Are you online? Of course you are! And that’s how you are reading this blog right now. Would you like to know how this is possible? This series is all about what it takes to be online and access internet!

Hey peeps, so far we’ve only discussed about the existence of IPv6 addressing. In this blog, we’ll see how IPv4 and IPv6 will coexist in networks, structure of IPv6 address and the benefits of IPv6 addressing over IPv4. Let’s go!

Routers as Gateways

The router provides a gateway through which the hosts on one network can communicate with the host on other networks. The IPv4 address assigned to the interface identifies which local network is connected directly to it. Every host on a network must use the router as a gateway to other networks. Hence, it is necessary that each host must know the IPv4 address of the router interface connected to the network. This address is known as the “default gateway address”. It can be either statically configured or received dynamically by DHCP.

Routers as boundaries between Networks

The router acts as a DHCP server for the internal hosts attached to it. Most DHCP servers are configured to assign private IPv4 addresses to the internal hosts, rather than internet routable public addresses. This ensures that the internal network is not directly accessible from the internet.

Photo by Misha Feshchak on Unsplash

Network Address Translation (NAT)

The router receives a public address from the ISP and it provides private addresses to local network clients. But the private addresses are not allowed on the internet. Hence, a process is needed to translate the Private IPv4 address to Public IPv4 address that is used on the internet. This process is reversed for incoming packets. The internet will only route the Public IPv4 addresses. NAT is used The Private IP Networks are:

  • (Subnet mask
  • (Subnet mask
  • (Subnet mask

Although each hosts on the internal network has a unique private IPv4 address, the hosts share the single internet-routable address assigned to the wireless router.

The router has a reference table like structure that has the Private IPv4 addresses of the hosts and their corresponding Public IPv4 addresses on the internet.

In this blog, we have discussed about how router is used as a gateway, boundaries and discussed about an important operation, NAT. I’ll catch you up in the next blog about IPv6.

Until then, Stay connected!!

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Sudarshan S

Tech enthusiast | Developer | Programmer | Machine learning | Data science | Cybersecurity