The customer might have noticed some default CoS behavior after starting to install the ACX EVO platform.

The device is applying a default rewrite rule to any MPLS-enabled interface, which is overwriting the EXP bits and placing them into the best-effort queue.

- MPLS traffic is being classified into the best-effort queue regardless of its original EXP bit value.

- The default rewrite rule is automatically applied to MPLS-enabled interfaces, causing the loss of the original EXP bit values.

This behaviour is expected on the ACX platform. By default, any interface created is attached with default classifiers, and if any interface of family-type MPLS is created, the default EXP classifier and rewrite rules get applied. There is no hidden command to disable these default rewrite rules.