My IP address
My subnet address
Destination IP adress
Example:
My IP adress = 192.168.10.12
My subnet mask = 255.255.255.0
Dest IP address = 192.168.11.47
ANDing process If my subent mask is 255, then the number above and below the subnet have to match in order to connect
Where there is a zero in my subnet address, I dont care
Since the third part dosent match they cant match
outcome 1: I talk to you
outcome 2: I sed my frame to my default gateway/router
Default Ipv4 subne masks
(Also known as classful subneting)
Class A subnet masks 255.0.0.0 - 32 bits total, 8 network, 24 hosts
`16 million addresses
Class B 255.255.0.0 - 32 bits total, 16 network, 16 hosts
`65k addresses
Class C 255.255.255.0 ` 32 bits, 24 networ, 8 hosts
My IP address example: 192.168.40.37
255.0.0.0 - Class A
network portion : 192
host portion: 168.40.37
Why you might use one subnet mask over the other:
to narrow down the amount of users wolfphram alpha google
enable
configure terminal
interface gigabitEthernet 0/0
ip adress 192.168.10.1 255.255.255.0
no shutdown
But what about more specific netowrk requirments?
You need a network that needs 28 users
You could use a class C netork, but its not very efficent
Subnetting - Classless subnetting
(use wolfram for all of this ^2)
255.255.255.0
This subnet actually represents bianary numbers
32 1s or 0s
111111111111111111111111100000000
255.255.0.0
111111111111111100000000000000000
Subnet mask - string of 1s followed by a string of 0s
192.168.16.9
255.255.255.0
192.168.16.4
1100 0000 1010 0000 0001 0000 0000 1001
1111 1111 1111 1111 1111 1111 0000 0000
1100 0000 1010 0000 0001 0000 0000 0100
Remember, the numbers above and bellow 192.168.40.0
255.255.255.0
1100 0000 1010 0000 0010 1000 0000 0000
1111 1111 1111 1111 1111 1111 0000 0000
But what if I give this bit to the network?
1111 1111 1111 1111 1111 1111 1000 0000
Now its 128. Howabaout another eh?
1111 1111 1111 1111 1111 1111 1100 0000
Now its 64
1111 1111 1111 1111 1111 1111 1110 0000 -> 255.255.255.244 when converted back
128 + 64 + 32 = 224 is part the new ip address we lose 2 ip address in every netowrk we have the
network ID:
IP address that represents a network
Ip address where all HOSTs bits are 0s
192.168.40. 000 0 0000 -> 192.168.40.0
network broadcast: IP address where all HOST bits are set to 1s
192.168.40. 000 1 1111
192.168.40.31 -> network broadcast
192.168.40.0 255.255.255.0
You need to have 3 networks
255.255.255. 1000 0000
1
0 000 0000 -> 0
1 111 1111 :: 128
0 0 00 0000 -> 0
0 0 00 0000 -> 64