I have following setup
ALcatel box is acting as pure L2 switch carrying VLANs from CPE, I then trunk from ALcatel to 7609 where I terminate each VLAN in SVI.
I expect Alcatel switch to remark inbound CPE traffic. however, only COS bit is remarked. when packets hits the 7609 and tag is stripped off remarking by Alcatel has obviously no effect.
if I was using a Cisco instead of ALcatel, een as L2 I woudl expect COS bit to eb copied to DSCP bit.
I would hate to remark on 7609 ( distribution layer). does anyone have any recommendations ?
Assuming the Alcatel marks/trusts by default, and you are trunking on the 7609 (sounds like you are since you mentioned it terminates at an SVI), then you should only need to trust CoS on the trunk port going to the Alcatel.
In hardware when the 802.1Q tag is stripped off all the information is copied to a header internal to the switch, including the CoS marking. If we trust CoS and there is a CoS marking, we'll write in the appropriate DSCP in the IP header as per the CoS-to-DSCP mapping.