Legacy Scheduler / Data Channel QoS / VLAN Remarking

Does anyone have experience or advice on using VLAN remarking and data channel CIR to protect high priority traffic?

We are attempting to use remarking to prioritize SCADA traffic (on VLAN 800) on our PMP450i system.
We seem to be successful on the uplink but not on the downlink.

This is for a municipal network. There are other sites and applications on the system and it’s okay to throttle them if it’s necessary to protect the SCADA traffic. However with current traffic I’m not expecting throttling to happen. Frame utilization on the AP is typically less than 30% but we want to build some protection for SCADA traffic into the system to allow for future growth. The total SCADA traffic amounts are low so we can assign a small CIR to the data channels that SCADA uses without cutting much into the bandwidth that is available to other types of traffic. For example we’re testing with…

  • 4 data channels. We have assigned a CIR of 100 kbps assigned to the high priority data channel
  • Remark VLAN 800 802.1p = 5 (to direct traffic to the high priority data channel)

By looking at Statistics → Data Channels we can see that the SCADA traffic appears on the high priority data channel when we implement the above configuration.
This works when we apply remarking at the SM. SCADA traffic is blocked when we also apply remarking at the AP.

This all uses the Legacy Scheduler - the ability to apply CIR to a data channel seems like a good fit for what we’re trying to accomplish.

Are there any problems with what we’re planning or any errors in my understanding? Any idea why the connection breaks when we apply remarking at the AP end?