MX WAN Subinterface

[Hussam]

Hello All,

We have MX with more than 4 ISP link
and we just have 2 WAN interface
Can we use subinterface on the MX??

[ww · Accepted solution]

you can't

[MerakiDave]

No, the MX does not support subinterfaces today.  Depending on your design, there could be a simple method to provide a workaround, but you are still limited to 2 WAN interfaces plus a tertiary cellular backup perhaps.  The workaround I mention is if you are leveraging 2 subinterfaces on a physical port today, then you simply have a dot1q trunk interface come into a switch or the MX itself, and then configure 2 access ports with the appropriate VLAN IDs (to simulate the 2 subinterfaces) and connect patch cables from those 2 LAN ports into WAN1 and WAN2.  That can work around the subinterface requirement, but again, you are limited to two WAN interfaces.  If you need to leverage SD-WAN functionality with 4 ISP links, today you might consider a Cisco Viptela solution.

[PhilipDAth]

When I hear people are using more than a couple of ISPs I ask why?

Typically if you take that some money and invest it in just two ISPs you can get a much better service.

Sometimes they are doing it for historic reasons that no longer apply.

[Nick]

There can be many reasons though Philip

Building issues, you are unable to get another line in or a leased line.

Capacity at the local exchange, only ADSL is available

Different services or contracts, i.e a dedicated breakout VOIP service with one data and a backup data line would put you over the limit

[Nick]

Its worth noting we have hit the 2WAN limit quite regularly on our installs. Its quite common for mid size businesses to have 3 WAN's if they are using a short haul VOIP connection and have two Data connections. A 3 WAN ability would be very useful