MX68 - 84 QoS

[znaqvi786]

My customer is moving to WebEx calling from thier On-Premises call manager and some of the branches has Meraki MX, the question is if MX68/84 can do QoS for voice leveraging broadband and if there is any specific software version required on them.

[GIdenJoe]

All MX appliances have traffic shaping capabilities.
If you are fully tunneling to a DC MX then you can have two way QoS but if your transport for your voice call manager is the internet then you will only get outbound QoS.

On the security & SD-WAN -> traffic shaping page you can set these options.

Step1: Make sure your upstream and downstream bandwidth is set to the correct maximum values as your circuit speeds.

Step2: Make sure you match your voice traffic either through L7 application matching or through L3/4 IPs and ports.  And give it a DSCP value of EF(expedite forwarding).  You can set the queue to high but it should take the real-time queue by setting your DSCP value to EF.

Step3: Match some other traffic types and give them high/medium/low queuing service.

The logic is as follows.
- Each WAN interface on an MX has 4 queues
- The realtime queue is a strict priority queue (the moment 1 packet is waiting in that queue it gets serviced first)
- The other 3 queues are weighted bandwidth queues where high gets 4/7 of the maximum bandwidth, medium gets 2/7 and low gets 1/7.

So imagine you have a circuit with 70 Mbps upstream:
High would get 40 Mbps, medium 20 Mbps, low 10 Mbps.  However if one packet enters the realtime queues the other queues stops servicing and the realtime queue is emptied first.

[ww]

For 18.2  

• Firmware 18.2 and above: Class Based Weighted Fair Queueing with Deficit Round Robin is enforced on token bucket allocations. Allocation ratios are as follows:

  • Realtime: 8

  • High: 4

  • Medium: 2

  • Low: 1

[iores]

@ww Which traffic and how it gets in the realtime class? Is this something Meraki does automatically or you need to have a matching rule which will assign EF value? 

[ww]

Your traffic needs to arrive with dscp 46/ef on the mx. So tagging should be done at client, wifi or switch.

Or using the default traffic shaping rule "should" work for voice traffic. (But meraki documentation really lacks info on what the default shaping rules do and which traffic it matches)

[znaqvi786]

Thanks, Any specific software version required for this?

[CptnCrnch]

Nope 😎

[GIdenJoe]

Nope, as I already outlined.  In dashboard go to your network where you have the MX and in the menu select Security & SD-WAN -> Traffic Shaping.

All settings are available on that one page.

[EmilyLangford]

MX68 and MX84 can do QoS for voice over broadband.

You use Traffic Shaping in the Meraki dashboard. Set your WAN speeds first. Then create rules to prioritize WebEx calling, either by DSCP (usually EF / 46) or by ports. The MX will put that traffic into the realtime or high priority queue.

No special firmware is required. Any current MX release supports this.

Keep in mind it mainly helps outbound traffic. Inbound depends on your ISP honoring DSCP. Best results come from wired links and correctly tagged voice traffic.