Where are DSCP values applied to video traffic?
A. DSCP can be set only on the video endpoint itself to ensure that the correct value is sent
B. DSCP is configured under service parameters in Cisco Unified Communications Manager and in the Expressways
C. DSCP can be configured only in the network with QoS policies
D. The endpoint overrides the DSCP values configured anywhere else
E. DSCP is configured in the device configuration section of Cisco Unified Communications Manager and in the Expressways
SRND:
For trusted and conditionally trusted endpoints, the DSCP marking of packets on ingress into the switch
are trusted and rewritten to the same value on egress.
For CDP-capable Cisco IP Phones, Cisco CTS, Cisco IP Video Surveillance cameras, and Cisco Digital
Media Players (as opposed to software clients such as Jabber), we recommend using the CDP conditional
trust and passing the marking of the trusted endpoint through the network. When electing to trust Cisco
IP Phones, you must trust CoS because the phones can re-mark only PC traffic at Layer 2. Trusted
endpoints derive their DSCP marking from Unified CM. DSCP for endpoints is configured in the
Unified CM service parameters under Clusterwide Parameters (System – QoS).
I can’t understand this question, QoS must be applied to all the devices involved in a route.
I agree with answer D;
the values configured in an endpoint statically overrides the DSCP values configured anywhere else. The new value overrides the service parameter setting.
After extensively researching this, I believe C is the correct answer, as Tony said.
The DSCP values you configure in CUCM service parameters are how the QoS DSCP are MARKED, not how they are treated/applied. They do not get any treatment/application until they enter the network at the switchport. That is where you configure the QoS treatment levels. So C is correct.
I think that the key word is applied: “…where it is applied”.
Because, an audio/video End point can mark it’s traffic with whatever value it wants, but the policy is applied at the switch with QoS Policies.
That is why i think the answer is C
Why C.
You can also configure DSCP marking in service parameters in CUCM