QoS port priority EOS

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given the following configuration:


D2(su)->show cos state
Class-of-Service application is enabled


D2(su)->show cos settings
CoS Index Priority ToS IRL flood-ctrl
--------- ---------- ------- ------- ----------
0 0 * * enabled
1 1 * * enabled
2 2 * * enabled
3 3 104 * enabled
4 4 * * enabled
5 5 184 * enabled
6 6 * * enabled
7 7 * * enabled

D2(su)->show port priority ge.1.5
ge.1.5 is set to 3
D2(su)->show port txq ge.1.5
Port Alg Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7
----- --- --- --- --- --- --- --- --- ---
ge.1.5 WRR 2 5 7 10 12 15 20 29

D2(su)->show port priority-queue ge.1.5
Port P0 P1 P2 P3 P4 P5 P6 P7
--------- -- -- -- -- -- -- -- --
ge.1.5 2 0 1 3 4 5 6 7

I would expect that untagged traffic ingressing in ge.1.5 will be assigned a priority of 3
and it will carry this when egressing as a tagged frame.
This behaviour was confirmed with wireshark; tagged frames egressing carry a priority of 3.

The question now is, does the traffic get to Q3 and is it forwarded according to the txq rules (10%) of all ???

Is there any way to confirm the COS configuration ??

Also ist it enough to have the ToS/CoS mapping in the cos settings to priorize AF31 and EF or ist policy a must at this stage ??
The devices are sending DSCP mared traffic, the PBX does not, thats the port priority conf.

TIA.
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Holger Gmerek

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Posted 3 years ago

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French, Luke, Employee

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There is no way to confirm the QoS internal to the D2.
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Holger Gmerek

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Hi Luke,
thanks for your reply, i thought that there is no way of monitoring this.

But it seems that is only a partial answer to my questions.
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French, Luke, Employee

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Sorry, I'm not sure about the rest.  Lets give the community a chance to answer.  If you don't get an answer on this, open a ticket with the GTAC.
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Paul Poyant, Employee

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The port txq settings represent the minimum guaranteed percentage of available Weighted Round Robin service (total = 100) that will be dedicated to that port's packet transmission, as needed.
The port priority-queue settings represent the actual hardware transmit queue number (for the D2, 0 through 7 exist) used for each of the possible packet priorities 0 through 7. 
Here, these all appear to be set at their defaults.

"I would expect that untagged traffic ingressing in ge.1.5 will be assigned a priority of 3 and it will carry this when egressing as a tagged frame."
Yes, true - as you've determined.

"Does the traffic get to Q3 and is it forwarded according to the txq rules (10%) of all?"
Yes.  But understand that it's only restricted to 10% if the higher-priority queues are demanding full attention.  It's possible that in effect, Q3 could receive 100% of the service.

"Is there any way to confirm the COS configuration?"
As already stated, officially the answer here is No.

"Is it enough to have the ToS/CoS mapping in the cos settings to priorize AF31 and EF or is policy a must at this stage?"
By default, none of this examines or cares about the TOS/DSCP settings of incoming frames.  
On the D2 without a Policy license, one could use Diffserv (outlined in Hub KB 5848, http://bit.ly/18F0WPL) to act upon DSCP settings.
On the D2 with a Policy license, one could use Policy (for example Hub KB 7589, http://bit.ly/18ffoh8) to act upon DSCP settings.

Questions?
(Edited)
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Paul Poyant, Employee

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Also note that in the 'show cos settings' output, the two numeric values in the ToS column would be used for the purpose of doing "TOS Rewrite" upon egress, rather than being used for recognizing TOS values upon ingress as you are seeking here. Hub KB 5810 (http://bit.ly/1lDhQjj) provides a detailed N-Series TOS Rewrite discussion that in principle - with some minor hardware-based differences - applies to the policy-licensed D2 as well.

By default the D2 (and N-Series) would carry any TOS byte values through, from ingress to egress. In general it is not necessary to reinforce this via TOS Rewrite.
(Edited)
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Paul Poyant, Employee

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Here's further discussion on the EOS "CoS confirmation / QoS testing" front...
how_to_test_a_quality_of_service_configuration
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Holger Gmerek

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Thanks Paul for your fast and detailed answer, as always.
So since i have Unify(Siemens) phones that mark their traffic with TOS/DSCP and not L2 priority i have to do the ToS/CoS mapping via policy upon ingress. Since i have also B5 and C5 i will not use the diffserv command set.

Thanks Holger
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Paul Poyant, Employee

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You're welcome, Holger.
Yes, D2 / B5 / C5 Policy should work fine here, and the discussion is 97% similar for all.