Simplified QoS on 3850 with MQC
Configuring QoS has been much improved in Cisco’s new 3850 line of switches thanks to its implementation of MQC (Modular QoS Cli) configuration instead of the old “mls qos” commands from the 3750 and 3560 lines of switches. Here I will show just how easy it is to generate a simple QoS config to handle voice and video traffic.
First we define what traffic we would like to work with. In this case it is voice traffic marked as dscp ef and video traffic marked as dscp af41.
Easy enough. Now lets configure the policy maps to actually do something with this traffic. I will configure two separate policy maps. one for user facing ports and one for the uplinks to my distribution layer.
I would like to prioritize both voice and video traffic over everything else but I want voice to be prioritized over everything. The 3850 actually has 2 priority queues that enable me to do this, a level 1 and level 2 priority queue.
Above I have separate policy maps based on if it’s a user or uplink port. For user ports, voice traffic is put in priority queue 1 and guaranteed 1% or 10Mbps of throughput. I also capped it at 10Mbps with the police command to prevent this queue from hogging bandwidth. Same process is followed for voice. It is placed in priority queue 2 and it is guaranteed 50Mbps throughput. On the uplinks, the only change is the percentages of guaranteed bandwidth has been increased.All other traffic gets 100% of the remaining bandwidth.
All that is left is to apply these policy maps to some interfaces.
Done! We can even get some meaningful stats now as well. I haven’t pushed any traffic through this switch yet but you get the idea.
As you can see pretty painless QoS implementation. Of course you can get much more complicated if needed with nested policy-maps, table maps etc. Here is the IOS-XE QoS documentation if you want to delve further into QoS IOS XE QoS Config Guide”