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Ethernet Switches & Routers

New Contributor
Posts: 3
Registered: ‎03-29-2016

General QoS Question



We have a stack of ICX-7750 switchs at our core and ICX-6450 switches at our edge.  Our ShoreTel UC system has always indicated that we've had execssive packet loss and delay.  We've configured our ICX-7750 "trust" the DSCP markings being received by our edge switches and we've confirmed that the DSCP markings are seen end to end.  


We have not configured anything OTHER than the "trust" settings on the ICX-7750 and the DSCP markings on the edge/ICX-6450 switches.  We were lead to beleive that everything else was already setup/pre-configured on the ICX switches.  I found that the ICX-7750 is using a "mixed weighted priority with strict priority" qos-profile while the ICX-6450 are using "weighted priority" qos-profile.  


The DSCP markings of 46 map to queue 5 on both systems, but on the ICX-7750 queue 5 receives 25% of the bandwidth, with queue 6 and 7 having strict priority.  On the ICX-6450 queue 5 only receives 3% of the bandwdith, with queue 7 receive 75% of the bandwidth.  Furthermore, on the ICX-7750 I can see counters for the individual "egrees queues", but on the ICX-6450 the "egress queue" counters are all "0".  In other words to me it seems like the ICX-7750 is placing packets in different queues, but the ICX-665 is not.


My fear is that the ICX-6450 is not actually enforcing QoS and if it is that we are not alotting enough bandwdith to queue 5.  Can anyone tell me if what I am seeing is normal?  On the ICX-7750 we added the "trust dscp" command to all the ports and on the ICX-6450 we've added the "ip dscp-remark 46" command to all the voice ports.  Our voice equipment has its own VLAN too.





Former Brocadian
Posts: 103
Registered: ‎04-07-2011

Re: General QoS Question

Hello @aalara


I see that you had a TAC case opened for this issue - I hope you got the assistance you needed?


If there's anything further we can do for you via the Community, please let us know.


Best Regards,


Denise K.

Brocade Community Team


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