03-06-2019 09:04 AM
I have a 2960X that i have a VTC client plugged into. I'm running a sniffer on the VTC client and I see DSCP markings leaving the device with markings on it. On the switch itself I have a monitor session configured to mirror the VTC port and I'm sniffing traffic in that location too. The sniffer connected to the monitor port is NOT seeing any markings for DSCP?
Any idea on what could be causing this issue?!
SITE-OPS-AS-01#show mls qos QoS is disabled QoS ip packet dscp rewrite is disabled SITE-OPS-AS-01#
03-06-2019 09:57 AM
Can you post the mirrored logs to review.
03-06-2019 10:00 AM - edited 03-06-2019 10:50 AM
You'd like to look at the sniffer captures? The sniffer captures show the DSCP markings set to '0'. There is really nothing to show.
03-06-2019 12:01 PM
Like to offer couple threads already given good explanation :
https://community.cisco.com/t5/switching/qos-on-a-2960-with-no-outgoing-dscp/td-p/1669856
https://community.cisco.com/t5/switching/cisco-2960-change-default-dscp-value/td-p/911924
03-07-2019 01:05 AM - edited 03-07-2019 01:06 AM
Hello
@krogers wrote:
I have a 2960X that i have a VTC client plugged into. I'm running a sniffer on the VTC client and I see DSCP markings leaving the device with markings on it. On the switch itself I have a monitor session configured to mirror the VTC port and I'm sniffing traffic in that location too. The sniffer connected to the monitor port is NOT seeing any markings for DSCP?
Any idea on what could be causing this issue?!
SITE-OPS-AS-01#show mls qos QoS is disabled QoS ip packet dscp rewrite is disabled SITE-OPS-AS-01#
As the switch itself doesn't have qos enabled it cannot be the switch rewriting the dscp so I am thinking it could maybe your span session not sending/including them.
I am assuming your have a default local span session, if so could you try the following:
monitor session x source interface xxx tx
monitor session x destination interface xx encapsulation replicate
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