SUBNETTING
Subnetting is process of creating a new Network.
Subnetting mean Mask Manipulation.
Advantage is improve network speed &
performance, reduce network congestion, boost network security & ease administration.
Subnetting formed by 2 way-
Network point of view & Host point of view.
1) Network
point of view
Example- The n/w address given is 16.20.20.0/24 and
there is 8 block n/w in India branch so we have to do subnetting.
16.20.20.0/24 mean 24bit on network side, so we have
subtract 24bit with 32bits.
i.e 32-24=8bits,
mean its host bit.
Number of host is 2^n , i.e 2^8=256
There is 8 block in the n\w , so how many host bits
should be use. i.e 2^3=8
|
128
|
64
|
32
|
16
|
8
|
4
|
2
|
1
|
|
2^7
|
2^6
|
2^5
|
2^4
|
2^3
|
2^2
|
2^1
|
2^0
|
Now new n\w mask become is 16.20.20.0/24+3 i.e
16.20.20.0/27
To find host/network subnet, we have subtract 27bits
with 32bits.
i.e 32-27=5bits , mean 5 host/network
new find subnet mask, if new host bit is 5 then we
have to count from right to left upto 5 block i.e 255.255.255.224/27
|
128
|
192
|
224
|
240
|
248
|
525
|
254
|
255
|
|
128
|
64
|
32
|
16
|
8
|
4
|
2
|
1
|
16.20.20.0/27 is divided 8block
16.20.20.0/27 – 16.20.20.31/27
16.20.20.32/27 – 16.20.20.63/27
16.20.20.64/27 – 16.20.20.95/27
16.20.20.96/27 – 16.20.20.127/27
16.20.20.128/27 – 16.20.20.159/27
16.20.20.160/27 – 16.20.20.191/27
16.20.20.192/27 – 16.20.20.223/27
16.20.20.224/27 – 16.20.20.255/27
2) Subnetting from Host point of view
Take a same IP address 16.20.20.0/24, there is /24
mask in the IP address.
We have to find host bits, so find /24 mask is near
by host.in below table /24 is near is 32.note always take higher value.
|
128
|
64
|
32
|
16
|
8
|
4
|
2
|
1
|
|
2^7
|
2^6
|
2^5
|
2^4
|
2^3
|
2^2
|
2^1
|
2^0
|
Now we have find new mask
Mean 32-5=27 prefix mask of network.
|
128
|
192
|
224
|
240
|
248
|
525
|
254
|
255
|
|
128
|
64
|
32
|
16
|
8
|
4
|
2
|
1
|
The new IP address is 16.20.20.0/27 and
255.255.255.224 subnet
16.20.20.0/27 is divided 8block
16.20.20.0/27 – 16.20.20.31/27
16.20.20.32/27 – 16.20.20.63/27
16.20.20.64/27 – 16.20.20.95/27
16.20.20.96/27 – 16.20.20.127/27
16.20.20.128/27 – 16.20.20.159/27
16.20.20.160/27 – 16.20.20.191/27
16.20.20.192/27 – 16.20.20.223/27
16.20.20.224/27 – 16.20.20.255/27
nice!!
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