011.11111110)
198.3.3.4 (11000110.00000011.00000011.00000100)
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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Option 2. Breaking the giant network into
  smaller subnetworks

What is the subnet?
198.3.3.0 (11000110.00000011.00000011.00000000)
198.3.3.162 (11000110.00000011.00000011.10100010)
198.3.3.61 (11000110.00000011.00000011.00111101)
198.3.3.161 (11000110.00000011.00000011.10100001)
198.3.3.99 (11000110.00000011.00000011.01100011)
198.3.3.222 (11000110.00000011.00000011.11011110)
198.3.3.196 (11000110.00000011.00000011. 11000100)
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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Benefits of subnetting
• Better network administration Easier to manage
  several smaller networks than one large network
• Troubleshooting one troubleshooting strategy is
  to divide the problem into several smaller parts,
  and diagnose and solve each parts
• Management one management strategy is to divide
  the object into several smaller parts, and assign
  one manager to manage each part
• Better network security
• Avoid the use of packet sniffer
• You can control (filter) the traffic
  entering/leaving a subnet

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• When you subnet a network, you need to assign
  each subnetwork a network address hence, you
  need to create multiple network addresses from
  your public address
• How can you create multiple network addresses
  from your public address?
• By borrowing some bits that you can manipulate to
  be part of the network address, and
• By adding some more bits to the original/default
  subnet mask

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• The goal of subnetting
• You are given a valid Internet network address by
  ARIN/IANA/ISP. This network address is the
  address of your entire network
• If you want to subnet your network, every
  subnetwork must have its own network address
  (subnet address)
• The goal of subnetting is
• To identify how many bits you have to borrow
  (subnet bits) from the bits that you can
  manipulate

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• How to subnet a network?
• Step 1. Identify the maximum number of subnets
  that are required in the network
• Step 2. Identify the number of bits in the valid
  Internets network address given by the IANA that
  can be manipulated (lets call this number of
  bits as MANIP_BITS)
• Class A The last three octets (24 bits) can be
  manipulated
• Class B The last two octets (16 bits) can be
  manipulated
• Class C The last one octets (8 bits) can be
  manipulated
• Step 3. Only for the MANIP_BITS, compute the
  number of subnet bits and host bits to allow the
  maximum number of nodes/subnets required
• Formulas
• Maximum number of subnets 2 subnet bits 2
  
• Step 4. Identify the subnet mask
• MANIP_BITS subnet bits host bits

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Example
• You are a network administrator in a large
  company. IANA/ARIN/ISP has assigned 182.24.0.0 to
  your company. Your company currently has 20
  offices throughout the country
• What is your strategy to subnet the network in
  your company?

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Solution
• We can subnet the network based on geographic
  regions. Based on the 20 20 40 offices, you
  want to create 40 subnets. So, our goal here is
  to identify how many bits we have to borrow to
  allow use to create at least 40 subnet addresses
• Step 1. The maximum number of subnets 40
  subnets
• Step 2. 182.24.0.0 is class B. And therefore, the
  default subnet mask given by the IANA/ARIN/ISP is
  255.255.0.0, or 11111111.11111111.00000000.0000000
  0. And hence, the MANIP_BITS are the last two
  octets (the last 16 bits)

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Solution
• Step 3. You want to find out the number of subnet
  bits required to create 40 subnet addresses
• Formula Maximum number of subnets 2 subnet
  bits 2
• 1 subnet bits Maximum number of subnets 2 1
  2 0 (not enough for 40 subnets)
• 2 subnet bits Maximum number of subnets 2 2
  2 2 (not enough for 40 subnets)
• 3 subnet bits Maximum number of subnets 2 3
  2 6 (not enough for 40 subnets)
• 4 subnet bits Maximum number of subnets 2 4
  2 14 (not enough for 40 subnets)
• 5 subnet bits Maximum number of subnets 2 5
  2 30 (not enough for 40 subnets)
• 6 subnet bits Maximum number of subnets 2 6
  2 62 (ENOUGH for 40 subnets)

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Solution
• Therefore, at least 6 subnet bits are required to
  create a network that has 40 subnets. There are
  22 extra subnets (maximum 62 subnets minus 40
  subnets) available for more new office branches
  in the future
• Step 4. With this configuration, the subnet mask
  for your company is
• MANIP_BITS (the last 16 bits) subnet bits
  (6 bits) host bits (10 bits)
• ?The last 00000000 00000000 11111100 00000000
• Therefore, the subnet mask
• 11111111 11111111 11111100 00000000
  255.255.252.00

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Solution
• What is the maximum number of nodes can be
  connected to a subnet with this configuration
  (using 6 subnet bits)?
• host bits MANIP_BITS - subnet bits 16 bits
  6 bits 10 bits
• Use this formula
• Maximum number of nodes 2 host bits 2
• Maximum number of nodes 2 host bits 2 2 10
  2 1022 nodes

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Solution
• What is the range of network addresses that can
  be used to name the subnetworks in your company?
• RULES
• No subnet bit has ALL 0s
• No subnet bit has ALL 1s
• No host address has ALL 0s
• No host address has ALL 1s
• Original address given by ARIN 182.24.0.0
• 10110110.00011000.00000000.00000000
• Subnet address 0 10110110.00011000.00000000.00000
  000 182.24.0.0
• Subnet address 1 10110110.00011000.00000100.00000
  000 182.24.4.0
• Subnet address 2 10110110.00011000.00001000.00000
  000 182.24.8.0
• Subnet address 3 10110110.00011000.00001100.00000
  000 182.24.12.0
• Subnet address 61 10110110.00011000.11110100.0000
  0000 182.24.244.0
• Subnet address 62 10110110.00011000.11111000.0000
  0000 182.24.248.0
• Subnet address 63 10110110.00011000.11111100.0000
  0000 182.24.252.0

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Subnetting a Network Breaking a Network into
Several Smaller Networks

• Solution
• What is the broadcast address for your companys
  network (i.e., IP address to send a frame to ALL
  computers in the company)?
• Broadcast address Network/subnet address whose
  HOST ADDRESS is ALL 1s
• Companys network address 182.24.0.0 10110110
  00011001 00000000 00000000? broadcast address for
  the companys network 10110110 00011001 11111111
  11111111 182.24.255.255
• Lets suppose that the headquarter network is
  given the first subnetwork address
  10110110.00011000.00000100.00000000 182.24.4.0
  What is the broadcast address for this
  headquarters network (i.e., IP address to send a
  frame to ALL computers in the headquarter office
  only)?
• Broadcast address Network/subnet address whose
  HOST ADDRESS is ALL 1s
• Headquarters network address 182.24.4.0
  10110110.00011000.00000100.00000000 ?
• broadcast address for the headquarters network
  10110110.00011000.00000111.11111111 182.24.7.255

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Subnetting a Network Practice 10

• The next four problems are based on this
  assumption IANA/ARIN/ISP gives IP address
  1.0.0.1 (00000001 00000000 00000000 00000001)
  to company A. This company wants to subnet its
  network into 31 subnetworks.
• What is the subnet mask (in binary format) that
  allows 31 subnetworks and as many nodes in a
  subnetwork as possible?
• 11111111 11111000 00000000 00000000
• 11111111 11111100 00000000 00000000
• 11111111 11111111 11111000 00000000
• 11111111 11111111 11111100 00000000
• What is the maximum number of nodes that can be
  connected to a subnetwork with the subnet mask
  that you identified in the prior problem?
• (24 2)
• (25 2)
• (26 2)
• (218 2)
• What is the broadcast address for company As
  entire network?
• 00000001 00000011 11111111 11111111
• 00000001 00001111 11111111 11111111
• 00000001 00111111 11111111 11111111
• 00000001 11111111 11111111 11111111
• What is the broadcast address for a subnetwork
  whose address is 00000001 10101000 00000000
  00000000?
• 00000001 10101111 11111111 11111111
• 00000001 10101011 11111111 11111111

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Subnetting a Network Practice 11

• The next four problems are based on this
  assumption IANA/ARIN/ISP gives IP address
  144.144.0.1 (10010000 10010000 00000000
  00000001) to company A. This company wants to
  subnet its network into 4 subnetworks.
• What is the subnet mask (in binary format) that
  allows 4 subnetworks and as many nodes in a
  subnetwork as possible?
• 11111111 11111111 11111000 00000000
• 11111111 11111111 11110000 00000000
• 11111111 11111111 11100000 00000000
• 11111111 11111111 11000000 00000000
• What is the maximum number of nodes that can be
  connected to a subnetwork with the subnet mask
  that you identified in the prior problem?
• (22 2)
• (23 2)
• (24 2)
• (213 2)
• What is the broadcast address for company As
  entire network?
• 10010000 10010000 00011111 11111111
• 10010000 10010000 00001111 11111111
• 10010000 10010000 11111111 11111111
• 10010000 10011111 11111111 11111111
• What is the broadcast address for a subnetwork
  whose address is 10010000 10010000 10000000
  00000000?
• 10010000 10010000 10111111 11111111
• 10010000 10010000 10011111 11111111

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