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Spirent KB Article
Doc ID: KNI17161
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Spirent TestCenter: 5.36 800G B2 appliance - 100G/200G/50G Configuring Manual Based scheduling mode at port level causes not to send at line rate
Configuring Manual Based scheduling mode on port level in 800G B2 appliance at 100G/200G/50G, causes a low TX rate and not sending at line rate, 400G works fine.
The ports should be sending at line rate as configured, however, it seems manual-based scheduling is causing this rate to decrease, changing it back to port-based works fine and ports send line rate.
NOTE: We have tested this in an SPT-CPB1 appliance and there is no issue with Manual Based Scheduling Mode, tested with 100G (Same speed B2 appliance shows the issue with)
The configuration tested this time is set with PPM -20, so we should be getting close to 99,998,000,000 and 99.998%, however, the ports configured with Manual Based scheduling is tx'ing at ~99,251,742,238 and 99.952%
Manual Based Scheduling Mode
Steps to reproduce:
Get some 800G B2 appliance ports and set them to either 50/100/200G
Create raw streamblock and set it to 100% load
Set port to Manual Based scheduling mode
Add at least one manual schedule entry
You will see Tx L1 Rate (bps) and Tx L1 Rate (Percent) is not line rate.
You can change the scheduling mode to port base mode and will see Tx L1 Rate (bps) and Tx L1 Rate (Percent) is now at line rate
Subject: 5.36 800G B2 appliance - 100G/200G/50G Configuring Manual Based scheduling mode at port level causes not to send at line rate
Date time opened: 11/1/2022
Date time closed: 11/13/22
Target release: 5.38 Release (December 2022)
Fix: FW programs non-zero values to the corresponding gap registers for manual scheduling.
Use Port Based scheduling mode instead
Sub-rates are different with 400G mode, need fw programs non-zero IFG, IEG and IBG values to corresponding registers.
Product : Spirent TestCenter