Intro to CGN (Carrier Grade Nat), its effects and its deployment

shah95

ExceptionaL
Dec 26, 2017
105
0
11
Sahiwal
Assalam o Aleykum, this is my first thread here guys, and after searching much on the web and doing quite a bit of arguing with call centre representatives, I have felt the need to open a thread up here on pg forum.

First, I will tell you about this CGN thing, this is a technique used by isps when they want to go absolutely cheap.

So you guys would have noticed that when ever we restart our router/modem, our ip gets changed, that is because isps always try to go cheap and use dynamic ips instead of allocating a static ip..

Now, if you see your WAN ip address under the info tab of your router/modem device, it will display a certain ip address.. IF this address starts with 10.x or 192.x then you are in for a bumpy ride of cgn.

Now if you google 'whats my ip' you will see a certain address, IF that WAN ip address of your router is NOT same as which google displayed in search results, and it starts with 192.x or 10.x or any ip address that is used for assigning to internal ip (you can search on the web to see all ip addesses that are used as internal ips), then you have CGN enabled on your network.

Basically, when we use internet there are two things mainly involved, one is your local machine ip address (internal ip address, which is always 10.x or 192.x and its assigned by your router/modem device) and second is public ip address (external ip address also called WAN address, its assigned by your isp, and it should NOT be in the range of 192.x or 10.x unless your isp has deployed CGN). Now router/modem purpose is to mainly transfer data to and from the both addresses.

So, CGN purpose is mainly to cut costs and use a single public ip address for all users behind a cgn router which is deployed at isp level, hence a private ip address is assigned to a user's wan ip and only one public address is used for thousands of external wan ip addresses to connect them to internet. Imagine it like an extension cable, you can plug your tv directly in the wall socket, but you don't have any more spare sockets there and you need to connect your stereo speakers and pc and you want to go cheap instead of buying and fitting a new socket in the wall, then you will need to use an extension cable, connect all your devices with it and then plug it in the wall socket. Thats CGN.

Isn't that a good thing? Yes it is absolutely, but for the network provider and not for the consumer. CGN blocks all incoming ports permanently, while it does increase security and protect from attacks, but while doing so it causes huge issues for connecting and playing multiplayer games (specially which are based on p2p technology) and some applications like utorrent, while internet is still accessible for them but it causes much connection issues and lag, and due to ports permanently blocked at isp level one cannot do port forwarding either, even enabling dmz (demilitarised zone) won't work.

CGN causes increased pings and lags, sometimes degrades performance too, I was surprised how much connection issues I was facing when playing games (particularly GTA Online which is based on p2p) no matter which network I used, so after much research I got some insight on this, strangely every mobile network in Pakistan has CGN deployed (all 4 mobile networks which I tested), other than ptcl evo and ptcl broadband (which I didn't tested, although I know ptcl is offering static ip, so it shouldn't have CGN), so I would like users to test about this CGN on their routers/modems too by above mentioned procedure. And do tell me if someone is using a mobile network and there is no CGN for them or no connection issues/smooth experience of multiplayer, also do tell me about your network's performance in playing multiplayer games and your ping times and lags (if any). This CGN has become a big issue (for me atleast). Also a list of networks that deploy CGN (country wide or certain areas) would be extremely useful..

In the end, enjoy your gaming and lets hope the best for our country's advancement in technology !

Sent from my S7 Edge using Tapatalk
 
Last edited:

murtaza12

Global Moderator
Global Mod
Oct 27, 2011
10,745
124
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Now, if you see your WAN ip address under the info tab of your router/modem device, it will display a certain ip address.. IF this address starts with 10.x or 192.x then you are in for a bumpy ride of cgn.
Very few ISPs use 192.x in a CGN setup. You have a very limited range of IPs to use.

Common practice is to use 100.x for internal IPs assigned to end users.

CGN causes increased pings and lags, sometimes degrades performance too, I was surprised how much connection issues I was facing when playing games (particularly GTA Online which is based on p2p) no matter which network I used, so after much research I got some insight on this,
CGN doesn't cause lag or increased pings.

It will obviously lag and pings will spike if you use a mobile network, but that will happen regardless of whether they're using CGN or not.

strangely every mobile network in Pakistan has CGN deployed
It's not strange at all. AFAIK, the only ISP that doesn't use CGN is Ufone, and that's because it has a hilariously low amount of subscribers.
However, I last heard about this some time back, so they may have switched to CGN now.

Jazz serves 56 million customers, out of those 56, almost 14 million are mobile data users (3G).

Imagine giving every single subscriber a public IP? It doesn't make sense to do so.

Mobile users don't need public IPs.

CGN is used by mobile networks across the world to cut costs.
 

shah95

ExceptionaL
Dec 26, 2017
105
0
11
Sahiwal
Very few ISPs use 192.x in a CGN setup. You have a very limited range of IPs to use.

Common practice is to use 100.x for internal IPs assigned to end users.


CGN doesn't cause lag or increased pings.

It will obviously lag and pings will spike if you use a mobile network, but that will happen regardless of whether they're using CGN or not.


It's not strange at all. AFAIK, the only ISP that doesn't use CGN is Ufone, and that's because it has a hilariously low amount of subscribers.
However, I last heard about this some time back, so they may have switched to CGN now.

Jazz serves 56 million customers, out of those 56, almost 14 million are mobile data users (3G).

Imagine giving every single subscriber a public IP? It doesn't make sense to do so.

Mobile users don't need public IPs.

CGN is used by mobile networks across the world to cut costs.
Yes, 100x is used but still all the ips I got were either 192.x or 10.x, 174.x is also a private ip address and is used for this purpose, but for CGN only private ip addresses can be used.

Now ufone is using this too, I agree that mobile users don't need public ips, but if they are advertising super high speeds and selling modems of which newer devices even have antenna slots and ethernet port (which surely people will use with PCs for playing games) then they should disable this cgn for those users or atleast give them an option to choose (with some premium charge). This horrendous policy of terrible quality of service and false advertising should be stopped.

Sent from my S7 Edge using Tapatalk
 

murtaza12

Global Moderator
Global Mod
Oct 27, 2011
10,745
124
69
Yes, 100x is used but still all the ips I got were either 192.x or 10.x, 174.x is also a private ip address and is used for this purpose, but for CGN only private ip addresses can be used.

Now ufone is using this too, I agree that mobile users don't need public ips, but if they are advertising super high speeds and selling modems of which newer devices even have antenna slots and ethernet port (which surely people will use with PCs for playing games) then they should disable this cgn for those users or atleast give them an option to choose (with some premium charge). This horrendous policy of terrible quality and service and false advertising should be stopped.

Sent from my S7 Edge using Tapatalk
The devices with ethernet ports are usually used at small offices, or homes where fixed line internet isn't available.

With that being said, I have never seen anyone at a home actually using one of those devices to be honest. The only places I have seen it are at a local Cash and Carry where the cash counters had a Zong 4G device connected to a LAN switch, and the other place was at the NADRA office where the two staff members at the ticket counter were using it.

Besides, not everyone is a gamer, so for them a modem like that with external antenna ports and ethernet ports is still quite useful. It's not being advertised for gaming anyway, and it never has.

CGN has minimal effects on other aspects of using the internet. Only P2P applications are disturbed by it, but everything else functions normally.
 

shah95

ExceptionaL
Dec 26, 2017
105
0
11
Sahiwal
The devices with ethernet ports are usually used at small offices, or homes where fixed line internet isn't available.

With that being said, I have never seen anyone at a home actually using one of those devices to be honest. The only places I have seen it are at a local Cash and Carry where the cash counters had a Zong 4G device connected to a LAN switch, and the other place was at the NADRA office where the two staff members at the ticket counter were using it.

Besides, not everyone is a gamer, so for them a modem like that with external antenna ports and ethernet ports is still quite useful. It's not being advertised for gaming anyway, and it never has.

CGN has minimal effects on other aspects of using the internet. Only P2P applications are disturbed by it, but everything else functions normally.
Agreed totally. Although I see a rapid rise in mobile broadband, and all my friends and acquaintances have got one of these devices (many use them for gaming too), although wired dsl is still there, but its death is inevitable, and it would be the era of fiber optics and mobile broadband from now on, point is mobile broadband is not that much scarce either, and since 4.5G is also been advertised, that would mean more increase in mobile broadband usage, athough that 4.5G is a dud in reality.

But I would love if i had the option to choose, maybe a static ip without any cgn or such for Rs 500+ , would be worth it. But as I see every 4G network losing its speed each day, I fear people would need to stay up all night (to be able to use 4G speed) [emoji23]





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murtaza12

Global Moderator
Global Mod
Oct 27, 2011
10,745
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69
Agreed totally. Although I see a rapid rise in mobile broadband, and all my friends and acquaintances have got one of these devices, although wired dsl is still there, but its death is inevitable, and it would be the era of fiber optics and mobile broadband from now on, point is mobile broadband is not that much scarce either, and since 4.5G is also been advertised, that would mean more increase in mobile broadband usage, athough that 4.5G is a dud in reality.

But I would love if i had the option to choose, maybe a static ip without any cgn or such for Rs 500+ , would be worth it. But as I see every 4G network losing its speed each day, I fear people would need to stay up all night (to be able to use 4G speed) [emoji23]

Sent from my S7 Edge using Tapatalk
Yeah too bad advancements in technology here are a few years behind the rest of the world.

Good post though.
Will be informative for those who are new customers of StormFiber, TES and Nayatel.
 

GenFaz

Intermediate
May 20, 2016
135
2
13
Islamabad
Hello!

CGNAT is indeed a cost saving measure as scarcity of IPv4 blocks has resulted in costs skyrocketing ... as most ISPs are not sure about moving to IPv6 ... mistaken belief about NAT providing security ... it has been discussed here before in the forums ... a way of "escaping" CGNAT is to tunnel your way out of it ... VPS (allows you full control) services are quite affordable if this is the sole purpose especially ones around Eastern Europe ... see https://lowendbox.com and https://www.digitalocean.com/community/tags/vpn?type=tutorials ... there are also ssh tunnels ... softether and zerotier can also help!

Hope this helps!

Regards,
Ahmed
 

blackclouds

Intermediate
Feb 2, 2011
193
0
21
Im on Optix and my IP dsnt change everytime i restart my modem. Is it a good thing or bad? I would rather like it to change though.
 

shaheerk

Well-known member
Feb 5, 2013
2,359
100
68
Im on Optix and my IP dsnt change everytime i restart my modem. Is it a good thing or bad? I would rather like it to change though.
It can sometimes change after a few days.

Sometimes.

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shah95

ExceptionaL
Dec 26, 2017
105
0
11
Sahiwal
Hello!

CGNAT is indeed a cost saving measure as scarcity of IPv4 blocks has resulted in costs skyrocketing ... as most ISPs are not sure about moving to IPv6 ... mistaken belief about NAT providing security ... it has been discussed here before in the forums ... a way of "escaping" CGNAT is to tunnel your way out of it ... VPS (allows you full control) services are quite affordable if this is the sole purpose especially ones around Eastern Europe ... see https://lowendbox.com and https://www.digitalocean.com/community/tags/vpn?type=tutorials ... there are also ssh tunnels ... softether and zerotier can also help!

Hope this helps!

Regards,
Ahmed
Yes , you can buy a vps or dedicated server , you can even use it to host websites too , but the hassle of buying a server and then simply setting it up is not worth for the average user I think, they would be better of getting a static ip from a wired internet provider. But your post was much helpful for advanced users who know about linux and have knowledge about networking.

Btw, we need to buy a vps or dedicated server for this to work.

Sent from my S7 Edge using Tapatalk
 
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