QoS markings

[JOHN APONTE]

Need help please with the following problem.

6509a(our own) >3550 (carriers) to another carrier owned 3550 to >6509b (our own).

6509a WS-SUP720-BASE pfc3a

6509b WS-X6K-S2U-MSFC2 pfc2

A port on 6509a, WS-X6724-SFP, is set to trust dscp markings. The port is set as a dot1q trunk. A port on the 6509b,WS-X6416-GBIC, is set to trust dscp markings. The port is set as a dot1q trunk. The carriers 2 3550's are in between carrying the traffice between the 2 6509's. The carrier is doing Q in Q. QoS dscp marked 46 packet leaves 6509a to carriers 3550 but never makes it across to other 6509b switch. Unable to determine what is stripping off the marking. Tried also changing trust to cos but did not resolve issue. Carrier does not have qos enabled on their switches so packet should pass thru in their q in q tunnel not remarked. Packet capture does verify packet at least going in to their 3550. What could be stripping off the marking.? Thanks.

[Giuseppe Larosa · Accepted solution]

Hello John,

>> The trunk ports are set to trust dscp markings and not COS because the voip svrs are sending out a dscp 46 marking.

>> I guess I dont understand. I thought I am sending a tagged framed over the trunk..vlan 10? Is there a way to view the tagged raw frames to see the 802.1q header?

native vlan in 802.1Q is sent untagged unless you have an explicit option to send them tagged

this can be in part the cause of your problem as the provider switch expects to receive tagged frames to add the outer customer vlan-id (XXX) and to send the frame with double 802.1Q header to the other side.

Hope to help

Giuseppe

[JOHN APONTE]

Would changing these trunks to ISL make a difference?

[JOHN APONTE]

Changed the native vlan from 10 to 1 and it works!! We can see the markings on the other switch. Thanks for all your help!!!

[Giuseppe Larosa]

Hello John,

I'm happy to hear that it worked.

you have been kind to provide feedback this helps to improve the forums making this a complete story.

Best Regards

Giuseppe