Prioritizing Traffic within Meraki Full Stack

[Brash]

I'm looking at lowering the priority of some traffic within one of our environments due to concerns about overwhelming the outbound Internet bandwidth.

Per client bandwidth limits are already set.

However I'm looking to lower the priority on network traffic from clients on that specific subnet.

I know I can do this with traffic shaping rules but I'm just trying to understand whether there's any difference between where the shaping rule is applied.

For example, the following link described applying on the MX which carves up the uplink traffic. Is this the same behaviour as if I apply the shaping rule on the SSID/Group Policy?

Using Packet Prioritization on a Traffic Shaping Rule - Cisco Meraki

[alemabrahao]

Theoretically yes.

[rdominguez]

Hello @Brash. The location of the rules shouldn't affect the behavior. Making sure that all of the DSCP tags are uniform across the network is the main area of concern. 

[Brash]

Thanks for the responses.

This probably made sense for everyone else immediately but took a little for me to work through the differences in where what can be applied.
Below are some clarifications for myself or anyone else confused to reference.

When performing traffic shaping, there are 3 places in which it can be applied:

 - MR (per SSID) - Apply CoS and DSCP tags

 - Group Policy - Apply CoS and DSCP tags

 - MX - Apply DSCP tags or 'Priority' (referenced in docs as Packet Prioritization)

CoS tags are applicable within an L2 network.

DSCP tags are applicable when crossing L3 boundaries.

This makes sense, but what confused me was 'priority' on the MX.

This is applicable only to uplink bandwidth and when enabled, portions out the uplink bandwidth accordingly (see link below).

Using Packet Prioritization on a Traffic Shaping Rule - Cisco Meraki

It's only effective if the WAN bandwidth in the Uplink Configuration is accurately configured:

For my use case therefore, a combination of each of these is applicable.

[Brash]

One other thing I'll add here:

 If a group policy is set with "ignore traffic shaping and bandwidth", this doesn't place the traffic into the Normal priority but rather it gives it a high priority making it impossible to limit on the uplink.

This defect was confirmed by support but understandably has no resolution date given how niche it is.