SBC with Dynamic IP Address

[TitleRequired]

I appreciate an SBC works best on a static IP, but in some situations we have devices where we do not control the infrastructure and for whatever reason a static ip or reservation is not available.

It leads me to wonder why in the properties of an extension you cannot select an SBC by dropdown, rather than having to manually input an IP address.

When an SBC registers to the 3CX server it refreshes its local IP address, but this setting is not populated throughout the rest of the system, leading to additional work required to update Hotdesk or Dect phones, or any extension configured to use that particular SBC. Painful!

If it is possible to do it another way happy to be educated! Or if implementing this is not possible, the reasons why?

 

[NickD_3CX]

Hi there!

Assuming that the SBC IP Changes and the IP Phone that is already configured to look at its old IP loses its registration.
At this point, the PBX does not know how to reach the IP Phone, so how is it going to notify the IP Phone that it should go and re-download its new settings?

This should answer both why a Static IP is important and other complications to your idea/suggestion about having the a SBC drop-down instead of filling it in manually.

 

[TitleRequired]

That is true yes, however, lets assume you reboot a phone in that scenario, it goes to its provisioning URL to download it's config file, which still points to the old IP of the SBC. So it downloads its config as it still has internet access, but it cannot talk to the SBC or register on 3cx afterwards.

If 3CX updated the configuration of SBC X, with its new IP, when the phone went to the provisioning URL to download its settings it would get the SBCs new IP. So, it would still have lost its connection when the IP of the SBC changed but as soon as the SBC came back online a reboot of the phone would resolve that.

 

[cobaltit]

Well I think the thinking is the phone won't be able to communicate with the SBC but it will be able to communicate with the PBX as the provisioning path hasn't changed. As such, if 3CX updated the config with the new local IP then the next time the phone re-provisions it will be know the new SBC IP.

 

[cobaltit]

Looks like we both posted at the same time. Anyways, as a work around, you can use a DNS name for the SBC.

 

[TitleRequired]

Yeah - i thought about a DNS name, but i can see two possible problems with that.
1.In some environments phones are going to be using public DNS Servers, so wont be able to resolve internal names.
2. You are still going to have to make sure the IP and the name keep in sync, and if you are not managing the IP you wont necessarily know when it changes, to know to update the record.

Its definitely a niche issue, and probably not worth their development time when i expect 99% of SBCs out there are on static or reserved IPs.

 

[cobaltit]

1. Not a problem, I wasn't talking about using internal DNS.
2. Yep. Many DNS providers have APIs for updating records. You make a script to check and update the record if/when the IP changes.

Think of it like a dynamic dns client but using the private IP instead of the public IP.

 

[TitleRequired]

Yes i suppose that is one way to go, but it's less work for me if 3CX just implement this change for me ;o)

 

[NickD_3CX]

That is true yes, however, lets assume you reboot a phone in that scenario, it goes to its provisioning URL to download it's config file, which still points to the old IP of the SBC. So it downloads its config as it still has internet access, but it cannot talk to the SBC or register on 3cx afterwards.

If 3CX updated the configuration of SBC X, with its new IP, when the phone went to the provisioning URL to download its settings it would get the SBCs new IP. So, it would still have lost its connection when the IP of the SBC changed but as soon as the SBC came back online a reboot of the phone would resolve that.

I suppose that is true yes, although it would require a manual action from the User.

I can't remember having seen this in the 'Ideas' section, but if you feel this would greatly improve the usability, then maybe you should consider creating it there.

To be clear, this will never replace the recommendation for a Static IP, because users will still find themselves with a non-working phone if the SBC IP changes.
The only thing it would improve is the temporary solution, and I say temporary because the actual solution would be to set it to a Static LAN IP.

 

[TitleRequired]

I did have a look but it said, YOU HAVE INSUFFICIENT PRIVILEGES TO POST THREADS HERE so i posted here instead.

 

[NickD_3CX]

That is correct, to post in the 'Ideas' section you need to be Gold or above as a Partner status.
Someone else viewing this could do it.

 

[TitleRequired]

A static IP does solve the problem, agreed, but you still have to manually enter the IP on every extension you add so it would be good to improve that bit at least.

 

[Lilian449]

How will you know what Remote IP the SBC gets assigned to use in provisioning ahead of time? And/or guarantee that the device doesn't change IPs in the event of a power outage? I'm not sure I understand the benefit of a dynamic address in this scenario.

 

[TitleRequired]

I don't think there is a benefit to using a Dynamic IP address, I'm saying sometimes it cannot be avoided.
In fact you are correct, a power outage caused this particular SBC to change it's IP Address which prompted this thread.
As the SBC registers it's IP address when it logs in to 3CX, we do not need to know what it is, if the provisioning file is dynamically update to point to whatever the current IP Address is.

To be clear I am not advocating the use of dynamic IP's with SBCs. I do think that having to manually type the IP address in to each extension is a bit of a pain, and could be streamlined with a dropdown menu.