Traffic shaping without Uplink configuration set properly

[harmankardon]

This question is probably a mix of traffic shaping theory and Meraki specific behavior:

What is the impact on traffic shaping if the WAN uplink configuration (upload and download bandwidth) is not configured properly? For example, on a MX67C with a 100Mbps down / 100Mbps up internet connection, what happens if the sliders are not set to match that and instead are set to the max slider value of 600Mbps? Do these sliders need to be set accurately (or perhaps slightly below the actual values) in order for traffic shaping to be effective?

And as a follow-up, is there really any ability to shape traffic on the download side or is it essentially all on the upload side?

[RaphaelL]

If you only have 1 WAN connection and the slidder isn't set to the proper value , the MX won't be able to know the link speed and may try to push more than the link can handle which may result in latency / packetloss. 

If you have more than 1 WAN connection it is also used to load balance traffic according the speed of both WAN.

https://documentation.meraki.com/MX/Firewall_and_Traffic_Shaping/SD-WAN_and_Traffic_Shaping

[harmankardon]

Thanks, the multiple WAN connections seems like a pretty straightforward case. I should have specified just a single WAN connection in my case.

If the link becomes statured, will the MX not recognize that and attempt to perform some degree of traffic shaping? I would imagine the TX queues would fill up and that would give the MX something to act on, but I'm just guessing.

[Ryan_Miles]

https://documentation.meraki.com/MX/Firewall_and_Traffic_Shaping/Using_Packet_Prioritization_on_a_Tr...

[harmankardon]

Thanks @Ryan_Miles How is this impacted if the link speeds are not set correctly?