MPLS QoS

[Bekzod Fakhriddinov]

Hi, we have lan switches 9300 and mpls between them, everything is internal LAN. 

Does it make sense to add " auto qos trust dscp" on the connected interfaces btw those switches? 

As I read mpls does carry 3 bits of dscp into packet, but not sure do i need additional commands for it, and how/what switch will process first on the incoming packet. 

thank you 

[Sergey Lisitsin]

Bekzod,

Configuring these ports to trust DSCP means that they will have to read packet up to layer 3 to get to the DSCP information. Also, I think that QoS trust boundaries should be configured on the edge of MPLS network, not within it. Inside the network all kinds of markings should be trusted, because they should be checked and if need be overridden at the edge.

[Bekzod Fakhriddinov · Accepted solution]

"Inside the network all kinds of markings should be trusted," that's why i am adding auto qos trust dscp on every switch up/downlink, but some of them are L3 and mpls on it, even there are in LAN and not connected to WAN. I found mpls can read dscp and use first  3 bits of dscp into EXP field on the frame.  SO most likely auto qos trust command will not harm and dscp will be transferred btw these mpls LAN ports.