To better understand why we need IP addressing, think of sending a piece of mail from your house to your friend’s house. The envelope has your friend’s address, that’s the destination address. It’s got your return address, that’s the source address.
IP addresses explained
Well, it’s exactly the same thing when we’re sending information in a network. We can send an IP packet between a couple of devices. And that packet is labeled with both a source and destination IP address.
And we’ve also got these devices on the network called routers. And routers, they have the ability to look at that destination IP address and know how to forward that packet. And there are a couple of types of IP addresses.
IP version 4 vs IP version 6
We have IP version 4, we’ve got IP version 6, and they’re commonly referred to simply as IPv4 and IPv6 addresses. Now, IP version 4 addresses, they’re made up of only 32 bits. Now, a bit, that’s a value of either a zero or a one, so that would be two to the power of 32 addresses available for IP version 4.
That might sound like a lot, but we’re actually out. We have run out of blocks of IP version 4 addresses. No longer can you go to your country’s numbering authority and say, “hey, can you give me a block of IPv4 addresses?” Because we’re out. But I got good news. IPv6 comes to the rescue. IP version 6 has a whopping 128 bits.
That means that we can have a unique IPv6 address for every single item we own without fear of ever running out of IPv6 addresses. And going back to our mail analogy, let’s say you asked your friend, “Hey, what’s your address?” And they said, “It’s 13825th Street.” Without any spaces between the numbers. You wouldn’t know if they meant 138 25th Street or if they meant 1382 5th Street.
The role of IP addressing in our networks
There needs to be a diving line to indicate what part of that address refers to the house and what part of that address refers to the street on which that house resides. It’s exactly the same with our IP addresses. They have two parts. There’s the part that refers to the network, and there’s the part that refers to the host on that network.
In IPv4 terminology we call those two parts the network portion and the host portion. It’s a little bit different with IPv6. There we have the prefix portion and the host portion. And that’s a basic look at the role of IP addressing in our networks.