1 / 16

Subnetting

Subnetting. John McGarvey LYIT. Index. IP addressing classes Subnet masking Subnetting Exercises ANDing function. Intro Subnetting. IP addressing Classes within IP Class A - 16,777,214 (2 24 - 2) - Governments - start with 0

yuma
Download Presentation

Subnetting

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Subnetting John McGarvey LYIT

  2. Index • IP addressing classes • Subnet masking • Subnetting • Exercises • ANDing function

  3. Intro Subnetting • IP addressing • Classes within IP • Class A - 16,777,214 (224 - 2) - Governments - start with 0 • Class B - 65,534(216 -2) - Medium-size companies - start with 10 • Class C - 254 (28 -2) - all other entities - start with 110 • Class D - reserved for use by Multicast services provided by The internet Group Management Group (IGMP) - start with 1110 • Multicast broadcasts allow IP datagrams to be sent to specific groups that belong to a multicast group • Class E- Not in use or only used for testing and development Reserved for future use - start with 11110

  4. IP Addressing 193.32.2.0 • We need to use bits from the host part of an IP address to create subnets • The number of bits depend on the number of subnets needed for that company Network Host

  5. Subnet Mask • Properties of the Subnet mask are • 32 bits • in binary format • expressed as 4 octets • Defined from left to right • Used by internetworking devices to find out what type of network/ subnetwork is installed/used by a company

  6. Subnet Mask • “ The most misunderstood part of IP addressing” • DO not introduce above in a class ! • Subnet Masks are used to make it easy to distinguish between network and host address • example a class B network not subnetted • 130.12.0.0 - IP address • 255.255.0.0 - Subnet mask • N NH H All network bits assigned to 1 • 11111111.11111111.0.0

  7. Subnet Mask • Default Subnet masks • Class A - 255.0.0.0 • Class B - 255.255.0.0 • Class C - 255.255.255.0 • What happens when we use subnetting?

  8. Subnetting • Why ? - Because using natural address masks are not efficient - too large • Reduces the size of the network, which in turn makes it easier to manage and troubleshoot • Breaking up the address space into useable subnets • Process involves borrowing bits from the host part of the address to create a larger network address • Subnetting is done by network administrator

  9. Subnetting Exercise A • Example of Subnetting • The Network Administrator of LYIT receives new Network address 132.8.0.0 • LYIT has 8 departments • A number of questions that need to be answered are:- • 1. What class is the network address? • 2. How many subnets are needed? • 3. How many bits are borrowed from the host part of the address? • 4. How many subnets are defined and how many of these are useable? • 5. What is the default subnet mask? • 6. What is the new customised subnet mask? • 7. What is the decimal value of each subnet? • 8. What is the total number of hosts?

  10. Subnetting • 1. What class is the network address? Ans. It’s a Class B address • 2. How many subnets are needed? Ans. 8 departments so we need 8 subnets • 3.How many bits need to be borrowed? Ans. 4 bits to provide 14 subnets • 4. How many subnets are defined and how many of these are useable? Ans. 2 x 2 x 2 x 2 = 16 are defined 16 - 2 = 14 are useable • 5. What is the default subnet mask? Ans. 255.255.0.0 or 11111111.11111111.0.0

  11. Subnetting • 6. What is the new customised subnet mask? Ans. 128+64+32+16 = 1111 starting with the leftmost significant bit value of the leftmost host octet 255.255.240.0 or 11111111.11111111.11110000.00000000 • 7. What is the decimal value of each subnet? Ans. 138.8.0.0 10001010.00001000.00010000.00000001 to and including 10001010.00001000.11100000.11111110 138.8.16.1 - 138.8.31.254 - subnet 1 138.8.32.1 - 138.8.47.254 - subnet 2 138.8.48.1 - 138.8.63.254 - subnet 3 etc 138.8.208.1 - 138.8.223.254 - subnet 14 Network, Subnet and Host

  12. Subnetting • 8. What is the total number of hosts? 14 subnets The remainder of the host part of the address is 12 bits we have 16-4 borrowed = 12 bits left for hosts each subnet can have 2 to the power of 16 -2 hosts • 212 -2 = 4094 • -2 for network and broadcast addresses • 14 useable subnets x 4094 useable host addresses • Ans. 57316

  13. Subnetting Exercise B • What would be the case if the Network Administrator were given the following network address 192.12.8.0, and the number of departments were 7. • 1. What class is the network address? • 2. How many subnets are needed? • 3. How many bits are borrowed from the host part of the address? • 4. How many subnets are defined and how many of these are useable? • 5. What is the default subnet mask? • 6. What is the new customised subnet mask? • 7. What is the decimal value of each subnet? • 8. What is the total number of hosts?

  14. Subnetting • 1. What class is the network address? • Class C as it is above 191 • 2. How many subnets are needed? • 7 subnets -why not use just 3 bits • 3. How many bits are borrowed from the host part of the address? • 4 bits are needed • 4. How many subnets are defined and how many of these are useable? • 2 x 2 x 2 x 2 = 16 are defined - 16 - 2 = 14 are useable • 5. What is the default subnet mask? • 255.255.255.0 class C • 6. What is the new customised subnet mask? • 255.255.255.240

  15. Subnetting • 7. What is the decimal value of each subnet? • 192.12.8.0 • 11000000.0001100.00001000.00010000 • to and including • 11000000.0001100.00001000.11111110 • 192.12.8.16 - 192.12.8.31 - subnet 1 • 192.12.8.32 - 192.12.8.47 - subnet 2 • 192.12.8.48 - 192.12.8.63 - subnet 3 • etc • 192.12.8.208 - 192.8.223 - subnet 14 8. What is the total number of hosts? • 14 x (24 -2 = 14) • 14 x 14 = 196 Network, Subnet and Host

  16. ANDing function • In order to route a data packet, the router must first determine the destination network/subnet address by performing a logical AND using the destination host's IP address and the subnet mask. The result will be the network/subnet address.

More Related