why the external ips are different in router and other sites of tests

rajujayaraman

rajujayaraman

Newbie
Messages
336
Location
NA
ISP
bsnl
Hi, i have noticed this weird behaviour of showing two different ips , external ips on router and other sites .
Till yesterday, on checking both , the external ip given in router would tally with the test sites like speed net etc. but to day, i found the external ip router as different from router. The router shows , the ip, starts with 100,x,x,x which is not usual in bsnl. The ip would start from the correct bsnl owned ips with the gateway showing start with the same first octet.
But to day, i noticed that the reserved ips from iana start with 100 being shown in the router, where as the test sites different one actually belongs to the ISP, ie, bsnl
Do anybody noticed this
i tried reseting the router and after logging in also i found the router ip , showing as iana reserved , gateway shows as that of the BSNL
please experts and admin
 
Oh no, 100.64.0.0/10 IP series is reserved for carrier grade NAT 😔😔 Could you please post the exact IP address?

Did you make any plan changes or enable VOIP or anything?
 
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@rajujayaraman are you on FTTH or ADSL? maybe BSNL is now slowly going to migrate to CG-NAT due to IPv4 address shortages.

So far my FTTH connection is still single public facing IP.
 
Hi if that is the case,how it shows correct ip on websites such as shields up speed test net. What else I could try
 
It's something done on their backend @rajujayaraman, it's basically a different configuration done on their side to reduce IPv4 usage as @vishalrao pointed out. You can read more online, look for CG-NAT (carrier grade NAT)

You can't do anything on your side to work around it unless you opt for a static IP address perhaps (which is chargeable).
 

BSNL is using NAT system.

100.xx ip in your router is ip of bsnl server/router which will perform NAT (Network Address Translation). This ip can be routed outside of bsnl network.

Ex- if you connect your mobile to your wifi in settings you will see ip allocated to your mobile by your router like 192.x.x but in speedtest you will see your public ip.
 
Hi, i know something on what you say. But bsnl broadband users, please let me know, it is also yours. Normally IANA reserved addresses are not given as external ips day before yesterday. I also noted that , bsnl server starting 218.x.x.x is given as gateway in router.
i have checked and found that ipv6 is also enabled in my network configuration on the adaptor settings.
i tried system restore to rule out any injection.
No information of this change, if at all, by the service provider generally in news paper etc.
I am not able to give exact ips, but could say, that the router ip address starts with 100 andserver starts with 218 in router, and public ip of bsnl is shown in other sites starts with 117
 
Hi, vishal rao, noted your point. It is adsl modem not fth.
Will it show differently the public ip of one connection?
Could you please give link about cg nat and how bsnl is going to implement
Why not bsnl switch to ipv6, knowing well that ipv4 address is scarce.
I think that all other ISPs upgraded to ipv6. Is there any resource crunch for switching to ipv6
 
Hi, is there a way to find , if ouir ISP is using cgn
Do you mean to say, that in those cases where cgn is used , you get two external ips. please
 
No, you get a WAN side IP address from non publicly routable IP address ranges (100.64.0.0/10 is designated for large scale NAT done by ISPs called CG-NAT, the ISP doesn't have to necessarily use this IP pool, and can use 10.x.x.x ranges as well, like few other ISPs) which would obviously be different from your true externally visible IP address.

This is exactly what is happening in your case.
 
Hi, varkey, do you mean to say that bsnl is now using cg-nat to get me the ip allotment. Is there any way, to check if our bsnl started using cg.nat, which they hitherto have not touched.
I used to get the same ips both in router and on sites.
, normalThat would also be , same first octet in the gateway. Normally i have 117,36,45 etc.But the ips that is given in router tallied with the router.
Is there any check to see if bsnl uses cg nat or is it some kind of a third parties .
 

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