Hey Adam, As promised, here is the test you can do for the priority-queue out. (Double check me on this, since I don't come from a R&S background)
On my HQ Switch, I enabled auto qos on all the phone ports (trust phone) On the uplink port to HQ-RTR (for me is fas0/23) I set srr-queue bandwidth shape 65500 0 0 0 - which will make the effective bandwidth for queue 1 to about 2 b/s Make sure only cos 5 and dscp 46 is mapped to q1 thres 3, and all others are mapped somewhere else. At this point, we will test 2 scenarios on the uplink port. 1. With the priority-queue out command 2. Without the priority-queue out command But before we continue… Need to find your asic port number for the uplink port. Use the this command "show platform pm if-numbers" Then to see how many drops on that port, use this command. "show platform port-asic stats drop port 25" <-my fas0/23 = 25 (these commands are in the "Cisco Catalyst 3750 QoS Configuration Examples" at the very bottom) http://www.cisco.com/en/US/products/hw/switches/ps5023/products_tech_note09186a0080883f9e.shtml So on with the test... 1. With the priority-queue out cammand scenario Issue the priority-queue out command on the uplink port. Make calls from Hq1 to BR1 and Hq2 to BR2. Then run the show platform port-asic stat drop port # command again. Port 25 TxQueue Drop Statistics Queue 0 <- this is queue 1 Weight 0 Frames 0 Weight 1 Frames 0 Weight 2 Frames 0 <- no drops Queue 1 Weight 0 Frames 0 Weight 1 Frames 0 Weight 2 Frames 0 Queue 2 Weight 0 Frames 0 Weight 1 Frames 0 Weight 2 Frames 0 Queue 3 Weight 0 Frames 0 Weight 1 Frames 0 Weight 2 Frames 0 On the BR1 phones, press ? ? to see send / receive packets. they increment at the same rate. 2. Without the priority-queue out scenario remove the priority-queue out command Make calls again from 2 Hq phones to 2 BR1 phones. Then run the show platform port-asic command again. Port 25 TxQueue Drop Statistics Queue 0 Weight 0 Frames 0 Weight 1 Frames 0 Weight 2 Frames 3960 <===== voice packets dropping Queue 1 Weight 0 Frames 0 Weight 1 Frames 0 Weight 2 Frames 0 Queue 2 Weight 0 Frames 0 Weight 1 Frames 0 Weight 2 Frames 0 Queue 3 Weight 0 Frames 0 Weight 1 Frames 0 Weight 2 Frames 0 Supervisor TxQueue Drop Statistics On the BR1 phones, press ? ? again. You will see the RCVR packets either coming in really slow or none at all. Conclusion: Priority-queue out command will ignore what is configured on the shape for queue 1, and service that queue until empty, as doc says. The question then is: What is a "priority queue"? Not "priority-queue" or a "strict priority queue". the documentation does not mention priority queue for 3750 outside of enabling the priority queue out. In older switches the p-q was able to be rate limited. Wonder if the lab designers are using that assumption. Again check my sanity on this test. Thanks Sam
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