From: Vincent Mashburn (vmashburn@fedex.com)
Date: Tue May 23 2006 - 13:22:00 ART
Since you are trusting COS and not DSCP, the switch will use the
internal COS to DSCP map to determine the DSCP from the given COS. The
default COS-to-DSCP map is as follows:
Cos-dscp map:
cos: 0 1 2 3 4 5 6 7
--------------------------------
dscp: 0 8 16 24 32 40 48 56
as you can see, a COS of 2 maps to a DSCP of 16. So, if you want the
DSCP to remain the same value, change the COS-to-DSCP map.
Vince Mashburn
Voice / Data Engineer
901-263-5072
CCVP, CCNP, CCDA,Network +
Cisco IP Telephony Support Specialist
Cisco IP Telephony Operations Specialist
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
san
Sent: Tuesday, May 23, 2006 11:00 AM
To: GroupStudy CCIE
Subject: Switch Qos Basic Clarification
What will be the dscp & COS value of the outgoing packet ? for the
below
input. Could you please verify and confirm
Inter fas0/13
mls qos trust cos
Scenario 1:
Incoming frame is IP, where L3 Tos set to 40 & L2 Cos is set to 2
Answer:
Output cos => 2
Output dscp => 16 ((DSCP is overwritten here ?? ))
-- Thanks & Rgds SAN
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