QOS on 3850 vs 2960

[david.klein]

We have Shoretel/Mitel VOIP IP phone system.  I am wondering how I should be adding QOS to a 3850 switch vs a remote site 2960 switch?  What does the configuration look like on 3850 vs 2960?

2nd Question.  When implementing QOS through your network, I've been told 2 different things as far as the trunk ports/etherchannels going from Core to 3850 switches in our environment.  I have been told you need to add QOS to trunk port and also been told that you do not need it on the trunk port????

3rd Question.  What is the best way to investigate that QOS is happening?  I am assuming wireshark but want to know if I am looking for EF on frame and where am I looking for that?  Should I only see it on the port connected to the Shoretel Phone on the 3850 switch, or if QOS is being added to the trunk ports all the way through, to the core 6880 in our environment, then will I see this on the trunk port on 6880 which is connected to the 3850 switch that the user is on?

Thanks in advance

Dave

[omz]

My understanding is that QoS should be enabled end-to-end including the trunks. Any hop not doing the QoS or stripping the QoS marking will have a negative impact.

In the pcap you can check markings in the ToS byte. 

[Giuseppe Larosa]

Hello Dave,

an effective QoS design requires to implement it end to end.

Access layer devices should mark the VOIP traffic with EF DSCP value in order to be processed in low latency queue in all outgoing interfaces in the path.

Qos Configuration on Cisco 3850 is different then that of C2960.

C3850 supports modular QoS like routers.

see the link below

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/16-9/configuration_guide/qos/b_169_qos_3850_cg/configuring_qos.html#concept_D7931FA2AF3D4F4B8F537910915F6C48

It uses ACLs, class-maps and policy-maps that are then applied to the interfaces with command

service-policy <QoS-policy-name> in/out in interface configuration mode.

To monitor QoS operation on the C3850 you can use

show policy-map interface <interface-name>

it provides statistics for each traffic class defined

Edit:

for the Cisco 2960 QoS features support depends on model

C2960-L does not support class-maps

see

https://content.cisco.com/chapter.sjs?uri=/searchable/chapter/content/en/us/td/docs/switches/lan/catalyst2960l/software/15-2_5_e/config-guide/b_1525e_consolidated_2960l_cg/b_1525e_consolidated_2960l_cg_chapter_011010.html.xml&searchurl=https%3A%2F%2F...

C2960 XR looks like to support at leat modular QoS for marking but still use "hardware based " SRR queueing on exit interfaces

see

https://content.cisco.com/chapter.sjs?uri=/searchable/chapter/content/en/us/td/docs/switches/lan/catalyst2960xr/software/15-2_2_e/qos/configuration_guide/b_qos_1522e_2960XR_cg/b_qos_152ex1_2960-xr_cg_chapter_010.html.xml&searchurl=https%3A%2F%2Fsearc...

So C2960 QoS implementation is quite different and can be monitored using different commands.

Hope to help

Giuseppe