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We have been experiencing an issue with one-way VOIP calls from our Cisco 7936 conference phone, as of late.

Initially, the call starts off OK, but after few minutes remote leg drops and they cannot hear us. This applies to internal and external calls.

Phone - Cisco 7936

Protocols

CUCM 9.1

VG - 2921 IOS 15

Phone is connected to 2960P 10/100mbps switch

On the interface it connects to I can see multiple drops

Can we improve our QOS settings at all? If so, what bits need changing?

Should I disable QOS globally on the switch to see if QOS is at fault?

Some show output from the 2960P switch

FROM INTERFACE

sh mls qos int fa 0/33 statistics
FastEthernet0/33 (All statistics are in packets)
dscp: incoming
-------------------------------
0 - 4 : 108722 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 2833166
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 28807936 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 : 407407368 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 480949  
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 756928 0 5353 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 : 602511 0 0 2832957 0  
5 - 7 : 28807936 0 0  
cos: outgoing  
-------------------------------  
0 - 4 : 1372914286 0 0 1495358 0  
5 - 7 : 1021323 5353 11171  
Policer: Inprofile: 8845 OutofProfile: 0
sh int fa 0/33 switching

FastEthernet0/33
Throttle count 0
Drops RP 0 SP 0
SPD Flushes Fast 0 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 0 Drops 0
Protocol Path Pkts In Chars In Pkts Out Chars Out
Other Process 0 0 2695252 161715120
Cache misses 0
Fast 0 0 0 0
Auton/SSE 0 0 0 0
Spanning Tree Process 0 0 26729009 1710656576
Cache misses 0
Fast 0 0 0 0
Auton/SSE 0 0 0 0
CDP Process 449615 65194111 449590 295830220
Cache misses 0
Fast 0 0 0 0
Auton/SSE 0 0 0 0
Policed-dscp map:
d1 : d2 0 1 2 3 4 5 6 7 8 9
---------------------------------------
0 : 00 01 02 03 04 05 06 07 08 09
1 : 10 11 12 13 14 15 16 17 18 19
2 : 20 21 22 23 00 25 00 27 28 29
3 : 30 31 32 33 34 35 36 37 38 39
4 : 40 41 42 43 44 45 00 47 48 49
5 : 50 51 52 53 54 55 56 57 58 59
6 : 60 61 62 63
Dscp-cos map:
d1 : d2 0 1 2 3 4 5 6 7 8 9
---------------------------------------
0 : 00 00 00 00 00 00 00 00 01 01
1 : 01 01 01 01 01 01 02 02 02 02
2 : 02 02 02 02 03 03 03 03 03 03
3 : 03 03 04 04 04 04 04 04 04 04
4 : 05 05 05 05 05 05 05 05 06 06
5 : 06 06 06 06 06 06 07 07 07 07
6 : 07 07 07 07
Cos-dscp map:
cos: 0 1 2 3 4 5 6 7
--------------------------------
dscp: 0 8 16 24 32 46 48 56
#show platform port-asic stats drop

Port-asic Port Drop Statistics - Summary
========================================
RxQueue 0 Drop Stats: 0
RxQueue 1 Drop Stats: 0
RxQueue 2 Drop Stats: 0
RxQueue 3 Drop Stats: 0
Port 0 TxQueue Drop Stats: 0
Port 1 TxQueue Drop Stats: 0
Port 2 TxQueue Drop Stats: 440662713
Port 3 TxQueue Drop Stats: 440672169
Port 4 TxQueue Drop Stats: 440661375
Port 5 TxQueue Drop Stats: 440683372
Port 6 TxQueue Drop Stats: 440659135
Port 7 TxQueue Drop Stats: 440706463
Port 8 TxQueue Drop Stats: 101014
Port 9 TxQueue Drop Stats: 440664511
Port 10 TxQueue Drop Stats: 440672995
Port 11 TxQueue Drop Stats: 441258960
Port 12 TxQueue Drop Stats: 440659986
Port 13 TxQueue Drop Stats: 440652146
Port 14 TxQueue Drop Stats: 1406763
Port 15 TxQueue Drop Stats: 440658062
Port 16 TxQueue Drop Stats: 440655907
Port 17 TxQueue Drop Stats: 440677503
Port 18 TxQueue Drop Stats: 440651635
Port 19 TxQueue Drop Stats: 440661862
Port 20 TxQueue Drop Stats: 440660011
Port 21 TxQueue Drop Stats: 442472877
Port 22 TxQueue Drop Stats: 133670
Port 23 TxQueue Drop Stats: 440664683
Port 24 TxQueue Drop Stats: 440661050
Port 25 TxQueue Drop Stats: 440659656
Supervisor TxQueue Drop Statistics
Queue 0: 0
Queue 1: 0
Queue 2: 0
Queue 3: 1239773644
Queue 4: 0
Queue 5: 0
Queue 6: 0
Queue 7: 15220
Queue 8: 1302109834
Queue 9: 0
Queue 10: 62354137
Queue 11: 0
Queue 12: 0
Queue 13: 0
Queue 14: 0
Queue 15: 0

EDIT - EXTRA SHOW OUTPUT

**#sh mls qos** 
QoS is enabled
QoS ip packet dscp rewrite is enabled


**#show mls qos interface fa0/23**

FastEthernet0/23
Attached policy-map for Ingress: AutoQoS-Police-CiscoPhone
trust state: trust cos
trust mode: trust cos
trust enabled flag: ena
COS override: dis
default COS: 0
DSCP Mutation Map: Default DSCP Mutation Map
Trust device: cisco-phone
qos mode: port-based
MK-2960P-01#show mls qos interface fa0/33
FastEthernet0/33
Attached policy-map for Ingress: AutoQoS-Police-CiscoPhone
trust state: trust cos
trust mode: trust cos
trust enabled flag: ena
COS override: dis
default COS: 0
DSCP Mutation Map: Default DSCP Mutation Map
Trust device: cisco-phone
qos mode: port-based

**#sh run int fa0/33**

Building configuration...
Current configuration : 324 bytes
!
interface FastEthernet0/33
 switchport access vlan 20
 switchport mode access
 switchport voice vlan 50
 srr-queue bandwidth share 10 10 60 20
 priority-queue out 
 mls qos trust device cisco-phone
 mls qos trust cos
 auto qos voip cisco-phone 
 spanning-tree portfast
 service-policy input AutoQoS-Police-CiscoPhone
end


**#show mls qos queue-set**

Queueset: 1
Queue     :       1       2       3       4
----------------------------------------------
buffers   :      10      10      26      54
threshold1:     138     138      36      20
threshold2:     138     138      77      50
reserved  :      92      92     100      67
maximum   :     138     400     318     400
Queueset: 2
Queue     :       1       2       3       4
----------------------------------------------
buffers   :      16       6      17      61
threshold1:     149     118      41      42
threshold2:     149     118      68      72
reserved  :     100     100     100     100
maximum   :     149     235     272     242


**#show platform port-asic stats drop FastEthernet 0/33**
  Interface Fa0/33 TxQueue Drop Statistics
    Queue 0
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 1
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 2
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 0
    Queue 3
      Weight 0 Frames 0
      Weight 1 Frames 0
      Weight 2 Frames 451146373

**#sh int fa0/33 capabilities**
FastEthernet0/33
  Model:                 WS-C2960-48PST-L
  Type:                  10/100BaseTX
  Speed:                 10,100,auto
  Duplex:                half,full,auto
  Trunk encap. type:     802.1Q
  Trunk mode:            on,off,desirable,nonegotiate
  Channel:               yes
  Broadcast suppression: percentage(0-100)
  Flowcontrol:           rx-(off,on,desired),tx-(none)
  Fast Start:            yes
  QoS scheduling:        rx-(not configurable on per port basis),
                         tx-(4q3t) (3t: Two configurable values and one fixed.)
  CoS rewrite:           yes
  ToS rewrite:           yes
  UDLD:                  yes
  Inline power:          yes
  SPAN:                  source/destination
  PortSecure:            yes
  Dot1x:                 yes


**#show mls qos interface fastEthernet 0/33 queueing**
FastEthernet0/33
Egress Priority Queue : enabled
Shaped queue weights (absolute) :  25 0 0 0
Shared queue weights  :  10 10 60 20
The port bandwidth limit : 100  (Operational Bandwidth:100.0)
The port is mapped to qset : 1
Improve this question
3
  • Can you please provide following: "sh mls qos" "show mls qos interface fa0/23" "sh run int fa0/23" "show mls qos queue-set" "show platform port-asic stats drop FastEthernet 0/23" "sh int fa0/23 capabilities" "show mls qos interface fastEthernet 0/23 queuing" You can try disabling flow control as a first step.
    – Viktor Borisov
    Dec 15, 2016 at 9:26
  • It's a codec issue.
    – Ronnie Royston
    Feb 13, 2017 at 19:04
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin ♦
    Aug 12, 2017 at 22:45

2 Answers 2

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2

@Dan I do not have reputation required, so I can't add comments... Please excuse me. Regarding the issue as far as I can see you have egress drops on queue 3 only.

Here you are a guide describing very precisely how to configure the egress profile (QoS in 2960 is the same as 3750):

Catalyst QOS config

When SRR scheduler is configured in shared mode, bandwidth allocated to each queue is based on relative weight. E.g. when configuring “srr-queue bandwidth share 30 20 25 25″ we obtain the weight sum as 30+20+25+25 = 100 (could be different, but it’s nice to reference to “100”, as a representation of 100%). Relative weights are therefore “30/100”, “20/100”, “25/100”, “25/100” and you can calculate the effective bandwidth guaranteed to a queue multiplying this weight by the interface bandwidth: e.g. 30/100*100Mbps = 30Mbps for the 100Mbps interface and 30/100*10Mbps=3Mbps for 10Mbps interface. Of course, the weights are only taken in consideration when interface is oversubscribed, i.e. experiences a congestion.

When you enable “priority-queue out” on an interface, it turns queue 1 into priority queue, and scheduler effectively does not account for the queue’s weight in calculations. Note that PQ will also ignore shaped mode settings as well, and this may make other queues starve. In my opinion you can try to remove it.

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0

An IP-based voice call requires 2 connections - establishment/control as well as payload/voice. Once the call is established, your conference phone is sending voice/media packets directly to the PSTN gateway (and gw to phone).

This is probably a routing or a resource (codec/capacity) issue.

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