Multi (3) NIC question

[my3cxRC]

We currently designed our system so that the 3CX server would have 3 NICs to segregate traffic for data/Internet, SIP provider and the phones. Most of the multi NIC posts here consist only of 2 subnets where they combine the phones and the SIP provider. In our case, the SIP provider supplies a router through which only voice traffic passes (like the SingTel set up). The reason for our 3rd NIC is to totally isolate phones into their own VLAN with no default gateway provided to the phones. I was just wondering whether that would work or not? Reading from the supported network configuration document, it seems that the phones would still need to have a default gateway assigned?

Is my understanding correct and there is no use to keep the phones on a separate VLAN?

For those wondering why we're doing it this way:

1. We want data-only traffic to flow from anywhere to the 3CX's NIC1 which has an IP address that is mapped/NAT'ed to the public IP
2. We don't want our VoIP provider getting access to any of our other network via their on-prem provided router (i.e. they can only see the 3CX's NIC2 and the server itself has no routing services enabled)
3. We want to isolate our phones so that they are accessible only via 3CX's NIC3 and again this is also non-routable

Are we over killing it and should we just stick to 2 NICs?

 

[eddv123]

In my opinion (and based on client size) I think it best to stick to 2 as per the guidelines for Multiple internet gateways and keep things as simple as possible (and supported): https://www.3cx.com/blog/docs/network-configurations-supported-3cx-phone-system/

I have done this setup for Singtel in Singapore and TATA in India and your solution would require an extra layer of static routes on the server at the very least - in the case of the data traffic however (if you were to use split VLAN's of course) are you using deskphones, clients or a mix of both (CTI) ?

 

[cobaltit]

Typically I would just do a two NIC setup with the provider handoff and phones in the same subnet. There's no reason a 3 NIC setup shouldn't work as long as you follow the same principles as the 2 NIC setup but I haven't done it.

 

[my3cxRC]

In my opinion (and based on client size) I think it best to stick to 2 as per the guidelines for Multiple internet gateways and keep things as simple as possible (and supported): https://www.3cx.com/blog/docs/network-configurations-supported-3cx-phone-system/

I have done this setup for Singtel in Singapore and TATA in India and your solution would require an extra layer of static routes on the server at the very least - in the case of the data traffic however (if you were to use split VLAN's of course) are you using deskphones, clients or a mix of both (CTI) ?

Hi Edd,

We're going to be using a mix of deskphones and CTI. Currently, we have been able to get it to work on deskphones.

 

[eddv123]

We're going to be using a mix of deskphones and CTI. Currently, we have been able to get it to work on deskphones.

The only reason for the mention is due to the use of (if you are) different VLAN's. Since the phones will reside in the Voice VLAN and CTI to clients in the data, intra-VLAN routing should be in place to facilitate this.