Types of IP Addresses – Computer Networks

Before discussing the types of Ip Addresses, let us first understand the role of an IP address in a computer network. Every computer on a computer network has an address. The address is the IP address. A remote machine should use the IP address to reach the device or computer.

For outgoing, each packet has the IP address in the source address of the sending computer. Types of IP addresses have been classified based on communication with each other in a computer network. Communication can be one-to-one, one-to-many, and one to all. In the following, we will describe each type of IP address in detail with an example.

What is the unicast Ip address?

This is the most common type of address. We all have experience working with the unicast IP address type daily. In unicast IP addresses, communication is one-to-one. This means that if a packet is sent with a unicast IP address in the destination, only one host on the network will process it, as a unicast address is unique across the LAN. An IP interface is associated with a Unicast IP address.

An example of a unicast address type is any address of the public webserver. When you type a URL, after DNS lookup, the web server IP address will only process an HTTP request.

Another example can be a LAN computer if an IP packet needs to send from a LAN machine to another machine (e.g., from 192.168.1.20 to 192.168.1.30). The packet is broadcast to all computers on LAN. The computer has the destination IP (192.168.1.30) configured. The others will discard the packet.

Multicast Ip Address:

As the name suggests, in multicast IP address type. There can be one-to-many communication in a scenario where a packet needs to send to a group of remote machines. The network uses a multicast address type in the message’s destination address. Suppose a remote device needs to receive a multicast message. The machine has to subscribe to the multicast address.

For example, if there are ten machines on the LAN. Only five devices have been subscribed to a multicast IP. When a host sends the message to the multicast IP address, only five machines will process the message. Others will silently discard it.

Broadcast Ip Address:

In a Broadcast IP address type, all host receives the same message. This is a one-to-all type of communication. A single host sends the message, and all other hosts on the LAN receive it. A broadcast IP has all 1 in the Host part. For example, if we have a class C type of LAN 192.168.1.1/24, the broadcast IP will be 192.168.1.255. The broadcast address can also be 255.255.255.255.255. When a machine on a network sends the packet to all, it uses 255.255.255.255 in the destination IP address of a message header.

Check Unicast, Multicast, and Broadcast IP addresses:

Till now, we have studied the various types of IP addresses. This section will demonstrate how we can check the different IP addresses of a Linux machine. How can we add/remove the Linux machine to a broadcast IP address?

After login into the machine, we can see the ethernet configuration.

[root@CentOS_6_64-155 ~]# ifconfig -a
eth8 Link encap:Ethernet HWaddr 08:00:27:F4:9A:EA
inet addr:192.168.1.155 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fef4:9aea/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:852793 errors:0 dropped:0 overruns:0 frame:0
TX packets:3536016 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:355151285 (338.6 MiB) TX bytes:5076597166 (4.7 GiB)

Above 192.168.1.155 is the unicast address, and 192.168.1.255 is a Broadcast address. In the fourth line (UP BROADCAST RUNNING MULTICAST), we can see that multicasting is enabled.

How to Check what the multicast address is On Linux?

[root@CentOS_6_64-155 ~]# ip maddr show
1: lo
inet 224.0.0.1
inet6 ff02::1
2: eth8
link 33:33:00:00:02:02
link 33:33:ff:f4:9a:ea
link 01:00:5e:00:00:01
link 33:33:00:00:00:01
inet 224.0.0.1
inet6 ff02::202
inet6 ff02::1:fff4:9aea
inet6 ff02::1

Above the multicast address is 224.0.0.1. If we want to turn off the multicasting, the following is the sequence.

[root@CentOS_6_64-155 ~]# ifconfig eth8 -multicast
[root@CentOS_6_64-155 ~]# ifconfig -a
eth7 Link encap:Ethernet HWaddr 08:00:27:FB:B8:D2
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

eth8 Link encap:Ethernet HWaddr 08:00:27:F4:9A:EA
inet addr:192.168.1.155 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fef4:9aea/64 Scope:Link
UP BROADCAST RUNNING MTU:1500 Metric:1 <--- NO MULTICAST 
RX packets:853912 errors:0 dropped:0 overruns:0 frame:0
TX packets:3537004 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:355260161 (338.8 MiB) TX bytes:5076705082 (4.7 GiB)

After turning off multicast, this machine will not process a packet having a multicast address as the destination IP.

To enable multicasting again.

[root@CentOS_6_64-155 ~]# ifconfig eth8 multicast
[root@CentOS_6_64-155 ~]# ifconfig -a
eth7 Link encap:Ethernet HWaddr 08:00:27:FB:B8:D2
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)