I have a video device attached to a 6509. It markes voice packets with DSCP46. The blade supports only cos to queue mapping. If I trust the DSCP on that port will it work? How does it decide in qwich queue should it go if the mapping is based on COS?
This 6500 is connected to a 3750 which has another video device attached. When I do "show queueing interface" I get this:
EMHBSSWFE2#sh queueing interface GigabitEthernet1/0/27
Interface GigabitEthernet1/0/27 queueing strategy: none
Here is the interface config:
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1,20,30,40,199-201
switchport mode trunk
srr-queue bandwidth share 10 10 60 20
mls qos trust dscp
auto qos voip trust
channel-group 1 mode on
Any help is apreciated ;-)
Ingress scheduling is not utilised if you do not trust COS on the interface on the 6500, however if you do trust DSCP the egress port scheduling will still be utilised by deriving the cos value from the DSCP using the default dscp-cos mappings.
By default tail-drop will be used unless WRED is specifically configured, but this is dependand on the port capabilities on the given module.
Regardless of whether the video attached device is marking packets with DSCP it should be placed in the appropriate transmit queue. When you enable 'mls qos' dscp 46 will be mapped to cos 5, ordinarily it should be assigned to cos 4. Therefore I assume it is the device which setting the DSCP.
The trouble with setting video with DSCP46 will mean it will share the priority queue with voice rtp which may or may not be desired?
If the later is the case then I would be inclinded to configure the access port for the video device to with cos 4 'mls qos cos 4'
Run the 'show queueing interface ?/?' on the 6500 and it will show you the default cos egress queue maps.