First usable IPv4 address is 172.16.0.1, second usable IPv4 address is 172.16.0.2, third usable IPv4 address is 172.16.0.3. Subnet 1 has its network address 172.16.0.0 with a subnet mask of 255.255.128.0. Visualization of 1-bit subnetting of Class B network 172.16.0.0 with subnet mask 255.255.128.0 is given below. The subnet mask to use for 1-bit subnetting for a Class B network is 255.255.128.0. As mentioned earlier in this lesson, you cannot use network address or directed broadcast address as the IPv4 address for devices inside your network. Two IPv4 addresses are used in each subnet to represent the network address and directed broadcast address (first and last IPv4 addresses in a subnet block). The network 172.16.0.0 is divided into two subnets, each subnet has 32,768 total IPv4 addresses and 32,766 usable IPv4 addresses. That means, we can get two subnets if we do a single bit subnetting on a Class B network. The single bit added to network part from host part in the third octet can have two possible values in third octet, either 0 or 1. If we include one bit from the host part to the network part in the third octet, the default subnet mask of Class B network 255.255.0.0 is changed into 255.255.128.0. You cannot use network address or directed broadcast address as IPv4 address for devices inside your network. If all the bits in the host part are "1", that represents the directed broadcast address.Īll the IPv4 addresses in a subnet block, except network address and directed broadcast address (first and last IPv4 addresses in a subnet block), can be used to configure the devices in your network. If all the bits in the host part are "1" except the last bit, it is the last usable IPv4 address. If all the bits in the host part are "0" except the last bit, it is the first usable IPv4 address.
If all the bits in the host part are "0", that represents the network address.
The binary representation of the above network and its subnet mask are shown in below table. The default format for a Class B IPv4 address is. Remember, the first two octets of a Class B network is used to represent the network and the last two octets are used to represent a host within that network. Network address is 172.16.0.0, first usable IPv4 address is 172.16.0.1, second usable IPv4 address is 172.16.0.2, third usable IPv4 address is 172.16.0.3. Let us try to visualize the unsubnetted Class B network 172.16.0.0 with default subnet mask 255.255.0.0 using below image.
In this Class B Subnetting Tutorial - Part 1, you will learn how to subnet a Class B network. Please visit below links in order to learn IPv4 subnetting completely. You must visit Class C Subnetting Tutorial - Part 1 lesson to understand the basic concepts of subnetting. All the basic concepts about subnetting are explained in Class C Subnetting Tutorial - Part 1 lesson. What i trying to achieve is creating 'Network Ranges' from 'Subnets'. When you talk about a CIDR subnet range, then you talk about ranges like: Unlike 'dan_in-need-of-help' (Topic starter previous post), my approach is to get only 'Network IP' and the 'Broadcast IP' ranges from a subnet, shown as in my example: "Creating 'Network IP' and 'Subnet IP' Ranges from subnets"Īfter reading the following post: Creating IP Ranges from IP Add (Network) and Subnet Mask, I was trying to modify the calculations (calculations taken from previous post) to get 'Network IP' and the 'Broadcast IP' from IP CIDR subnet ranges.