Solved Factory reset of Snom D717 does not send multicast packet

[Stulander]

Hi,

I have read the following article: https://www.3cx.com/docs/plug-and-play-ip-phone/

I deleted a bunch of phones from 3CX (little X button on the far right):

I factory reset the phones (power off, hold #, power on, option 1) as per: https://www.3cx.com/sip-phones/factory-reset-snom/

I ran wireshark on the same subnet as the phones and 3CX (192.168.2.0/24) I do not see multicast packets coming from the phones IP address. When I first turned on the phones, they showed up in the 3CX console. Is there any other way to force them to send out a multicast message?

3cx server netstat:

Of course switches all support multicast as they showed up the first time.

Please don't tell me I have to enter the mac addresses of 30 phones manually!

Thanks

 

[cobaltit]

So I guess the first question is why did you delete the phones from the phones tab instead of provisioning? Was there an issue preceding this issue?

Second question is did you read the guide on using those phones?

https://www.3cx.com/sip-phones/snom-710-720-760/#h.7ls0w5vyhlnd

Because the firmware in your picture is not current and Step 1 is to upgrade the phones to the current firmware. You could be dealing with a quirk in the firmware on those phones.

 

[AWS2P]

latest firmware is

DL link
https://downloads.3cx.com/downloads...areupdates/snom/snomD717-10.1.54.16-SIP-r.bin

 

[Stulander]

So I guess the first question is why did you delete the phones from the phones tab instead of provisioning? Was there an issue preceding this issue?


Second question is did you read the guide on using those phones?

https://www.3cx.com/sip-phones/snom-710-720-760/#h.7ls0w5vyhlnd

Ah that picture is confusing. Sorry. Those were just two phones of 30 that I had not updated. They have since been updated to the latest firmware and deleted from the console.

I've updated all the phones to the latest firmware. They were not showing as having been updated to the latest firmware so I thought "I'll delete them, and reboot them, then they will show up with the latest firmware." This was obviously a stupid thing to do but it has now been done. I thought I was just doing something trivial so it wouldn't matter if I deleted them. I'd googled a fair bit before it and was under the impression they'd either show up after a reboot or a factory reset.

Yes, I have read the documentation on the phones.

1. Does 3CX keep a record of phones that it has detected?
2. Is this expected behaviour?

I'll run a tcpdump on the 3CX server itself to see if I can see the multicast messages, just occured to me they might be getting dropped before wireshark sees them?

 

[JohnS_3CX]

Hi,

Start a capture on your PBX, and then factory reset the phone.
Once it has reached its initial screen (Language Selection) you can now stop the capture and open it in Wireshark. Use this filter to see if your PBX received the multicast message:
ip.dst==224.0.1.75

Do you see anything like this?


https://www.3cx.com/docs/capture-network-traffic/

 

[Stulander]

Hi,

Nope.

I ran the capture using the built-in method through the web console as per the link you provided.

I then ran the following command on the 3CX server, just as an additional check

tcpdump -i ens32 -s0 -vv net 224.0.0.0/4 -w /tmp/capture1

The filter you provided gives no result. I made sure to run both captures, then factory reset the phone, and then stopped the capture after it got to the language selection screen.

ip.addr >= 224.0.0.0 as a filter shows lots of multicast traffic but nothing from the phone. I've also tried reflashing a phone with Snom firmware then reflashing again with the 3CX firmware, no luck.

It's like the phone just won't do multicast anymore. Really weird. I'll maybe try a port mirror on the switch the phones are connected to and run a capture on a laptop connected directly to the same switch. Maybe the multicast traffic is getting dropped somewhere before it reaches the 3CX server - not sure why though as it worked the first time.

 

[Stulander]

OK, it was the switch the phones are connected to. For some reason disabling STP has resolved the issue. I have no idea why, apparently I don't understand it well enough. I must have screwed up the implementation somehow.

 

[JohnS_3CX]

I was going to suggest port mirroring next but no worries, glad you found it!