Glossary: IP address, DS-Lite, CGNAT and more

What is an IP address?

An IP address is the number used to reach devices and connections on the internet. Every data packet carries the sender’s and the recipient’s address so that replies find their way back. There are local addresses inside your own network and public addresses on the internet, and two versions: IPv4 and IPv6.

At home, your laptop gets a local address such as 192.168.x.x. Websites never see it; they see the public address your router uses to take every device in the household online.

What is a public IP address – and what does “home IP” mean?

A public IP address is the address a connection uses on the internet. Websites see it with every request and use it to work out, among other things, which country you’re in. Your home IP is the public IP address of your internet connection at home – the address websites see when you browse from home.

On many residential lines, the provider assigns the public address and may change it from time to time. When you travel, you normally use the address of the hotel, café or mobile provider. Our guide to using your home IP abroad explains how to take yours with you.

What’s the difference between IPv4 and IPv6?

IPv4 and IPv6 are two versions of the Internet Protocol. IPv4 addresses are 32 bits long, IPv6 addresses 128 bits. Because IPv4 addresses are scarce, many connections now get IPv6 but no longer have their own public IPv4 address. Both versions run side by side on the internet.

The IPv6 specification increases the address size from 32 to 128 bits. You can still reach websites that only speak IPv4: your provider then forwards IPv4 traffic over shared addresses, for example via DS-Lite or CGNAT.

What is DS-Lite?

DS-Lite (Dual-Stack Lite) means your line gets an IPv6 connection but no public IPv4 address of its own. IPv4 traffic is wrapped in IPv6, tunnelled to your provider and sent out to the internet there, using a public IPv4 address shared by many customers.

That’s how the RFC 6333 standard describes it: address translation (NAT) happens centrally at your provider, not in your router at home. Connections you start yourself work normally. Incoming connections are the problem: anyone trying to reach your line over IPv4 – your own VPN server, for example – ends up at your provider, not at your router. More in our guide to DS-Lite.

What is CGNAT?

CGNAT (carrier-grade NAT) means your internet provider translates the addresses of many customers centrally onto a small number of public IPv4 addresses. Your router then gets no public IPv4 address. Connections you start yourself work, but connections from the internet can’t reach your line directly over IPv4.

A dedicated address range is reserved for the link between the provider and the customer’s router: 100.64.0.0/10, i.e. 100.64.x.x to 100.127.x.x (RFC 6598). If your router shows an IPv4 address from this range, your line is very likely behind CGNAT. DS-Lite also relies on this kind of NAT at the provider.

What is a VPN?

A VPN (virtual private network) is an encrypted connection between two points on the internet, often called a tunnel. Others on the same network can’t read the data inside it. Which IP address websites see depends on where the tunnel ends: at a VPN provider, at your company or at your home.

• A provider’s VPN app: The tunnel ends in a data centre. Websites see the provider’s IP address.
• Work VPN: The tunnel ends in the company network and gives you access to internal systems.
• VPN to your home: The tunnel ends at your own line. Websites see your home IP, and you can reach devices on your home network.

A VPN protects the route, not your identity: websites still recognise you by your logins, cookies and account details.

What is WireGuard?

WireGuard is a VPN protocol – a set of rules for building an encrypted tunnel. Its developers describe it as simple, fast and modern, using state-of-the-art cryptography. Each end of the tunnel is identified by a public key. WireGuard runs on Linux, Windows, macOS, iOS and Android.

You’ll find the details on the WireGuard project site. Homvoya uses WireGuard for the tunnel between the home box, the relay server and the travel box. For the GL.iNet Opal, the manufacturer states up to 65 Mbit/s with WireGuard and up to 12 Mbit/s with OpenVPN (both lab figures).

What is a travel router?

A travel router is a small, portable router. It connects to the local network – the hotel Wi-Fi or a LAN cable, for example – and creates its own Wi-Fi network for your devices. Many models can also build a VPN tunnel, which then covers every device connected to them.

The advantage: you set up the unfamiliar network once on the router, including any hotel login page. Your laptop, phone or TV then join the travel router’s familiar Wi-Fi, without extra software. The travel box in the Homvoya Kit is a travel router of this kind (GL.iNet Opal, GL-SFT1200).

What is a relay server?

A relay server is an intermediary server on the internet that two devices each connect to on their own initiative. It passes the traffic between them. You need one when neither side can be reached directly from the internet, for example on DS-Lite or CGNAT lines.

Homvoya’s relay server is located in the EU, and the tunnel is encrypted with WireGuard. The content of your traffic isn’t logged; connection data is kept for 7 days for operation and abuse prevention. Websites don’t see the relay server’s address but your home IP, because your traffic only goes out to the internet at home.

What do upload and download mean?

Download is the speed at which data reaches you from the internet; upload is the speed at which your connection sends data out. Both are given in Mbit/s. On many lines, upload is much lower than download. When you use your home IP on the road, it’s mainly the upload at home that counts.

When you browse through your home connection while away, your line at home downloads the data and sends it on to you via its upload. That upload is the ceiling for your speed on the road; for Homvoya we recommend at least 10 Mbit/s. You’ll find your figure in your contract or with a speed test, and the compatibility check tells you what it means. More in our guide to upload speed.