Subnetting and Supernetting Modules (SSM)


SSM:   SOLD       



This material is intended to explain to students about how to calculate the network mask in each class and implement it in packet tracer. The goal is to;

  • Students can calculate netmasks and subnetmasks in all IP classes.
  • Students can design computer networks using network configurations that have subnet masks.

Supernetting is a technique of combining several networks into a supernetwork. This is usually done by class C which requires a larger host. The masking for supernetting is called a supernetmask.

CIDR (Classless Interdomain Routing) is a technique to reduce the number of network addresses in the routing table by using a supernet mask and the smallest network address of the supernet represents the other network address members.

Subnetting is a technique used to break down the network ID owned by an IP into several other subnetwork IDs with a smaller number of network members.

Masking is the process of extracting a physical network address from an IP Address. This masking is a 32-bit binary number that is used for;

  • distinguish network ID and host ID
  • shows the location of a host, whether it is on a local network or an external network.

The masking used for subnetting is called a subnet mask. For example, suppose we will divide the allocation of class B IP 132.92.121.1 into a small network of 254.... more details are in the module, please download.

Subnetting Method & Calculation Techniques

Objective:

  1. Perform network sharing
  2. Performing subnetting calculations

Budiyono et al (2005) explained that supernetting is combining several networks into a supernetwork. This is usually done by class C which requires a larger host. Masking for supernetting is called supernetmask.

Substance:

  1. CIDR (Classless Interdomain Routing)
  2. Masking
  3. How to Determine Subnet Mask
  4. Benefits of Subnetting
  5. SUBNETTING ON CLASS A IP ADDRESS
  6. SUBNETTING ON CLASS B IP ADDRESS
  7. SUBNETTING ON CLASS C IP ADDRESS
  8. Table Conversation
  9. Exercises and Discussion

1. CIDR (Classless Interdomain Routing)

CIDR (Classless Interdomain Routing) is a technique to reduce the number of network addresses in the routing table by using a supernet mask and the smallest network address of the supernet represents the other network address members, while Subnetting is a technique or method used to break down the network ID owned by an IP into several other subnetwork IDs with a smaller number of network members.

2. Masking

Masking is the process of extracting a physical network address from an IP Address. This masking is a 32-bit binary number that is used for:

  • Differentiating between network ID and host ID
  • Shows the location of a host, whether it is on a local network or an external network.

The mask used for subnetting is called a subnet mask, for example:

For example, we will divide the allocation of class B IP 132.92.121.1 into a small network of 254.

3. How to Determine the Subnet Mask

The way to determine the subnet mask is as follows;

  1. Converting the number of networks needed into binary numbers. A class B network can be converted into 255 class C networks. The number 255 when represented in binary is 11111111.
  2. Calculating the number of bits needed to represent the number 255 in binary requires 8 bits. This is how many bits are needed by the subnet ID. The number of bits of the current host ID is the number of bits of the old host ID minus the number of bits needed by the subnet ID, so we have to set 0 for all new host IDs, while the network ID is set to 1 for all to produce the subnet mask that will be used.
132.92.121.1 kemudian di AND kan dengan subnet mask tersebut,
132.92.121.1 = 10000100.01011100.10000111.00000001
255.255.255.0 = 11111111.11111111.11111111.00000000 AND
1000o100.01011100.10000111.00000000

With this new subnet mask, the IP Address 132.92.121.1 is read as:

  • Network ID: 132.92.121
  • Host ID: 1

Note: For convenience, you can use the calculator and IP Subnet Calculator.

4. Benefits of Subnetting

Wirawanto (2013) in the Computer Network Report stated that Subnetting is an effort/process to break down a network with a large number of hosts into several networks with fewer hosts. The uses of subnetting are:

  • To determine network ID limits in a subnet
  • Increase the number of networks (LAN)
  • Reducing the number of hosts in a network
  • To reduce the level of congestion (interference / collision) of data traffic in a network.

Subnetting calculations can be done in two ways, namely:

  • Binary (slower)
  • Special (faster)

IP address writing is generally 192.168.1.2, but sometimes it is written as 192.168.1.2/24, meaning that the IP address 192.168.1.2 with a subnet mask of 255.255.255.0. The question is why is that?, well the answer is so /24 is taken from the calculation that 24 bits of the subnet mask are shrouded in binary 1, or in other words, the subnet mask is: 11111111.11111111.11111111.00000000 (255.255.255.0). This concept is called CIDR (Classless Inter-Domain Routing) which was first introduced in 1992 by IEFT.

Essentially all questions about subnetting will revolve around these four issues:

  • Number of Subnets
  • Number of Hosts per Subnet
  • Subnet Block
  • Host-Broadcast Address.

5. Subnetting on Class A IP Addresses

Example of subnetting case with a NETWORK ADDRESS 10.0.0.0/16.

Class A in octets 2, 3 and 4 (the last octet), then the subnet mask that can be used for class A subnetting is all subnet masks from CIDR / 8 to / 30.

Analysis:

10.0.0.0 means class A, with Subnet Mask /16 means 11111111.11111111.000000000.00000000 (255.255.0.0)

Calculation:

  1. Number of Subnets = 28 = 256 subnets
  2. Number of Hosts per Subnet =216-- 2 = 65534 hosts
  3. Subnet Block = 256 -- 255 = 1, so the complete subnets are 0, 1, 2, 3, 4, etc.

6. Subnetting on IP Address Cass B

Example of Subnetting case with a NETWORK ADDRESS 172.16.0.0/18 and 172.16.0.0/25

Based on the subnet block, CIDR /17 to /24 is exactly the same as Class C subnetting, only we enter the subnet block directly into the third octet, not like Class C which is "played" in the fourth octet. While CIDR /25 to /30 (multiples) subnet blocks we "play" in the fourth octet, but after the third octet is finished, it moves forward (counter) from 0, 1, 2, 3, etc.

Example 1: Network address 172.16.0.0/18

Analysis:

172.16.0.0 means class B, with Subnet Mask /18 means 11111111.11111111.11000000.00000000 (255.255.192.0).

Calculation:

  1. Number of Subnets = 2x, where x is the number of binary 1s in the last 2 octets. So the number of Subnets is 22 = 4 subnets
  2. Number of Hosts per Subnet = 2y -- 2, where y is the inverse of x, which is the number of binary 0s in the last 2 octets. So the number of hosts per subnet is 214 -- 2 = 16,382 hosts
  3. Subnet Block = 256 -- 192 = 64. The next subnets are 64 + 64 = 128 and 128 + 64 = 192, so the complete subnets are 0, 64, 128, 192.

Example 2: Network address 172.16.0.0/25

Analysis:

172.16.0.0 means class B, with Subnet Mask /25 means 11111111.11111111.11111111.10000000 (255.255.255.128).

Calculation:

  1. Number of Subnets = 2x, where x is the number of binary 1s in the last 2 octets. So the number of Subnets is 29 = 512 subnets
  2. Number of Hosts per Subnet = 2y -- 2, where y is the inverse of x, which is the number of binary 0s in the last 2 octets. So the number of hosts per subnet is 27 -- 2 = 126 hosts
  3. Subnet Block = 256 -- 128 = 128, so the full subnet is 0.128.

7. Subnetting on Class C IP Address

Analysis:

192.168.1.0 means class C with Subnet Mask /26 means 11111111.11111111.11111111.11000000 (255.255.255.192).

Calculation:

  1. Number of Subnets = 2x, where x is the number of binary 1s in the last 2 octets of the subnet mask (the last 2 octets for class B and the last 3 octets for class A). So the number of Subnets is 22 = 4 subnets.
  2. Number of Hosts per Subnet = 2y -- 2, where y is the inverse of x, which is the number of binary 0s in the last octet of the subnet mask. So the number of hosts per subnet is 26 -- 2 = 62 hosts.
  3. Subnet Block = 256 -- 192 (last octet value of subnet mask) = 64. The next subnets are 64 + 64 = 128 and 128 + 64 = 192, so the complete subnets are 0, 64, 128, 192.
| Subnet Mask   | Wild-Card Mask | Prefix |
|---------------|----------------|--------|
| 255.0.0.0     | 0.255.255.255  | /8     |
| 255.128.0.0   | 0.127.255.255  | /9     |
| 255.192.0.0   | 0.63.255.255   | /10    |
| 255.224.0.0   | 0.31.255.255   | /11    |
| 255.240.0.0   | 0.15.255.255   | /12    |
| 255.248.0.0   | 0.7.255.255    | /13    |
| 255.252.0.0   | 0.3.255.255    | /14    |
| 255.254.0.0   | 0.1.255.255    | /15    |
| 255.255.0.0   | 0.0.255.255    | /16    |
| 255.255.128.0 | 0.0.127.255    | /17    |
| 255.255.192.0 | 0.0.63.255     | /18    |
| 255.255.224.0 | 0.0.31.255     | /19    |
| 255.255.240.0 | 0.0.15.255     | /20    |
| 255.255.248.0 | 0.0.7.255      | /21    |
| 255.255.252.0 | 0.0.3.255      | /22    |
| 255.255.254.0 | 0.0.1.255      | /23    |
| 255.255.255.0 | 0.0.0.255      | /24    |

8. Table Conversation

9. Exercises and Discussion

Experimental Procedure

  1. Download and install the Packet Tracer application
  2. Windows:  http://www.packettracernetwork.com/
  3. Linux: <ftp://rpmfind.net/linux/opensuse/update/12.2/i586/libopenssl1_0_0-1.0.1e-2.8.1.i586.rpm>

Exercise

Split the network as needed. Given that there are 94 hosts on each network.

Resolution / Discussion

1. Find Host Number

2h ≥ 94
h = 7
Banyaknya host = 2n -- 2
                           = 27 -- 2
                           = 128 -- 2
                           = 126 host / jaringan yang disediakan

2. Find Network Numbers

Angka host = nilai basis - angka network

7 = 8 -- n
n = 8 -- 7
n = 1\
Banyaknya jaringan = 2n
                                 = 21
                                 = jadi banyaknya jaringan adalah 2

3. Find the Perfix Number

Angka perfix = 24 + angka network
                      = 24 + 1
                      = 25

192.168.2.0 /25

Subnet mask : 255.255.255.128
11111111 . 11111111 . 11111111 . 10000000\
Range 0  : 192.168.2 .0 - 192.168.2 .127
Subnet 0 : 192.168.2 .1 - 192.168.2 .126
Range 1  : 192.168.2 .128 - 192.168.2 .255
Subnet 1 : 192.168.2 .129 - 192.168.2 .254

Conclusion:

Subnetting is needed for efficiency and optimization of a network.

Source:

Eko Yunianto, S.Kom || NPP : 201430052

Bibliography

  • Budiyono et al., 2005, "Computer Network Practical Materials Installation & Configuration of Internet Networks - Internet", Telkom Technology College, Bandung
  • ftp://ftp-eng.cisco.com/cons/isp/documents/CIDRGuide.doc accessed April 8, 2014 03:55:44
  • Wirawanto, Rizki, 2013, Computer Network Practical Report Module 6, Kuningan University, West Java
  • www.twc-us.com/FILES/VLSM.doc accessed April 8, 2014 03:55:40
  • DOWNLOAD MODUL
  • DOWNLOAD REPORT PART 1
  • DOWNLOAD REPORT PART 2

Practical Steps

For example, we will create a division of a class C network into two subnets. Then we can do the following calculation.  2An >= 2 -> 2^1 >=2 , so that n = 1 So the subnet in binary is  11111111.11111111.11111111.10000000 or if converted into decimal becomes  255.255.255.128 (can be seen in the binary conversion table).

Now to find out the number of usable IPs for each host in each subnet, perform the following operations:

256 — 128 = 128

NB: 256 = sum of the range from 0 — 255

128 = value of the last field of the new subnet
128 = used as the range for the subnet

The result 128 shows the usable IP for each new subnet mask.

The following is a list of all subnets for class C subnet masks 255.255.255 128

Subnet 0, 192.168.1.0 - 192.168. 1. 127

  • network id = 192.168.1.0
  • broadcast = 192.168.1.127

1st subnet: 192.168.1.128 - 192.168. 1.255

  • network id = 192.168.1.128
  • broadcast = 192.168.1.255

Network Topology

1). Setting IP Server

2). Setting DHCP Server

3). Perform steps 1 and 2 according to the subnet mask on the second network (192.168.1.128/128)
4). Perform Basic Router settings to connect networks 1 and 2
5). Set the client computer to DHCP

6). Perform connection testing using simple PDU and web browser.

7). Done

Bibliography

Budiyono et al., 2005, "Computer Network Practical Material Installation & Configuration of Intranet-Internet Networks, Telkom Technology College, Bandung ftp://ftp-eng.cisco.com/cons/isp/documents/CIDRGuide.doc accessed April 8, 2014 03:55:40
Wirawanto, Rizki, 2013, Computer Network Practical Report Module 6, Kuningan University, West Java www.twc-us.com/FILESNLSM.doc accessed April 8, 2014 03:55:40


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