User's Manual

Quality of Service (QoS)

Horizon Compact Plus Release 1.0.1 Wireless Ethernet Product User Manual – Volume 2

8.4 Operation with QoS Enabled

In Horizon Compact Plus, when QoS is enabled, a configurable packet filter directs user data packets to

any one of eight QoS queues based on the CoS (priority) levels assigned to each packet. The eight QoS

queues are labeled Q1 to Q8.

Slow bridge protocol frames, by default, are directed to the highest priority queue Q8, however, if QoS is

enabled, these frames can be directed to any one of the eight QoS queues.

Similarly, if QoS is enabled, any ECFM frames arriving from the network (not originating on the Compact

Plus) can be directed to any one of the eight QoS queues. If the ECFM feature is enabled on the node,

ECFM flow mapping is overridden and all ECFM frames are directed to the CPU.

Traffic statistics for each queue (Q1 to Q8) can be viewed using get traffic statistics.

8.4.1 Assigning User Data to QoS Queues

There are eight QoS Queues within Horizon Compact Plus, numbered Q1 to Q8, with Q8 having the

highest priority. On any port any of the eight CoS levels can be assigned to any of the eight QoS

Queues. A configurable packet filter (set cos queue mapping [mapping]) directs frames to the assigned

QoS queue based on the CoS level of that packet. You can configure the system so that packets with a

higher CoS level would be directed to a higher queue number.

Any packet arriving with no CoS level assigned to it can be assigned a level (0 – 7) based on the

configured default CoS value (set cos default value [0 though 7). This CoS level is stripped from the

packet after processing through the QoS system.

Once queues are populated with packets, a “scheduler” is responsible for moving queued packets out of

the queues in a specific order. The scheduling policy decides the behavior of the scheduler.

8.4.2 Slow Bridge Protocol Frames

Slow bridge protocol frames are those that are destined for the 01-80-C2-00-00-xx MAC addresses.

Examples: STP, RSTP, MSTP LACP, Pause Frames, GARP (GMRP,GVRP), bridge broadcasts, OAM,

LLDP, Port based authentication, are all transmitted in an expedited fashion.

By default, slow bridge protocol packets are handled by queue Q8. Q8 is the highest priority queue in the

system and it ensures slow bridge protocol packets are passed at the highest priority.

However, when QoS is enabled, Compact Plus can also be configured to direct slow bridge protocol

packets to any one of the eight QoS queues, allowing the user to control the priority of slow bridge

protocol packets. This feature is called Class of Service Control Flow Mapping. If this feature is not

configured, then slow bridge protocol packets are directed only to Q8, regardless of the status of QoS.

Similarly, when QoS is enabled, Compact Plus can be configured to direct ECFM frames arriving over the

network (not generated on the node) to any one of the eight QoS queues, allowing the user to control the

priority of the ECFM frames. This feature is called Class of Service ECFM Flow Mapping. Note that this

feature is overridden if the ECFM feature on the node is enabled and all ECFM frames would be directed

to the CPU.

Other frames, such as “keep-alive” frames and MRP frames, that the user determines must be treated

with a desired priority, must be assigned a CoS within a connected switch, then assigned to the

appropriate QoS queue within Horizon Compact Plus.

Note that you have to be carefull assigning regular user traffic to Q8 as that may starve the slow

protocol/ECFM traffic flow if those flows are assigned to Q8.