C2/B2 f/w x.02.13 Strict Priority configuration may not correctly reload

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Article ID: 14109 

Products
C2-Series, firmware 5.02.09.0003 through 5.02.13.0003
B2-Series, firmware 4.02.09.0003 through 4.02.13.0003 

Changes
Changed one or more ports from the default Weighted Round Robin (WRR) queueing to Strict Priority (STR) queueing; for example:
C2(su)->show port txq ge.1.1
Port Alg Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7
----- --- --- --- --- --- --- --- --- ---
ge.1.1 WRR 2 10 15 20 24 29 SP SP
C2(su)->set port txq ge.1.1 0 0 0 0 0 100
C2(su)->show port txq ge.1.1
Port Alg Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7
----- --- --- --- --- --- --- --- --- ---
ge.1.1 STR SP SP SP SP SP SP SP SP
C2(su)->
Symptoms
Though only the port's first six transmit queues (0-5) have been configured and queue 5 has been set to 100%, all eight queues (0-7) are shown in the configuration and queue 7 is shown as configured to 100%; for example:
C2(su)->show config port
This command shows non-default configurations only.
Use 'show config all' to show both default and non-default configurations.

begin
!
#***** NON-DEFAULT CONFIGURATION *****
!
!

#port
set port txq ge.1.1 0 0 0 0 0 0 0 100
!
end

C2(su)->
Cause
On the Stackable products - C5/C3/C2/B5/B3/B2/A4/A2-Series - for each port only six transmit queues (0-5) are configurable, while the two highest transmit queues (6-7) always operate in Strict mode. Thus, activity in queues 6-7 always overrides the lower queues. To ensure that internal stacking traffic always gets the service it needs, it is assigned to queues 6-7 and user traffic cannot be user-assigned to those queues ("Priority Queue out of range, valid range[0..5]") 

In contrast, on the related non-Stackable products - I/G/D-Series - for each port all eight transmit queues are configurable. 

Given that in all cases, setting a port to operate in Strict mode requres setting the highest configurable queue to 100% while the lower queues are left at 0%, this means that a different command would be used for each of the two sets of products:
Stackables-      set port txq <port#> 0 0 0 0 0 100
non-Stackables- set port txq <port#> 0 0 0 0 0 0 0 100
Further, in order for such a configuration to be offloaded ('show config outfile...') and then reloaded ('configure...') correctly (5623), the displayed configuration must accurately reflect the command that was originally issued. 

In the case of the issue under discussion in this C2/B2 document, the configuration reflects the non-Stackable command rather than the Stackable command. The hardware has been correctly programmed so this is generally harmless, except that if such an offloaded configuration were to be reloaded and parsed by the command editor, that line would error out rather than taking effect. 

Solution/Workaround
For the C2, upgrade to firmware 5.02.14.0002 or higher.
For the B2, upgrade to firmware 4.02.14.0002 or higher.
Release notes state, in the 'Firmware Changes and Enhancements' section:
15978   Corrected an issue with the "set port txq" command whereby the user defined settings were not properly applied to the configuration.

Pre-upgrade workaround:
Either correct the command directly in the saved config file before reloading it, or allow it to error out and then retype it into the switch configuration.
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Posted 5 years ago

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