WAN Failover for VoIP

[kordm]

We're transitioning our main office to a new VoIP solution (feel free to welcome us to the 21st century) and we have a bit of an issue with our failover link.

We have a backup DSL link but it's really only capable of about 5 Mb/s (we're somewhat rural) and can't handle the WAN traffic of ~300 clients. Is it possible to configure traffic shaping in a way that allows only the Voice VLAN to access the WAN 2 and cellular uplinks when the primary link goes down?

EDIT: Our gateway is a Meraki MX84. I understand we'd need a more esoteric SD-WAN solution to allow seamless failover without dropped calls, I haven't really explored that option yet.

[NolanHerring · Accepted solution]

There is a way

Contact support, and ask them to make the cellular firewall rules under the firewall settings 'act as firewall rules for WAN2'.

Then under the cellular firewall rules, only allow the voice vlan, and then block everything else. That will basically only allow voice to go out cellular/wan2.

Why the firewall rules don't have a separate section for WAN2 firewall rules is beyond me, hopefully they'll release that one day.

[BC1122]

Hi Nolan, Are you able to verify "make the cellular firewall rules under the firewall settings 'act as firewall rules for WAN2'."? 

We contacted the Meraki support, the engineer tells us this cannot be done. I was wondering if this is just a guess or this is really achievable. 

[NolanHerring]

It can done, and I rely on that hidden feature all the time. The tech your dealing with might not be aware of it, so you might want to ask that he escalate it. Or open another case and get another tech.

[BC1122]

We contacted the Meraki support, the engineer tells us this cannot be done. I am wondering if this is just a guess or this is really achievable.