Can L3 switch buffer packets into proper input queue based on DSCP not cos?

ciscoforum · ‎06-08-2007

Does anybody know that L3 switch can put the voice packets into the proper input queuing based on dscp? As I know that L2 switch does this based on cos value. I have 2821 GW connects to 6500 IOS image switch. It's not dot1q trunk. so there is no cos. Then rtp from the GW won't be able to assigned into proper input queuing if it's based on L2 cos value. Thanks

smalkeric · ‎06-14-2007

Modify the CoS-to-DSCP mapping. The recommended settings are DSCP = CS3 (24) for voice-over-IP (VoIP) control and DSCP = EF (46) for VoIP media traffic. To map the Layer 2 CoS correctly to these DSCP values, you must modify the switch default CoS-to-DSCP mappings. All CoS are shown though only 0, 3, and 5 are directly related to IPT.

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008014a29f.shtml

ciscoforum · ‎06-14-2007

Thanks. But my question is that the GW connects to the 6509 directly with the non-dot1q trunk connection(just an access port).So there is no cos in the layer 2, only has dscp. Then how the Cat Os able to assign the voice packet into proper queueing?

Here is the topology

analog phone-PBX-PRI-GW-6509---fiber-wan-6509-GW-PRI-PBX-analog phone