LTE NB-IoT DNS

[Redferne]

@aris Actually in our case the DNS problem was caused by Sequans using EPCO in their NB-IOT firmware. Once we added support for EPCO in our network we got the DNS server info populated.

[combaindeft]

Hi all,

From what I've read, heard and seen ... NB-IOT isn't ment to have DNS ...

LTE-M (or LTE-CATM1) networks ... contrary to NB-IOT ( or LTE-NB1) networks .... do support DNS ...

As someone so elegantly put it ... Think of LTE-NB1 as the lowest power consumption .vs LTE-M vs LTE ... they had to the "optimise" LTE-NB1 network as much as they could for longterm lifecycle in the field... and removing DNS lookups is a feature they had to remove ... as the devices conceived to LTE-NB1 is "wake-up, AS-FAST-AS-POSSIBLE-get-the-data-out, turn off Modem, and put device to deep sleep" ...

With that in mind, all in all, it makes 100% sense not to have DNS in LTE-NB1 ... and all we have to do is design our solutions around this factor.

[Lonefish]

@combaindeft I can't seem to find anything that supports this claim (or denies it).. Where have you heard/read/seen this?

Not stating you're wrong, it doesn't work with my fipy either, but looking for an answer why not and what would be a solution/recommended way of communicating then.

[Paul Thornton]

@lonefish @combaindeft took a quick google myself and couldnt manage to find anything on this either. If you have any documentation or links to share Id love to read them.

[combaindeft]

@paul-thornton @Lonefish

I'm in talks with our operator, Telia here in Sweden ... regarding why they didn't implemented the network for NB-IOT (LTE CATNB1) ... with DNS support.

But I got it confirmed today from our contact person:

"There is no restriction in 3GPP as regards to the support of DNS in LTE-CATNB1"

[so I updated my previous post to reflect that...]

But, for some reason, it seems that operators around the world are ALL implementing their LTE-CATNB1 networks without DNS supports.

Talking with our backends guys ... they said to think of LTE-CATNB1 as a "LoRa Network" as it's competing against it. Meaning a device should only wake-up, quickly burst the data over, and enter deep_sleep ... Hence removing DNS, and implementing an only IP network. Make it more efficient, as there is no dependency on a Download-link to get DNS working

Furthermore, signs of this is that our operator only supports UDP-packets! ... meaning we are only sending data ... and hoping it'll reach the server (like in a LoRa-network ...)

[combaindeft]

@Paul-Thornton @Lonefish

Hi again,

Got a reply from our contact @Telia ... and the the devices they use, do support DNS-lookups ... natively ... from the Device manufacturer.

They can enter any http://www.address.com and it works.

So I guess then, it's more up to PyCam @Paul-Thornton to implement a native DNS-Client into the MicroPython Firmware.

I'm guessing adding a list of "prefered" DNS-Server is the way to go ... like adding Google's own DNS-servers (8.8.8.8) to the list ... etc etc ... and then having a built-in-DNS-Client that does the DNS-Lookups via UDP ... as the LTE-CATNB1 network(s) are most likely UDP based ... at least it's for us here in Sweden with Telia ...

Further more, DNS is TCP / UDP agnostic ... and protocol independent ...

So, yeah, guess it's 100% in the hands of PyCom to implement their own native DNS-client into the Firmware :-) @Paul-Thornton @Lonefish

[Lonefish]

@combaindeft That was my plan too, to be honest, do the dns-request myself. When I checked the modems DNS with AT-commands it did show an empty DNS-address. But, remembering cisco and OSI-layer, DNS is an application protocol, so it's not necessarily an implementation problem in the standard as you said.

[combaindeft]

@lonefish

I've been doing some google searching (https://www.google.se/search?num=100&q=%2Bmicropython+dns+client) and looking up some Python-based DNS Clients:

• https://github.com/lettier/dnsclient
• https://github.com/ValeryTyumen/DNS-Client
• https://github.com/shubhammatta/DNS-Client-Socket/blob/master/DNS-Proxy-Server.py
• http://www.dnspython.org/

and see which one is the easiest to port to MicroPython

@Lonefish ... may we should start a GitHUB project for "our" MicroPython DNS-Client port for PyCom devices?

[combaindeft]

@Lonefish @Redferne

Take a look at the new 1.18.2 release ... they implemented so we can add our own dnsserver ...

Tested it now, and it works 👍🏻 ... we got DNS over NB-IOT 👍🏻

Please update to the latest 1.18.2 (stable):
https://forum.pycom.io/topic/4361/new-stable-firmware-release-v1-18-2

or to the latest 1.20.0.rc7 (development):
https://forum.pycom.io/topic/4359/new-v1-20-0-release-candidate-v1-20-0-rc7

Use the following to set your DNS Server to Google's DNS Servers ...

usocket.dnsserver(0,'8.8.8.8')
usocket.dnsserver(1,'4.4.4.4')
usocket.dnsserver()
('8.8.8.8', '4.4.4.4')

Then bring up your LTE Connection, and do:

>>> print(usocket.getaddrinfo("www.google.com", 80)[0][-1])
('216.58.211.4', 80)

[Lonefish]

@combaindeft I finally found the time to test this and it works indeed! Just a heads up, Google DNS is 8.8.8.8 and 8.8.4.4, not 4.4.4.4 :)