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New Member

QOS Issue causing Telepresence video quality.

Hi,

I'm facing issue with QoS which is causing TP Video Quality degradation.

TelePresence is connected to L3 Switch (C3560G) where I've trusted dscp in the interface and for the uplink connecting to 6500 L2 switch I've configured trust COS. There is only cos-dscp mapping in my L3 switch and no dscp-cos mapping. Will this cause any issue while sending the packet to L2 switch,as I'm trusting COS in the L2 switch interface.

Moreover in TP, I'm seeing voice/video traffic marked as Best Effort and I've no option to change this in TP. Is this due to QoS configuration issue in the switch.

Everyone's tags (3)
12 REPLIES
Cisco Employee

QOS Issue causing Telepresence video quality.

Hi,

Are you seeing TP packets been remarked? Can you trust DSCP on all switches? Trust COS could protential break the DSCP value, because COS 5 maps to dscp 40 by default. You can change the default setting, but you could also just trust DSCP.

HTH,

Lei Tian

New Member

QOS Issue causing Telepresence video quality.

Can I do trust DSCP in 6k Catalyst L2 switch

Cisco Employee

QOS Issue causing Telepresence video quality.

Yes, you can trust DSCP on Cat6k L2 switch. It will use the incoming DSCP value for internal DSCP value, if the line card uses cos to queue map, it will use the DSCP to COS map to determine the egress queue.

The following document is very good for QoS on 6500.

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/white_paper_c11_538840.html

HTH,

Lei Tian

New Member

QOS Issue causing Telepresence video quality.

Hi,

But when I check the QoS statistics in the interface connected to TP, input is showing DSCP marked traffic, but output is showing DSCP 0. Is this causing the TP to take BE marking??

And for the uplink, I'm seeing classified traffic in input and output.

C3560G-24PS-01#sh mls qos interface g0/1 statistics

GigabitEthernet0/1

  dscp: incoming

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

  0 -  4 :    50551521            0            0            0         2763

  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     11238456

25 - 29 :           0            0            0            0            0

30 - 34 :           0            0            0            0   1952380679

35 - 39 :           0            0            0            0            0

40 - 44 :           0            0            0            0            0

45 - 49 :           0       888132            0        11750            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 :  2154167344            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            6            0            0            0

60 - 64 :           0            0            0            0

  cos: incoming

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

  0 -  4 :    63546934            0            0      2024775   1952380679

  5 -  7 :      833252            0            0

  cos: outgoing

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

  0 -  4 :  3006653445            0            0            0            0

  5 -  7 :     2547879            0            0

Policer: Inprofile:            0 OutofProfile:            0

-------------------------------------------Uplink--------------------------------------

C3560G-24PS-01#sh mls qos interface g0/25 statistics

GigabitEthernet0/25

  dscp: incoming

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

  0 -  4 :  1750957418            0            0            0            2

  5 -  9 :           0            0            0           15            0

10 - 14 :           0            0            0            0            0

15 - 19 :           0            0            0            0            0

20 - 24 :           0            0            0            0     21608274

25 - 29 :           0      1569363            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      7515571            0    580817471            0

50 - 54 :           0            0            0            0            0

55 - 59 :           0           10            0            0            0

60 - 64 :           0            0            0            0

  dscp: outgoing

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

  0 -  4 :  3977529209            0            0            0         2763

  5 -  9 :           0            0            0            0            0

10 - 14 :           0            0            0            0            0

15 - 19 :           0            2            0            0            0

20 - 24 :           0            0            0            0     11236432

25 - 29 :           0     34575004            0            0            0

30 - 34 :           0            0            0            0   1952380679

35 - 39 :           0            0            0            0            0

40 - 44 :           0            0            0            0            0

45 - 49 :           0     45515260            0        21055            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 :  3397982841           15            0     23116921            0

  5 -  7 :     7515489    438424644            0

  cos: outgoing

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

  0 -  4 :  3996821898            0        75291     45811453   1952380679

  5 -  7 :    46425936        21055        51948

Policer: Inprofile:            0 OutofProfile:            0

Cisco Employee

QOS Issue causing Telepresence video quality.

What DSCP value that TP uses? Can you confirmed it is marked before entering the switch? Can you share the configure for interface g0/1 and g0/25?

HTH,

Lei Tian

New Member

QOS Issue causing Telepresence video quality.

TP uses EF for voice and AF4 for video by default and there is no option to edit it. I suspect that since the ouput to TP from g0/1 is DSCP 0, TP is taking it as BE.

Below are the config.

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

C3560G-24PS-01#sh run int g0/1

interface GigabitEthernet0/1

description : Telepresence Room

switchport voice vlan 180

srr-queue bandwidth share 1 30 35 5

priority-queue out

mls qos trust dscp

spanning-tree portfast

end

C3560G-24PS-01#sh run int g0/25

interface GigabitEthernet0/25

description Link to Cat6500_L2switch port 5/8.

switchport trunk encapsulation dot1q

switchport mode trunk

srr-queue bandwidth share 10 10 60 20

srr-queue bandwidth shape  10  0  0  0

queue-set 2

priority-queue out

mls qos trust cos

auto qos voip trust

spanning-tree guard loop

spanning-tree cost 500

end

Cisco Employee

QOS Issue causing Telepresence video quality.

This may not be remarked by 3560. Clear the statics and run a test TP call, see if you see packet increase in the correct DSCP value on g0/1 incoming, and g0/25 outgoing direction.

HTH,

Lei Tian

New Member

QOS Issue causing Telepresence video quality.

Will this cause any impact for other traffic? I've many IP Phones connecting through same uplink..

New Member

QOS Issue causing Telepresence video quality.

Just now I had a check on the switch interface connecting Router where there is no trust configured.  Should I configure trust COS or DSCP here.

Cat6500_L2switch> sh port qos 7/8

QoS is enabled for the switch.

QoS policy source for the switch set to local.

Port  Interface Type Interface Type Policy Source Policy Source

      config         runtime        config        runtime

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

7/8      port-based     port-based          COPS         local

Port  TxPort Type  RxPort Type  Trust Type   Trust Type    Def CoS Def CoS

                                config       runtime       config  runtime

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

7/8        1p3q1t       1p1q0t    untrusted    untrusted        0       0

Port  Ext-Trust Ext-Cos

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

7/8  untrusted       0

(*)Runtime trust type set to untrusted.

Cisco Employee

QOS Issue causing Telepresence video quality.

No, the test will not impact your applicaiton. Yes, QoS needs to configured end to end. You need to have trust dscp on the interface connecting Router.

HTH,

Lei Tian

New Member

QOS Issue causing Telepresence video quality.

So, will trusting QoS cause any outage..??

Cisco Employee

QOS Issue causing Telepresence video quality.

No, I dont expect any outage of chaning interface qos trust level.

HTH,

Lei Tian

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