Telldus NET DHCP client problems

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AndreasB
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Joined: Thu Jan 18, 2018 11:08 am

Telldus NET DHCP client problems

Post by AndreasB » Thu Jan 18, 2018 11:08 am

I tried to connect Tellstic Net (v4) in a few different configurations (via PC with Internet Connection Sharing, via PC Network Bridge, directly to router).
Since all except the last configuration didn't work, I have wireshark-monitored the DHCP communication with the Tellstick Net and have found a couple of problems which may cause it not to receive an IP adress (keeps the red light on).
This post is to give Telldus some information about the problem and to show people having problems (there are some posts in the Swedish forum) what could be the root cause.

The normal DHCP sequence is:
Client: DISCOVER (may contain a desired IP adress, normally the last one used)
Server: OFFER
Client: REQUEST
Server: ACK

Problem 1: The Tellstick sends its REQUEST, but exactly two seconds later, if it hasn't received any ACK, it sends a new DISCOVER and ignores the coming ACK. So if your DHCP server takes more than two seconds to respond, the Tellstick will never get any address. More than two seconds is not unusual, I think, because the server may ask on the network if there is any other node using that IP. My Win7 PC takes more than three seconds, for example, and I have heard others talk about five seconds. My conclusion is that the timeout is far too short.

Problem 2: The Tellstick includes a desired IP address in the DISCOVER message, which is fine. But if the server doesn't approove that address it may (according to wikipedia, and I may have seen the same thing in my router) silently drop the DISCOVER message and not respond. The client should then (again according to wikipedia) timeout and send a new DISCOVER without any desired IP adress. The Tellstick, however, keeps sending the same identical DISCOVER message over and over, possibly never getting any OFFER.

If there are other people with more DHCP knowledge out there, please add your comments.

Note that the red light is on also if the physical cable is not properly connected, so check that part first before you blame the DHCP. Unfortunately I don't know the best way to do that without using Wireshark, but you should see a difference if you look in ControlPanel/NetworkConnections in windows.

micke.prag
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Re: Telldus NET DHCP client problems

Post by micke.prag » Thu Jan 18, 2018 11:08 am

Thank you very much for this. Could you please report it to our bug tracker?
http://developer.telldus.com
Micke Prag
Software
Telldus Technologies

jtlaine2
Posts: 4
Joined: Thu Jan 18, 2018 11:08 am

Re: Telldus NET DHCP client problems

Post by jtlaine2 » Thu Jan 18, 2018 11:08 am

When will you fix this bug?

Br
Jouni

MaRaSu
Posts: 2
Joined: Sun Mar 04, 2018 7:37 am

Re: Telldus NET DHCP client problems

Post by MaRaSu » Sun Mar 04, 2018 7:50 am

I wonder if I'm having the same bug.

First installation with my ZNet lite v2 went fine (connected to my Apple Airport --> ip switch --> WAN router). I got all 433MHz and Z-wave devices activated etc. I had already previously used net v2 so Telldus Live! account was already ok to start with.

Then I wanted to check if I could get a better signal for ZNet lite v2 and moved it over to different room and connected to my wall socket which goes straight to my ip switch. Turned ZNet on and have not been able to make it connect ever since. It just keeps on flashing red on status led.

Can I reset it somehow to see if that fixes it? Any other workaround ideas?

etompau
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Location: Skåne

Re: Telldus NET DHCP client problems

Post by etompau » Sun Mar 04, 2018 8:14 am

MaRaSu wrote:
Sun Mar 04, 2018 7:50 am
I wonder if I'm having the same bug.

First installation with my ZNet lite v2 went fine (connected to my Apple Airport --> ip switch --> WAN router). I got all 433MHz and Z-wave devices activated etc. I had already previously used net v2 so Telldus Live! account was already ok to start with.

Then I wanted to check if I could get a better signal for ZNet lite v2 and moved it over to different room and connected to my wall socket which goes straight to my ip switch. Turned ZNet on and have not been able to make it connect ever since. It just keeps on flashing red on status led.

Can I reset it somehow to see if that fixes it? Any other workaround ideas?
Do you use two routers on the same network? Has the WAN router DHCP functions?
Connect a computer to the same socket in your "IP switch" as you have used for the Tellstick, and verify that you have internet connection.

MaRaSu
Posts: 2
Joined: Sun Mar 04, 2018 7:37 am

Re: Telldus NET DHCP client problems

Post by MaRaSu » Sun Mar 04, 2018 12:40 pm

Ouch. Now I'm truly embarrassed...I was so sure that I had used in the past devices on this specific wall socket AND my ip switch indicated active line when I plugged in ZNet. Still, something was apparently wrong with cabling and there was no ip connection on that socket. Had to get a cable from a nearby wifi station and now ZNet is happily online again!

Thx etompau! Never wrong to remind of the basics ;=)

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