Qos on uplinks

[Mac1]

Say I've marked my access vlans with whatever qos markings.

The lacp uplinks they just need "Trust incoming dscp". Yes?

[ww]

As soon as the first QoS rule is added, the switch will begin to trust DSCP bits on incoming packets that have a DSCP to CoS mappings. This rule is invisible and processed last.

https://documentation.meraki.com/MS/Other_Topics/MS_Switch_Quality_of_Service_Defined#How_is_DSCP_ta...

[Mac1]

So, if I apply a qos rule, fopr a particular Access port, are you saying that the trunk ports for the uplink will automatically honour this, or should these Trunk ports be configure with Trust DSCP?

Is that right or not what about the uplinks please?

[GIdenJoe · Accepted solution]

The logic is applied on the whole network not individual ports.

Meraki switches also only use DSCP values to set or trust, not L2 markings.

So incoming traffic is marked or trusted according to the setting you applied on the page, if that traffic happens to arrive on an access port to a user or a trunk incoming from another meraki or non-meraki switch, the logic remains the same.

Outgoing traffic then uses the queueing mechanism if buffering is needed according to the DSCP to CoS mapping.

So again on access ports or trunks to other switches, if your DSCP is mapped to CoS queue 3 it will then be serviced 8x longer than queue 0.

[Mac1]

Brilliant. Thanks everyone for your help.

[GIdenJoe]

Btw the QoS rules apply to any Meraki switchport in your network. You can't really select ports to apply the policies to.