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How to verify Quality of Service (QoS) configuration is working on EOS products

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TitleHow to verify Quality of Service (QoS) configuration is working on EOS products
Objective
  • Verify QoS configuration on EOS devices
Environment
  • EOS
  • S-Series
  • K-Series
  • 7100-Series
  • All Firmware
Procedure
Generally speaking, it is not possible to directly verify the count of packets that enter into, drop from, or are transmitted from each of the hardware transmit queues of an EOS device.

That being said, here are some possibly helpful test procedures:
  • To determine whether configured ToS/Priority/VLAN reassignments are functioning, inject a known mix of ingress traffic and then analyze (with a "Sniffer") the mix of egress traffic. The transmitted ToS value will be apparent on IP frames, and the transmitted 802.1p Priority and 802.1q VLAN will be apparent if 802.1Q Tagging is enabled on egress (5811).
  • To gain insights regarding transmit queue (7584) behavior, perform a similar test after (a.) ensuring that any given priority is mapped to a unique transmit queue and (b.) ensuring that the injected traffic is of sufficient volume to over-subscribe the available transmit bandwidth (possibly reduced via Outbound Rate Limiting). Only lower-priority traffic should be dropped as necessary to conform with available bandwidth constraints, unless only higher-priority traffic remains to be dropped.
To verify the configuration is applied as intended, the following commands can be utilized:
  • The mappings of CoS queue to TXQ References can be verified with the 'show cos settings' command:
S4 Chassis(su)->show cos settings

 * Means attribute has not been configured

CoS Index  Priority    ToS      TxQ    IRL    ORL    Drop Prec Flood-Ctrl
---------  ----------  -------  -----  -----  -----  --------- ----------
0          0           *        0      *      *      *         Disabled
1          1           *        2      *      *      *         Disabled
2          2           *        4      *      *      *         Disabled
3          3           *        6      *      *      *         Disabled
4          4           *        8      *      *      *         Disabled
5          5           *        10     *      *      *         Disabled
6          6           *        12     *      *      *         Disabled
7          7           *        14     *      *      *         Disabled
  • The mappings of TXQ References to hardware queues can be verified with the 'show cos reference txq' command:
S4 Chassis(su)->show cos reference txq

Group Index Reference Type    Queue
----------- --------- ---- ------------
0.0         0         txq  0
0.0         1         txq  1
0.0         2         txq  2
0.0         3         txq  3
0.0         4         txq  4
0.0         5         txq  5
0.0         6         txq  6
0.0         7         txq  7
0.0         8         txq  8
0.0         9         txq  9
0.0         10        txq  8
0.0         11        txq  8
0.0         12        txq  8
0.0         13        txq  8
0.0         14        txq  9
0.0         15        txq  10
0.1         0         txq  0
0.1         1         txq  1
0.1         2         txq  2
0.1         3         txq  3
0.1         4         txq  4
0.1         5         txq  5
0.1         6         txq  6
0.1         7         txq  7
0.1         8         txq  8
0.1         9         txq  9
0.1         10        txq  10
0.1         11        txq  11
0.1         12        txq  12
0.1         13        txq  12
0.1         14        txq  13
0.1         15        txq  14
Additional notes
Paraphrased from Hub KB 5407, "How to Test a Quality of Service Configuration".

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