VLSM (variable eldest son netmask) is the process of dividing the subnet
The subnet mask and IP address are the IP address of the network address (0&1 = = 0; 1&1 = = 1)
In a nutshell, the IP address and subnet mask are written in binary, and the subnet mask of 1 corresponds to the portion of the IP address that is part of the network
The portion of the subnet mask to 0 corresponds to the portion of the IP address that is the host portion.
Live: The host part is all 0, is the network address of the subnet, can not assign to the PC;
The host part is all 1, is the broadcast address of the subnet, can not assign to the PC
CIDR non-class inter-domain routing, which can be understood as a summary of routes
To divide the subnet step:
A. Number of subnets known to be separated:
1. Figure out the need to borrow the host part of a few bits into the network portion (2 of the n is slightly larger than the number of subnets, N is the number of host bits to borrow)
2. Calculate subnet mask for subnets
3. Reach the subnet segment (network address)
4. The first IP address that can be assigned to a PC under each subnet; the last IP address that can be assigned to the PC; The subnet's broadcast address.
Two. The number of IP addresses required for each subnet is known
1. Calculate the number of bits required for the host part (2 of the n is slightly larger than the number of IP, n is the host bit)
2.32-host bits = = number of network bits
3. Calculate subnet mask for subnets
4. Reach the subnet segment (network address)
5. The first IP address that can be assigned to a PC under each subnet; the last IP address that can be assigned to the PC; The subnet's broadcast address.
The broadcast address of a subnet is the network address of the next subnet-1
The first IP address that can be assigned to a PC, which is the network address of the subnet + 1
Configuration of static routes:
Router (config) #ip Route 10.1.1.0 255.255.255.0 fastethernet 0/0
Or:
Router (config) #ip Route 10.1.1.0 255.255.255.0 1.1.1.1
Comments:
10.1.1.0 255.255.255.0 indicates the target network
FastEthernet 0/0 means to go to the target network from the local interface to send out
1.1.1.1//To the destination network to which IP address (this address must first be reached)
CCNA Course Five