Re: MLS QoS issue on Catalyst 3560cx

rasmusan1 · ‎12-19-2018

Hello

I have an issue with MLS QoS on catalyst 3560cx platform... not sure why behaviour is like this.

I have done mapping of DSCP values to required queues, however on the interfaces where I am doing priority queueing (gig0/1 and gig0/2), no packets are matched in queue 0, although output shows alot of packets outbound with DSCP 46, which is mapped to queue 1 (0)....

but on interface gig0/3, it shows a good amount of packets in queue 0 - however only about half of the packets with DSCP 46 outgoing..

I have done MLS configure as shown in the below config snippets:

-------- config start --------------------------

mls qos map cos-dscp 0 8 16 24 32 46 48 56
mls qos srr-queue output cos-map queue 1 threshold 3 5
mls qos srr-queue output cos-map queue 2 threshold 3 3 6 7
mls qos srr-queue output cos-map queue 3 threshold 3 4
mls qos srr-queue output cos-map queue 4 threshold 3 0 1 2
mls qos srr-queue output dscp-map queue 1 threshold 3 46
mls qos srr-queue output dscp-map queue 2 threshold 3 24 48 56 58
mls qos srr-queue output dscp-map queue 3 threshold 3 16 34
mls qos srr-queue output dscp-map queue 4 threshold 2 8
mls qos srr-queue output dscp-map queue 4 threshold 3 0 1 2 3 4 5 6 7
mls qos srr-queue output dscp-map queue 4 threshold 3 9 10 11 12 13 14 15 17
mls qos srr-queue output dscp-map queue 4 threshold 3 18 19 20 21 22 23 25 26
mls qos srr-queue output dscp-map queue 4 threshold 3 27 28 29 30 31 32 33 35
mls qos srr-queue output dscp-map queue 4 threshold 3 36 37 38 39 40 41 42 43
mls qos srr-queue output dscp-map queue 4 threshold 3 44 45 47 49 50 51 52 53
mls qos srr-queue output dscp-map queue 4 threshold 3 54 55 57 59 60 61 62 63
mls qos

interface GigabitEthernet0/1
switchport access vlan 70
switchport mode access
srr-queue bandwidth shape 6 2 6 6
priority-queue out
mls qos trust dscp
!
interface GigabitEthernet0/2
switchport access vlan 80
switchport mode access
srr-queue bandwidth shape 7 20 7 7
priority-queue out
mls qos trust dscp
!
interface GigabitEthernet0/3
switchport access vlan 200
switchport mode access
mls qos vlan-based

interface Vlan70
ip address x.x.x.x 255.255.255.252
!
interface Vlan80
ip address y.y.y.y 255.255.255.0
!
interface Vlan200
ip address z.z.z. 255.255.255.0
service-policy input <Policymap used for marking>

---------------config end------------------------

-------------show mls qos interface statistics----------------------------------

GigabitEthernet0/1

dscp: incoming
-------------------------------

0 - 4 : 534 0 0 0 0
5 - 9 : 0 0 0 0 0
10 - 14 : 0 0 0 0 0
15 - 19 : 0 2062357 0 0 0
20 - 24 : 3574 0 0 0 1434436
25 - 29 : 0 0 0 0 0
30 - 34 : 0 0 0 0 0
35 - 39 : 0 0 0 0 0
40 - 44 : 0 0 0 0 0
45 - 49 : 0 30187521 0 39543 0
50 - 54 : 0 0 0 0 0
55 - 59 : 0 0 0 0 0
60 - 64 : 0 0 0 0
dscp: outgoing
-------------------------------

0 - 4 : 26012445 0 0 0 0
5 - 9 : 0 0 0 0 0
10 - 14 : 0 0 0 0 0
15 - 19 : 0 15 0 0 0
20 - 24 : 0 0 0 0 388717
25 - 29 : 0 0 0 0 0
30 - 34 : 0 0 0 0 0
35 - 39 : 0 0 0 0 0
40 - 44 : 0 0 0 0 0
45 - 49 : 0 7236546 0 74489 0
50 - 54 : 0 0 0 0 11107
55 - 59 : 0 0 0 0 0
60 - 64 : 0 0 0 0
cos: incoming
-------------------------------

0 - 4 : 33861629 0 0 0 0
5 - 7 : 0 0 0
cos: outgoing
-------------------------------

0 - 4 : 33821944 2 13 0 0
5 - 7 : 0 64394 571047
output queues enqueued:
queue: threshold1 threshold2 threshold3
-----------------------------------------------
queue 0: 0 0 0
queue 1: 0 179 961385
queue 2: 0 0 0
queue 3: 0 0 33648766

output queues dropped:
queue: threshold1 threshold2 threshold3
-----------------------------------------------
queue 0: 0 0 0
queue 1: 0 0 0
queue 2: 0 0 0
queue 3: 0 0 0

Policer: Inprofile: 0 OutofProfile: 0

GigabitEthernet0/2

dscp: incoming
-------------------------------

0 - 4 : 51769705 0 0 0 0
5 - 9 : 0 0 0 0 0
10 - 14 : 0 0 0 0 0
15 - 19 : 0 0 0 0 0
20 - 24 : 0 0 0 0 0
25 - 29 : 0 0 0 0 0
30 - 34 : 0 0 0 0 0
35 - 39 : 0 0 0 0 0
40 - 44 : 0 0 0 0 0
45 - 49 : 0 0 0 0 0
50 - 54 : 0 0 0 0 0
55 - 59 : 0 0 0 0 0
60 - 64 : 0 0 0 0
dscp: outgoing
-------------------------------

0 - 4 : 29636188 0 0 0 0
5 - 9 : 0 0 0 0 0
10 - 14 : 0 0 0 0 0
15 - 19 : 0 2041347 0 0 0
20 - 24 : 0 0 0 0 1284668
25 - 29 : 0 0 0 0 0
30 - 34 : 0 0 0 0 0
35 - 39 : 0 0 0 0 0
40 - 44 : 0 0 0 0 0
45 - 49 : 0 15103757 0 470547 0
50 - 54 : 0 0 0 0 0
55 - 59 : 0 0 0 0 0
60 - 64 : 0 0 0 0
cos: incoming
-------------------------------

0 - 4 : 51905812 0 0 0 0
5 - 7 : 0 0 0
cos: outgoing
-------------------------------

0 - 4 : 47000473 2 1350108 65 15
5 - 7 : 0 350621 571138
output queues enqueued:
queue: threshold1 threshold2 threshold3
-----------------------------------------------
queue 0: 0 0 0
queue 1: 0 1051 1180762
queue 2: 0 0 1350108
queue 3: 0 0 46740591

output queues dropped:
queue: threshold1 threshold2 threshold3
-----------------------------------------------
queue 0: 0 0 0
queue 1: 0 0 0
queue 2: 0 0 0
queue 3: 0 0 0

Policer: Inprofile: 0 OutofProfile: 0

GigabitEthernet0/3

dscp: incoming
-------------------------------

0 - 4 : 465945 0 0 0 2
5 - 9 : 0 0 0 0 0
10 - 14 : 0 0 0 0 0
15 - 19 : 0 7451 0 859 0
20 - 24 : 18896 0 0 0 5975928
25 - 29 : 0 17246 0 0 0
30 - 34 : 0 0 0 0 0
35 - 39 : 0 0 0 0 0
40 - 44 : 0 0 0 0 0
45 - 49 : 0 105681385 0 96582 0
50 - 54 : 0 0 0 0 57841
55 - 59 : 0 0 0 0 0
60 - 64 : 0 0 0 0
dscp: outgoing
-------------------------------

0 - 4 : 69548199 0 0 0 4
5 - 9 : 0 0 0 0 0
10 - 14 : 0 0 0 0 0
15 - 19 : 0 10 0 0 0
20 - 24 : 0 0 0 0 1738449
25 - 29 : 0 0 0 0 0
30 - 34 : 0 0 0 0 0
35 - 39 : 0 0 0 0 0
40 - 44 : 0 0 0 0 5639
45 - 49 : 0 40929946 0 20260 0
50 - 54 : 0 0 0 0 1662
55 - 59 : 0 0 0 0 0
60 - 64 : 0 0 0 0
cos: incoming
-------------------------------

0 - 4 : 112597489 0 0 0 0
5 - 7 : 0 0 0
cos: outgoing
-------------------------------

0 - 4 : 77581048 302544 10449 1015610 1
5 - 7 : 33701544 15316 570545
output queues enqueued:
queue: threshold1 threshold2 threshold3
-----------------------------------------------
queue 0: 0 0 22906346
queue 1: 0 686 1922225
queue 2: 0 0 0
queue 3: 0 0 88535635

output queues dropped:
queue: threshold1 threshold2 threshold3
-----------------------------------------------
queue 0: 0 0 0
queue 1: 0 0 0
queue 2: 0 0 0
queue 3: 0 0 0

Policer: Inprofile: 0 OutofProfile: 0

----------------------------------------------------------------------

Joseph W. Doherty · ‎12-19-2018

". . . (gig0/1 and gig0/2), no packets are matched in queue 0 . . ."

GigabitEthernet0/1

.
.
dscp: outgoing
.
.
45 - 49 : 0 7236546 0 74489 0
.
.

GigabitEthernet0/2

.
.
dscp: outgoing
.
.
45 - 49 : 0 15103757 0 470547 0
.
.

The stats show matches . . .

GigabitEthernet0/1

.
.
output queues enqueued:
queue: threshold1 threshold2 threshold3
-----------------------------------------------
queue 0: 0 0 0
queue 1: 0 179 961385
queue 2: 0 0 0
queue 3: 0 0 33648766

GigabitEthernet0/2

.
.
output queues enqueued:
queue: threshold1 threshold2 threshold3
-----------------------------------------------
queue 0: 0 0 0
queue 1: 0 1051 1180762
queue 2: 0 0 1350108
queue 3: 0 0 46740591

The stats show no packets enqueued in PQ, but that's not the same as no packets using PQ. I.e. no packets had to wait in the PQ.

rasmusan1 · ‎12-19-2018

Hi

Thanks for replying...... are you 100% sure about that? that the "output queues enqueued" statistics only shows packets queued...

Because in a lab I did, with similar config, the packets actually did show up under queue 0.... also when counting the packets in the "dscp: outgoing" chart, the number seems to get very close to the numbers of packets counted from all 4 queues in "output queues enqueued"....

Joseph W. Doherty · ‎12-19-2018

No, I'm not 100% sure, but if enqueued stats do count all packets directly to the queue, then the sum of packets in that queue should match the output counters (CoS and/or DSCP) do that hardware queue too. "Enqueued", should mean, but perhaps doesn't, packets that had to be queued.

(BTW, on ISRs, I found, at least on some IOS versions, CBWFQ queues only counted packets that overflowed the interface's hardware [tx] FIFO queue; not all packets that logically matched the CBWFQ class. I mention this, as something similar might be happening. I would expect your PQ traffic to be low volume, and if given absolute priority over other traffic, it shouldn't need to be queued.)

Further, my experience with the 3750 series (which likely also applies to the various corresponding 3560 peers) has been different IOS versions can be somewhat buggy, sometimes such bug have incorrect stats. Was your lab's similar config also on identical hardware with identical IOS version?

rasmusan1 · ‎12-20-2018

yes, I also suspect buggy behavior.... platform in my lab is not same hardware, and not same IOS version, so could very well be the case....

I think maybe I will create a TAC case to have this verified