6
Page 1 of 6 Variable Length Subnet Mask (VLSM) Use IP 192.168.55.0 /24
Page 1 of 6
Variable Length Subnet Mask
(VLSM)
Use IP
192.168.55.0 /24
Page 2 of 6
We Have: - 64 32 16 8 4 2 1
1- 90 Hosts. 1 0 1 1 0 1 0 = 7 Bits (Block).
2- 23 Hosts. 1 0 1 1 1 = 5 Bits (Block).
3- 7 Hosts. 1 1 1 = 3 Bits (Block).
4- 2 Hosts. = 3 Hosts 1 1 = 2 Bits (Block).
5- 2 Hosts. = 3 Hosts 1 1 = 2 Bits (Block).
Because we have 2 Hosts So we will add 1 Host because that
called bounded number that is ( 1,2,4,8,16,32,64)
Now We Will Calculate VLSM Start with Largest Number of
Hosts:-
1- 90 Hosts
Represent in 7 Bits
192.168.55.0 /24
255.255.255.0000 0000
+
255.255.255.1000 0000
___________________
255.255.255.128 /25 New Subnet Mask
Incremental = 128.
192.168.55.0 /25 Network _Id For 90 Hosts
192.168.55.128 /25 we will use it for the other
Network (23 Hosts).
Page 3 of 6
2- 23 Hosts
Represent in 5 Bits
192.168.55.128 /25
255.255.255.1000 0000
+
255.255.255.1110 0000
___________________
255.255.255.224 /27 New Subnet Mask
Incremental = 32.
192.168.55.128 /27 Network _Id For 23 Hosts
192.168.55.160 /27 we will use it for the other
Network (7 Hosts).
3- 7 Hosts
Represent in 3 Bits
192.168.55.160 /27
255.255.255.1110 0000
+
255.255.255.1111 1000
___________________
255.255.255.248 /29 New Subnet Mask
Incremental = 8.
192.168.55.160 /29 Network _Id For 7 Hosts
192.168.55.168 /29 we will use it for the other
Network (2 Hosts).
Page 4 of 6
4- 2 Hosts
Represent in 2 Bits
192.168.55.168 /29
255.255.255.1111 1000
+
255.255.255.1111 1100
___________________
255.255.255.252 /30 New Subnet Mask
Incremental = 4.
192.168.55.168 /30 Network _Id For 2 Hosts
192.168.55.172 /30 we will use it for the other
Network (2 Hosts).
5- 2 Hosts
Represent in 2 Bits
192.168.55.172 /30
255.255.255.1111 1100
+
255.255.255.1111 1100
___________________
255.255.255.252 /30 New Subnet Mask
Incremental = 4.
192.168.55.172 /30 Network _Id For 2 Hosts
192.168.55.176 /30 we will use it for the other
Network.
Page 5 of 6
Commands for each Router:-
1- Router 2 (On the left)
Configure terminal
Router rip
Version 2
Network 192.168.55.0
Network 192.168.55.160
Network 192.168.55.172
2- Router 1 (On the middle)
Configure terminal
Router rip
Version 2
Network 192.168.55.0
Network 192.168.55.0
Network 192.168.55.168
Network 192.168.55.172
Page 6 of 6
3- Router 0 (On the right)
Configure terminal
Router rip
Version 2
Network 192.168.55.0
Network 192.168.55.128
Network 192.168.55.168
{Note}
ال البذ مه إعذاد Serial Portانخاص بال IPعنذ إعذاد ال
Clock Rate في كمInterface متصم ببعضو بحيث يكون انرقم
نيو ىو Default و ال Serial Cableكم طرف مهمتساوى في
كما موضح بانصوره . 00666
