CGNAT?

What are the common limitations when you are being CGNATed by your ISP. I realise incoming connections are not possible. In this day and age it could be considered an advantage. No more being continuously scanned for open ports.

Brsk's network is live 100 yards from me. My area is 'coming soon'. If I were to take their 900/900Mb service, by the time I came out of the 9 month half price period, the full price would be less than what I am paying for 125Mb from virgin media. They charge extra to provide a fixed IP address otherwise it is CGNAT.

The other limitations are the ones that come along with sharing an IP address with other users.

The main one being that a website/service that you are using can decide that they behaviour they are seeing from you IP address is unusual/problematic in some way. This can result in you seeing more website "prove you are a human" quizzes.

Exactly how much of an issue this is depends on things like how well your ISP implements CGNAT, what their standing is in the industry (how trusted are they), who you are currently sharing an IP address with, etc

I'm on Starlink, with CGNAT. I don't tend to see many "are you human" challenges. When I was running my home Internet on EE, their CGNAT tended to trigger a fair few more challenges than I see on Starlink.

To be clear though, not all "are you human" challenges are down to sharing an IP address.

There is another issue that I've run into on some CGNAT setups. If they are setup so that you IP address can change regularly (multiple times a day) or so that your traffic comes from multiple IP address, this can cause problems. For example it used to be hard to login to Santander on CGNATs that sent your traffic from multiple IP address, I've had to use a VPN in the past to work around this, thankfully Santander fixed the issue at their end.

With Starlink you are on the same shared IP for days/weeks and your traffic is only ever sent from that one address.

Anything that relies on setting up direct connections is going to fail to work properly, the biggest sign of this is going to be playing online games where there's not a dedicated server. Most modern services can work around CGNAT now, so you shouldn't have issues in Teams, Zoom etc. You'll possibly never get a VoIP phone to work that uses SIP unless it's via a setup provided by your ISP.

If Brsk offer IPv6 as well then CGNAT isn't really an issue as long as the services you're using are modern enough. I have a low opinion of ISPs doing CGNAT without IPv6.

I currently use VOIP though a Grandstream HT812. I believe this can be configured to use only ipV6. I currently use a tunnel broker for ipV6 connectivity so could test reconfiguring it. Brsk appear to support ipV6.

"IPv6: Brsk fully supports IPv6, and every customer has access to their own public IPv6 prefixes. This will allow you to access your devices remotely, but only from other networks that also support IPv6. "

VoIP will work fine then as long as your provider supports IPv6 as well, which unfortunately seems to be rare.

On the skin of it, I would say harder to run servers, some cases impossible, multiplayer gaming harder, and more likelihood of been affected by IP based bans when a number of people are actively sharing the IP address.

In reply to a post by Chrysalis:

On the skin of it, I would say harder to run servers, some cases impossible, multiplayer gaming harder, and more likelihood of been affected by IP based bans when a number of people are actively sharing the IP address.

Unless they can all use IPv6, which means nobody on Virgin Media or Plusnet currently.

Sadly there is no other solution as there are no new IPv4 blocks available, and it is amazing that two large UK ISPs have not yet enabled v6.

Edited by jchamier (Tue 10-Jan-23 18:05:47)

SIP (AAISP's service) works fine via Starlink's CGNAT, I didn't have to do anything special to make it work.

In reply to a post by jchamier:

In reply to a post by Chrysalis:

On the skin of it, I would say harder to run servers, some cases impossible, multiplayer gaming harder, and more likelihood of been affected by IP based bans when a number of people are actively sharing the IP address.

Unless they can all use IPv6, which means nobody on Virgin Media or Plusnet currently.

Or Talktalk. Or Vodafone.

In reply to a post by jchamier:

Sadly there is no other solution as there are no new IPv4 blocks available, and it is amazing that two large UK ISPs have not yet enabled v6.

Unfortunately, deploying IPv6 in access networks does nothing by itself to help with the shortage of IPv4, since users still need to be able to access IPv4 content - which is most of the Internet.

Even though conceptually it would be straightforward for the big content providers to enable dual-stack for IPv6 access, most of them haven't - including organisations like the BBC, which historically have a reputation for technical clue.

Why not? I guess because they're worried that their systems for tracking, advertising and monetising users might not be compatible.

In reply to a post by candlerb:

Even though conceptually it would be straightforward for the big content providers to enable dual-stack for IPv6 access, most of them haven't - including organisations like the BBC, which historically have a reputation for technical clue.

EE mobile manages to provide v6 to end users and route data for v4 through the v6 network, I assume using CGNAT techniques, but there were some NANOG slides circulating the net 5 or so years ago.

Why not? I guess because they're worried that their systems for tracking, advertising and monetising users might not be compatible.

For BBC I assume they are worried about regional controls, but everyone yes, agreed.