QoS Groups Example

Quality of Service (QoS) groups are useful in scenarios where you have multiple interfaces and different traffic types.

They are particularly useful when you need standardized treatment of traffic, regardless of its ingress interface. QoS Groups act as a kind of label that is not part of the packet header itself, but is used to tag a packet for subsequent local QoS action.

For instance, in a network setup with two ingress interfaces:

  • GigabitEthernet0/1
  • GigabitEthernet0/2

You might want to classify ICMP traffic on GigabitEthernet0/1 and HTTP traffic on GigabitEthernet0/2.

Despite the different classification criteria, these traffic types can be assigned the same QoS group once inside the router, ensuring uniform processing.

This is achieved by using a common qos-group value for both traffic types and applying it in an egress policy-map. Here is an example:

class-map match-all ICMP
 match protocol icmp
class-map match-all HTTP
 match protocol http

policy-map INGRESS1
 class ICMP
  set qos-group 1

policy-map INGRESS2
 class HTTP
  set qos-group 1

interface GigabitEthernet0/1
 service-policy input INGRESS1

interface GigabitEthernet0/2
 service-policy input INGRESS2

class-map match-all QOS1
 match qos-group 1

policy-map EGRESS
 class QOS1
  set ip dscp ef

interface GigabitEthernet0/3
 service-policy output EGRESS

In the above configuration, the following was performed:

  1. Classify ICMP and HTTP traffic with class-maps.
  2. Assign a qos-group through ingress policy-maps for each interface.
  3. Use a class-map to match the qos-group, applying consistent treatment in the egress policy-map.

https://networklessons.com/quality-of-service/qos-marking-cisco-ios-router/