An internet gateway is essentially a ‘node’ that allows two different networks to communicate. Thanks to these gateways, we can communicate and transfer data.
Gateways can come in different forms depending on what function they will be used for. For example, a router is a good example of a hardware gate. But you can also have software that acts as gateways to allow internet traffic between different computers.
The main difference between an internet gateway and a NAT gateway is that an internet gateway is designed to allow instances with public IP addresses to access the internet. In contrast, an AWS NAT (or network address translation) gateway allows networking instances with no public IP address to access the internet.
What is an internet gateway?
When we refer to an internet gateway, we are talking about something that allows us to connect to the internet.
So at home, this internet gateway is your internet service provider who allows you to access the internet through its network via a router.
For example, in a commercial business scenario, an internal network may allow the company to communicate and work within the premises, which you will most likely access through software.
However, when we approach the topic of an internet gateway versus an AWS NAT gateway, we are referring to the AWS VPC (or Amazon Web Service Virtual Private Cloud), an online data storage solution.
Grants access to data on the AWS VPC
So in this context, the Internet Gateway is there to allow you to access data stored on the virtual private cloud via the internet.
Likewise, it allows resources stored within the Amazon VPC to have internet access, making it go both ways.
This can be very important if you have processes within your amazon VPC that need to collect data from another server or network that it is not directly linked to and, therefore, needs to access it through the internet.
Common gateway type for VPCs
Most users will pick this widely available gateway type to allow communication between their VPC and the internet.
Supports IPv4 and IPv6 traffic
IPv4 stands for Internet Protocol Version 4 and is one of the most widely used protocols. It’s a series of four eight-bit binary numbers that allows your VPC to communicate with a specific address. For example, the IP address of Google is 126.96.36.199. Using those numbers, your network can access that website.
IPv6, on the other hand, is less commonly used but is the most recent version of the Internet Protocol. This was developed to underestimate the popularity of the internet, so the need for additional addresses arose. IPv6 addresses this by allowing for more numbers in their IP addresses.
But sometimes IPv6 is not always supported simply due to being less common. But in this case, both protocol types are supported by an internet gateway.
Only one internet gateway with a VPC
Although an internet gateway does not cause any issues due to bandwidth constraints, potentially making your data unavailable due to high traffic. You can only have 1 Internet Gateway active per amazon AWS account.
This means all inbound and outbound internet traffic will use that same internet gateway, and there is no possibility of having multiples on a single AWS cloud account.
The standard Internet Gateway comes with no additional charge to your account. This is because there are very few instances where someone wouldn’t want to utilize an internet connection with their VPC.
What is a NAT gateway?
While the NAT instance works similarly to the internet gateway, allowing services within the VPC to connect to the internet, they also support IPv4 and IPV6 traffic.
The primary difference is that it only works in a single direction, allowing services within the VPC to connect to external services. However, those external services will not be able to initiate a connection with those services internal to your amazon web services VPC.
Network Address Translation gateways support some additional protocols, including TCP, UDP, and ICMP, allowing you to use both a connection-orientated and a connectionless protocol for faster connection speeds and efficiency.
Unlike the Internet Gateway, which is not Availability Zone specific, the NAT device is created within an availability zone and utilizes redundancy within that zone.
Unless you create multiple NAT gateways within each availability zone, if resources are sharing a NAT instance that is being accessed by various zones and one of those zones goes down, then all resources, regardless of availability zone, will also go down.
To create a VPS that is Availability Zone-independent you will need to develop individual NAT gateways for each zone.
Unlike the internet gateway, which is free, a NAT gateway is charged both for each available hour and also per gigabyte of data that it processes—making it a considerably more expensive choice than the standard internet gateway.
What is the difference between an internet gateway and a NAT gateway?
While there are similarities between an internet gateway and a NAT gateway, there are some key differences that you should be aware of to know which one is best suited for your needs.
Additional protocol support
While both support IPv4 and IPv6 traffic, there are some additional protocols that a NAT gateway supports, including TCP, UDP, and ICMP, which provide additional functionality and increased connection speeds.
Availability zone specific
The standard internet gateway is not Availability Zone specific; the NAT gateway is Availability Zone specific and will require separate NAT gateways if you want to make your VPS Availability Zone independent.
While the standard internet gateway is free, the NAT gateway carries an additional charge per hour, which is also charged per gigabyte of transferred data.
One way vs. both ways
The standard internet gateway allows you to connect to an outside service and enable resources on the internet to initiate a connection back into your subnet.
On the other hand, the NAT gateway only allows the outbound connection, so instances within the private subnet can connect to services outside the amazon web services VPC. Still, those services cannot initiate a connection back.
Internet gateway vs. NAT gateway: Are they the same?
While they do share similarities in that they allow your VPS to connect to outside services using IPv4 and IPv6 traffic.
The NAT gateway will not allow those outside services to establish a connection back into your private subnet. However, this carries an additional charge, making it a more expensive option than the standard internet gateway.