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AutoQoS on Catalyst 2900 & 3560

chris.berry.1
Level 1
Level 1

Cisco C2960S IOS:12.2(55)SE5

Cisco C3560X IOS: 12.2(55)SE3

The 3560 switch is serving as an access and distribution layer switch. End devices are connected to it and it also implements IP routing via SVI and L3 ports.

Auto qos voice cisco-phone has been implemented on applicable access layer ports. SRND4 is being used.

2960:

mls qos map policed-dscp  0 10 18 24 46 to 8

mls qos map cos-dscp 0 8 16 24 32 46 48 56

mls qos srr-queue output cos-map queue 1 threshold 3 4 5

mls qos srr-queue output cos-map queue 2 threshold 1 2

mls qos srr-queue output cos-map queue 2 threshold 2 3

mls qos srr-queue output cos-map queue 2 threshold 3 6 7

mls qos srr-queue output cos-map queue 3 threshold 3 0

mls qos srr-queue output cos-map queue 4 threshold 3 1

mls qos srr-queue output dscp-map queue 1 threshold 3 32 33 40 41 42 43 44 45

mls qos srr-queue output dscp-map queue 1 threshold 3 46 47

mls qos srr-queue output dscp-map queue 2 threshold 1 16 17 18 19 20 21 22 23

mls qos srr-queue output dscp-map queue 2 threshold 1 26 27 28 29 30 31 34 35

mls qos srr-queue output dscp-map queue 2 threshold 1 36 37 38 39

mls qos srr-queue output dscp-map queue 2 threshold 2 24

mls qos srr-queue output dscp-map queue 2 threshold 3 48 49 50 51 52 53 54 55

mls qos srr-queue output dscp-map queue 2 threshold 3 56 57 58 59 60 61 62 63

mls qos srr-queue output dscp-map queue 3 threshold 3 0 1 2 3 4 5 6 7

mls qos srr-queue output dscp-map queue 4 threshold 1 8 9 11 13 15

mls qos srr-queue output dscp-map queue 4 threshold 2 10 12 14

mls qos queue-set output 1 threshold 1 100 100 50 200

mls qos queue-set output 1 threshold 2 125 125 100 400

mls qos queue-set output 1 threshold 3 100 100 100 400

mls qos queue-set output 1 threshold 4 60 150 50 200

mls qos queue-set output 1 buffers 15 25 40 20

mls qos

3560:

mls qos map policed-dscp  0 10 18 to 8

mls qos map cos-dscp 0 8 16 24 32 46 48 56

mls qos srr-queue input bandwidth 70 30

mls qos srr-queue input threshold 1 80 90

mls qos srr-queue input priority-queue 2 bandwidth 30

mls qos srr-queue input cos-map queue 1 threshold 2 3

mls qos srr-queue input cos-map queue 1 threshold 3 6 7

mls qos srr-queue input cos-map queue 2 threshold 1 4

mls qos srr-queue input dscp-map queue 1 threshold 2 24

mls qos srr-queue input dscp-map queue 1 threshold 3 48 49 50 51 52 53 54 55

mls qos srr-queue input dscp-map queue 1 threshold 3 56 57 58 59 60 61 62 63

mls qos srr-queue input dscp-map queue 2 threshold 3 32 33 40 41 42 43 44 45

mls qos srr-queue input dscp-map queue 2 threshold 3 46 47

mls qos srr-queue output cos-map queue 1 threshold 3 4 5

mls qos srr-queue output cos-map queue 2 threshold 1 2

mls qos srr-queue output cos-map queue 2 threshold 2 3

mls qos srr-queue output cos-map queue 2 threshold 3 6 7

mls qos srr-queue output cos-map queue 3 threshold 3 0

mls qos srr-queue output cos-map queue 4 threshold 3 1

mls qos srr-queue output dscp-map queue 1 threshold 3 32 33 40 41 42 43 44 45

mls qos srr-queue output dscp-map queue 1 threshold 3 46 47

mls qos srr-queue output dscp-map queue 2 threshold 1 16 17 18 19 20 21 22 23

mls qos srr-queue output dscp-map queue 2 threshold 1 26 27 28 29 30 31 34 35

mls qos srr-queue output dscp-map queue 2 threshold 1 36 37 38 39

mls qos srr-queue output dscp-map queue 2 threshold 2 24

mls qos srr-queue output dscp-map queue 2 threshold 3 48 49 50 51 52 53 54 55

mls qos srr-queue output dscp-map queue 2 threshold 3 56 57 58 59 60 61 62 63

mls qos srr-queue output dscp-map queue 3 threshold 3 0 1 2 3 4 5 6 7

mls qos srr-queue output dscp-map queue 4 threshold 1 8 9 11 13 15

mls qos srr-queue output dscp-map queue 4 threshold 2 10 12 14

mls qos queue-set output 1 threshold 1 100 100 50 200

mls qos queue-set output 1 threshold 2 125 125 100 400

mls qos queue-set output 1 threshold 3 100 100 100 400

mls qos queue-set output 1 threshold 4 60 150 50 200

mls qos queue-set output 1 buffers 15 25 40 20

mls qos


I understand that the 2960 does not support ingress queuing.

Question 1:Why is the auto qos generated policed-dscp map different on these two switches?

The Cisco Smart Business Architecture LAN configuration files guide (http://www.cisco.com/en/US/docs/solutions/SBA/August2012/Cisco_SBA_BN_LANConfigurationFilesGuide-Aug2012.pdf) does not specifically use the 3560 in their examples, they use the 3750 but it's my assumption that the same techniques, configs apply with regard to my specific feature questions. When using a 3750 in the Access layer, the guide shows (page 15) the same auto qos generated policed-dscp map configuration that is on my 2960. The SBA LAN config guide shows that when using a 3750 as a Distribution layer switch (page 26), the policed-dscp map configuration is the same that I see on my 3560.

In the configuration guide for the 3750 distro switch, there is no auto qos applied as there are no access ports, so the mls qos commands are manually input. Since my 3560 does have access ports, auto qos generated the mls qos commands, and the results are the same be it following the guide and manually entering (per distro switch guidelines) or using auto qos. This leads to question 2...

Question 2:Why is the mls qos map policed-dscp configuration different depending on use as an access vs. distribution switch?

Question 3: On the 3560, access ports that have "auto qos voice cisco-phone" applied are put into queue-set 2 (output). Queue-set 2 (output) uses default values (not configured). Is this correct and desirable? If so, why? The 2960 has all ports in queue-set 1, regardless of being an access device port or a trunk port connected to the 3560 (as per the SBA LAN config guide EgressQOS macro commands). The 3560 trunk ports are all also configured to use queue-set 1 (output), again as per the SBA LAN config guide EgressQOS marco commands.

I very much appreciate your assistance and answers.

1 Reply 1

chris.berry.1
Level 1
Level 1

Continuing my reading and investigation, the global commands generated on the 3560 appear to be using the "enhanced" version of Auto QoS. Applicable information starting on page 37-25:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750x_3560x/software/release/12.2_55_se/configuration/guide/swqos.pdf

Can anyone confirm this? And is enhanced AutoQoS synonymous with "auto qos srnd4"?

Page 37-26: "Auto-QoS migration happens after a new device is connected when the

auto qos srnd4 global configuration command is enabled."

Will access interfaces on the 3560 which use queue-set 2 (not configured/using defaults) at present migrate to using queue-set 1 once a a new device is connected? If enhanced QoS has been deployed since the start of the switch's configuration, why was queue-set 1 not used from the beginnging? Please see my original question #3.

The 2960 looks to also be using the "enhanced" auto QoS commands... but the policed-dscp does not conform with that theory. For both switches, based upon the documentation, it seems as if the policed-dscp should be 0 10 18 to 8. Everything else appears to be using the enhanced AutoQoS configuration. How does all of this fit in with my original questions 1 & 2?

Your input is greatly appreciated.

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