subnetting class B address 172.0.0.0

I have a class B address of 172.0.0.0 and i need 5 subnets out of it.so please help me out with this.thank you.

Hai kampala,

This is ballu. Kampala before giving reply to your query about subnetting i would like to tell you to know how to mail a message in proper format!!!!!!!!!!!!! this keeps you away from MNC's to work in and you no? i really got upset even to give reply to your mail after seeing your mail.I think u will learn how to mail others in good format.

Ok you have 172.0.0.0 network right.

Default network Mask for ur class B network = 255.255.0.0

this mask is only used to identify ur 172.0.0.0 network by a router to route a ip datagram destined to that network(172.0.0.0)

In binary notation= 11111111.11111111.00000000.00000000

Now follow as i told

---

From the above subnet mask u have ---

Number of hosts for the network = 2^16 = 64K approx..

i think u don't want that many hosts for ur network!!!!!!!

So what u and i do subnet the network according to requirment ok:-) fine.

Know consider the last 2 octats from our default netwok mask i.e --


00000000.00000000
(3rd octat) ( 4th octat)

now i write like this(only for ur easy understanding):

10000000.00000000

keep in mind that number of subnets = 2^(number of 1's in last 2 octats) -2.

so as i change MSB to 1, number of subnets = 2^1 = 2-2=0 , not required.

we shall try for other combination i .e 11000000.00000000

now number of subnets = 2^2 = 4-2 = 2 still not required

again we try for other combination(ofcourse i know only to try & try untill i get the things to be done:-)))) i.e 11100000.00000000

now number of subnets = 2^3 = 8 - 2 =6 yes...... i got

now i have 6 subnets in that i use only 5 ....... thats.....

now combining all we get :

11111111.11111111.11100000.0000000(255.255.224.0)

This is the custom subnet mask of ur subneted netwok 172.0.0.0

i.e

172.0.0.0(only for netwok address)

---

172.0.32.0

---

172.0.64.0

---

172.0.96.0

---

172.0.128.0

---

172.0.160.0

---

172.0.192.0
172.0.224.0(only for broadcast for ur subneted network)

And number of hosts per subnet is 2^13.

This how subnet caluculations 'should' be


ok hope u got me!

regards
ballu
done!