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QoS issue on 3750

afredriksson
Level 1
Level 1
 
 

Hi all,

I have a QoS issue with a cisco 3750-stack (2 x WS-C3750-24TS, 12.2(53)SE).

We have some PBX- and Web systems connected via trunks to GE-ports and service providers (MPLS based IP-VPN) connected to FE-ports. Traffic rate on most ports are very low, approx. 1-3 Mbit/s.

One SP port connects many sites so that port tends to hover around 10Mbit/s, of which most traffic is VoIP using DSCP40/46. That port is now dropping traffic.

The QoS configuration is generated long ago using “Auto-Qos” and have worked fine for years, but now when one port tends to go above 10Mbit/s, VoIP packets gets dropped.

Short term solution is to turn off QoS (no mls qos) but that might open another box of problems...

Any suggestions on how to increase RTP flow (out Q1T3) and “allow” up to about 20% (20 Mbit/s) VoIP traffic on SP links?

 

QoS Config:

mls qos map cos-dscp 0 8 16 26 32 46 48 56

mls qos srr-queue input bandwidth 70 30

mls qos srr-queue input threshold 1 8 16

mls qos srr-queue input threshold 2 34 66

mls qos srr-queue input buffers 60 40

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

mls qos srr-queue input cos-map queue 1 threshold 3 0

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

mls qos srr-queue input cos-map queue 2 threshold 2 4 6 7

mls qos srr-queue input cos-map queue 2 threshold 3 3 5

mls qos srr-queue input dscp-map queue 1 threshold 2 9 10 11 12 13 14 15

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

mls qos srr-queue input dscp-map queue 1 threshold 3 32

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

mls qos srr-queue input dscp-map queue 2 threshold 2 33 34 35 36 37 38 39 48

mls qos srr-queue input dscp-map queue 2 threshold 2 49 50 51 52 53 54 55 56

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

mls qos srr-queue input dscp-map queue 2 threshold 3 24 25 26 27 28 29 30 31

mls qos srr-queue input dscp-map queue 2 threshold 3 40 41 42 43 44 45 46 47

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 2 4

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

mls qos srr-queue output cos-map queue 4 threshold 3 0

mls qos srr-queue output dscp-map queue 1 threshold 3 40 41 42 43 44 45 46 47

mls qos srr-queue output dscp-map queue 2 threshold 3 24 25 26 27 28 29 30 31

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 16 17 18 19 20 21 22 23

mls qos srr-queue output dscp-map queue 3 threshold 3 32 33 34 35 36 37 38 39

mls qos srr-queue output dscp-map queue 4 threshold 1 8

mls qos srr-queue output dscp-map queue 4 threshold 2 9 10 11 12 13 14 15

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

mls qos queue-set output 1 threshold 1 138 138 92 138

mls qos queue-set output 1 threshold 2 138 138 92 400

mls qos queue-set output 1 threshold 3 36 77 100 318

mls qos queue-set output 1 threshold 4 20 50 67 400

mls qos queue-set output 2 threshold 1 149 149 100 149

mls qos queue-set output 2 threshold 2 118 118 100 235

mls qos queue-set output 2 threshold 3 41 68 100 272

mls qos queue-set output 2 threshold 4 42 72 100 242

mls qos queue-set output 1 buffers 10 10 26 54

mls qos queue-set output 2 buffers 40 10 20 30

 

 

SP Interface config:

interface FastEthernet1/0/19

 description xxx

 switchport trunk encapsulation dot1q

 switchport trunk native vlan x

 switchport trunk allowed vlan x,x,x

 switchport mode trunk

 srr-queue bandwidth share 10 10 60 20

 mls qos trust dscp

 spanning-tree portfast

 

I have tried using:

srr-queue bandwidth share 30 10 20 40

queue-set 2

Result: Worse (Tried with and without queue-set 2)

 

 

sh mls qos int fa 1/0/19 statistics:

FastEthernet1/0/19 (All statistics are in packets)

 

  dscp: incoming

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

 

  0 -  4 :     3460743            0            0            0            0

  5 -  9 :           0            0            0       181282            0

 10 - 14 :           0            0            0            0            0

 15 - 19 :           0            0            0            0            0

 20 - 24 :           0            0            0            0       134758

 25 - 29 :           0           99            0            0            0

 30 - 34 :           0            0            0            0         8227

 35 - 39 :           0            0            0            0            0

 40 - 44 :     6835905            0            0            0            0

 45 - 49 :           0       436411            0        16060            0

 50 - 54 :           0            0            0            0            0

 55 - 59 :           0         1653            0            0            0

 60 - 64 :           0            0            0            0

  dscp: outgoing

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

 

  0 -  4 :      204275            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       177984

 25 - 29 :           0            0            0            0            0

 30 - 34 :           0            0            0            0        20758

 35 - 39 :           0            0            0            0            0

 40 - 44 :     9603319            0            0            0            0

 45 - 49 :           0       617236            0         2257            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 :    11078474            0            0            0            0

  5 -  7 :           0            0            0

  cos: outgoing

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

 

  0 -  4 :    10431109            0            0         8766          613

  5 -  7 :      183165         2176            0

  output queues enqueued:

 queue:    threshold1   threshold2   threshold3

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

 queue 0:           0           0      183165

 queue 1:           0        4619       11357

 queue 2:           0           0         613

 queue 3:           0           0    10434914

 

  output queues dropped:

 queue:    threshold1   threshold2   threshold3

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

 queue 0:           0           0      113326

 queue 1:           0           0           0

 queue 2:           0           0           0

 queue 3:           0           0           0

 

Policer: Inprofile:            0 OutofProfile:            0

 

Regards,

Anders

 
 
1 Accepted Solution

Accepted Solutions

acampbell
VIP Alumni
VIP Alumni

Hi Anders,

A very important command is missing from your interface when you use QOS.

!
Int fas 1/0/19
priority-queue out
!


All four queues participate in the SRR unless the priority queue is enabled, in which case the first bandwidth weight is ignored and is not used in the ratio calculation. Priority queue is serviced until empty before the other queues are serviced. You enable the priority queue by using the priority-queue out interface configuration command.

Regards
Alex

Regards, Alex. Please rate useful posts.

View solution in original post

1 Reply 1

acampbell
VIP Alumni
VIP Alumni

Hi Anders,

A very important command is missing from your interface when you use QOS.

!
Int fas 1/0/19
priority-queue out
!


All four queues participate in the SRR unless the priority queue is enabled, in which case the first bandwidth weight is ignored and is not used in the ratio calculation. Priority queue is serviced until empty before the other queues are serviced. You enable the priority queue by using the priority-queue out interface configuration command.

Regards
Alex

Regards, Alex. Please rate useful posts.
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