Classful Sub-netting

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24 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Class
-
A is numbered 1through 126. 2^8 = 256 networks,

2^24 = 16,777,216 addresses


Class
-
B is numbered 128 through 191. 2^16 = 65,536 networks,

2^16 = 65,536 addresses



Class
-
C is numbered 192 through 223. 2^24 = 16,777,216 networks,

2^8 = 256 addresses


Class
-
D networks are numbered 224 through 239. Multicast


Class
-
E networks are numbered 240 through 255. Experimental


An IP address is four bytes (octets). Each contains eight bits (total of 32 bits in
length).


IP addresses are given as dotted decimal notation.


IP address classes A, B, and C differentiate in the numbers of networks and host
addresses being utilized by a specific organization.

IPv4 Addresssing



Network & Host address = all 0s: (0.0.0.0) not valid, used during boot




Network address = 0s & Host = #: (0.210.10.6) a valid host address
identifies a host on the current network to other devices.




Network & Host address = all 1s: (255.255.255.255) this is called a
Limited broadcast
, where a message will be received by all hosts on a
local network.




Network # & all 1s on Host: (126.255.255.255) this is called a
Direct
broadcast
, where a message is sent to all computers on a remote
network. Used to find the MAC address of a known host IP address,
Called address resolution (AR)




Network addresses of 127: (127.0.0.1)
loopback

or test address

Reserved Classes



Special IP addresses are known as
Private
, which means
the hosts on the LAN will never directly communicate with
Internet
-
based hosts.




10.x.x.x through 10.255.255.255




172.16.x.x through 172.31.255.255




192.168.x.x through 192.168.255.255

A subnet mask

is used to separate a network number from the host number
in an IP address.
By Changing the Default Subnet Mask, You Split the Host
Number Into a Subnet Number and a Host Number.


Subnet masks are also used to subdivide networks.


1 represents a network and 0 represents a host.

Subnet masks examples Class A, B, & C.


01.0.0.0 255.0.0.0 = no sub
-
netting (default mask)

126.0.0.0 255.255.0.0 = sub
-
netting

others: 255.255.255.0


255.255.255.252


128.100.0.0 255.255.0.0 = no sub
-
netting

191.100.0.0 255.255.255.0 = sub
-
netting
255.255.255.252


192.100.10.0 255.255.255.0 = no sub
-
netting

223.100.10.0 255.255.255.252 = sub
-
netting

MASKS Bits

Subnetting


Classful Subnetting

example:
Class C


IP 192.100.100.10 Mask 255.255.255.248


248 or F8 or 1111 1000 5 extra bits for networking


192.100.100.0 = network default


192.100.100.10 = host


192.100.100.8 = subnet Host 10 belongs to


24 bits in network, 5 added subnet mask bits=29 masks


3 bits for hosts = 2^3= 8 addresses, but only 6 hosts


6 hosts + 1 subnet + 1 broadcast = 8 addresses


256/8= 32 subnets with 8 addresses per network

Table 2.1 Class A Subnet Table


Subnets

Hosts

Mask

Subnet Bits

Host Bits

4


4,194,302

255.192.0.0

2

22

8


2,097,150

255.224.0.0

3

21

16


1,048,574

255.240.0.0

4

20

32


524,286

255.248.0.0

5

19

64


262,142

255.252.0.0

6

18

128


131,070

255.254.0.0

7

17

256


65,534

255.255.0.0

8

16

512


32,766

255.255.128.0

9

15

1,024


16,382

255.255.192.0

10

14

2,048


8,190

255.255.224.0

11

13

4,096


4,094

255.255.240.0

12

12

8,192


2,046

255.255.248.0

13

11

16,384


1,022

255.255.252.0

14

10

32,768


510

255.255.254.0

15

9

65,536


254

255.255.255.0

16

8

131,072


126

255.255.255.128

17

7

262,144


62

255.255.255.192

18

6

524,288


30

255.255.255.224

19

5

1,048,576


14

255.255.255.240

20

4

2,097,152


6

255.255.255.248

21

3

4,194,304


2

255.255.255.252

22

2

Incomplete Class A subnet table

Subnets

Hosts

Mask

Subnet Bits

Host Bits

4

16382

255.255.192.0

2

14

8

8190

255.255.224.0

3

13

16

4094

255.255.240.0

4

12

32

2046

255.255.248.0

5

11

64

1022

255.255.252.0

6

10

128

510

255.255.254.0

7

9

256

254

255.255.255.0

8

8

512

126

255.255.255.128

9

7

1024

62

255.255.255.192

10

6

2048

30

255.255.255.224

11

5

4096

14

255.255.255.240

12

4

8192

6

255.255.255.248

13

3

16384

2

255.255.255.252

14

2

Incomplete Class B subnet table

Subnets

Hosts

Mask

Subnet Bits

Host Bits

4

62

255.255.255.192

2

6

8

30

255.255.255.224

3

5

16

14

255.255.255.240

4

4

32

6

255.255.255.248

5

3

64

2

255.255.255.252

6

2

Incomplete Class C subnet table