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C3750 dot1q-tunnel Qos problem

roman.g
Level 1
Level 1

Hello everybody.

Need your help with one problem. 

 

 <=> Cisco ME-C6524G  => Cisco WS-C3750-24TS => Cisco 3560

 

The ports between C6524 and C3750 Fa1/0/24  are trunk ports with allowed vlan 1500. Cisco C3750 port facing 3560 is configured as dot1q-tunnel port, while 3560 is trunk port with allowed vlan 600. The problem is that dscp markings are reset when passing through dot1q-tunnel port.  Between c6524 and c3750 dscp values are present. If i configure Fa1/0/1 on C3750 as trunk port with allowed vlan 600 then dscp values are also present between c3750 and 3560. Tried with both qos disabled and enabled with trust ports but no difference.

Why does the switch look in IP header?  Is any idea how to keep dscp values for c-vlan 600 unchanged?

Thank you!

 

C3750#

interface FastEthernet1/0/1
switchport access vlan 1500
switchport mode dot1q-tunnel

 

interface FastEthernet1/0/24
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1500
switchport mode trunk

 

C3750#sh mls qos
QoS is disabled
QoS ip packet dscp rewrite is disabled

 

System image file is "flash:c3750-ipservicesk9-mz.122-55.SE6.bin"

 

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