[cisco-voip] One-way Voice Issues

Wed Sep 12 02:34:37 EDT 2007

When you have issues across the pstn interfaces like ISDN PRIs you
alos need to look at the following:

The clocking 

========== verify by doing this

sh network-clocks 

  Network Clock Configuration 

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

  Priority      Clock Source    Clock State     Clock Type 

     1          E1 0/0/0        GOOD            E1          

    11          Backplane       GOOD            PLL         

  Current Primary Clock Source 

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

  Priority      Clock Source    Clock State     Clock Type 

     1          E1 0/0/0        GOOD            E1          \\\

To configure the clocking on the voice gateway look at a doc called:

Clocking Configurations On Voice-Capable IOS-Based Platforms

On a 2800 it would be something like below:

!

card type e1 0 0

network-clock-participate wic 0 

network-clock-select 1 E1 0/0/0

network-clock-select 2 E1 0/0/1

!

isdn switch-type primary-net5

!

controller E1 0/0/0

 pri-group timeslots 1-31

can also look at the info below

K58400523

Title

User experiences no audio or one-way audio on IP phones when calls are
placed across 2691 or 3700 gateways

Core Issue

No audio or one-way audio is experienced, even though the show call
active voice
<http://www.cisco.com/cgi-bin/Support/Cmdlookup/ios-command-lookup.pl?
type=reference&query=show+call+active+voice+&paging=25&counter=0&relea
se=123&su=Submit>  and show voice dsp
<http://www.cisco.com/cgi-bin/Support/Cmdlookup/ios-command-lookup.pl?
type=reference&query=show+voice+dsp+&paging=25&counter=0&release=123&s
a=Submit>  commands issued at the gateway indicate that packets are
transmitted and received. 

The most obvious symptom is the repeating clock slips on the E1 or T1
interface. The show controller command shows the repeating clock
slips, as shown in the following example:

Router#show controller e1 0/0

 E1 0/0 is up.

  Applique type is Channelized E1 - balanced

  No alarms detected.

  alarm-trigger is not set

  Version info Firmware: 20020812, FPGA: 11

  Framing is CRC4, Line Code is HDB3, Clock Source is Line.

  Data in current interval (97 seconds elapsed):

     0 Line Code Violations, 0 Path Code Violations

     4 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

     4 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail
Secs

  Total Data (last 14 15 minute intervals):

     1 Line Code Violations, 4 Path Code Violations,

     425 Slip Secs, 0 Fr Loss Secs, 1 Line Err Secs, 0 Degraded Mins,

     427 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0
Unavail Secs

The digital errors cause the fax machines to misinterpret the digital
signal, and training is unsuccessful.

The Digital Signal Processor (DSP) resources of the Advanced
Integration Module (AIM) on a Cisco 2600 and 3700 are accessed through
Time-Division Multiplexing (TDM) based architecture. Clocking errors
occur as a result of the AIM module not being clocked from the
appropriate digital line. 

Note: The default clocking configuration is for the AIM module to
source clock from the router backplane. On the other hand, the digital
interface defaults to clocking from the line. In situations such as
these, where digital interfaces need to source clock across the TDM
backplane, its default clocking mode needs to be changed.

Resolution

To resolve the issue, perform these steps: 

1.	Ensure that the clock source line
<http://www.cisco.com/cgi-bin/Support/Cmdlookup/ios-command-lookup.pl?
type=reference&query=clock+source+line+&paging=25&counter=0&release=12
3&su=Submit>  command is issued under the appropriate controller. The
Voice and WAN Interface Card (VWIC) controller configuration defaults
to clock source line. However, the recovered clock is not used to
drive the AIM module. Therefore, this configuration is not sufficient
to resolve the clock slip problem. 
2.	To allow the router to recover the clock from the E1/T1 VWIC
and pass it across the backplane to the AIM, the
network-clock-participate
<http://www.cisco.com/cgi-bin/Support/Cmdlookup/ios-command-lookup.pl?
type=reference&query=network-clock-participate+&paging=25&counter=0&re
lease=123&sa=Submit>  command is added in global configuration mode.
If multiple VWICS are installed, the command is appropriately
repeated. 
3.	To allow the AIM modules in a 3700 or 2691 to participate in
the system clocking, the network-clock-participate command is added
for each AIM module. 
4.	Specify the network clock source and priority. Issue the
network-clock-select
<http://www.cisco.com/cgi-bin/Support/Cmdlookup/ios-command-lookup.pl?
type=reference&query=network-clock-select&paging=25&counter=0&release=
123&sa=Submit>  command in global configuration mode. 

This is an example of the required configuration:

Router#conf t            

Enter configuration commands, one per line.  End with CNTL/Z.

Router(config)#network-clock-participate wic 0

Router(config)#network-clock-participate aim 0    

Router(config)#network-clock-select 1 t1 0/0    

Router(config)#^Z

Issue the show network-clocks
<http://www.cisco.com/cgi-bin/Support/Cmdlookup/ios-command-lookup.pl?
type=reference&query=show+network-clocks+&paging=25&counter=0&release=
123&sa=Submit>  command to confirm the system clocking, as shown in
this example:

Router#show network-clocks 

  Network Clock Configuration 

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

  Priority      Clock Source    Clock State     Clock Type 

    0             T1 0/0             Good               T1  

    5          Backplane             Good               PLL 

  Current Primary Clock Source 

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

  Priority      Clock Source    Clock State     Clock Type 

     0             T1 0/0            Good               T1   

For more information on synchronized clocking, refer to the NAS
Clocking Commands
<http://www.cisco.com/en/US/customer/tech/tk713/tk628/technologies_tec
h_note09186a008014f8a6.shtml#topic8>  section of Clock Synchronization
for AS5xxx Network Access Servers
<http://www.cisco.com/en/US/customer/tech/tk713/tk628/technologies_tec
h_note09186a008014f8a6.shtml> .

For more background information on clocking configurations, refer to
Clocking Configurations On Voice-Capable IOS-Based Platforms
<http://www.cisco.com/en/US/customer/products/hw/routers/ps259/product
s_tech_note09186a008031a072.shtml> 

________________________________

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Ted Nugent
Sent: Wednesday, September 12, 2007 1:59 AM
To: Weigand, John V.
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] One-way Voice Issues

Some points to note.

You're really not experiencing a 1 way audio issue. 1 way audio is
typically when the return audio stream is lost in one direction
entirely via a routing issue or similar and you have no audio (dead
air) in one direction. You are however running in a voice quality
issue that can be a pain in the ass to track down. I've run into very
similar issues a few times in the past and it has always turned out to
be one of 3 issues. I'll assume that these are all external calls to
or from the PSTN that are being affected, I can't invision this
occurring on an internal call unless this audio stream was hitting a
WAN or VPN link in which case it could be a QOS issue (or lack of
QOS). 

1: Bad DSPs on the Voice gateway which explains the intermittent
problem if its only one or a part of a DSP that's bad and is only hit
intermittently 

2: Buggy code on the IOS gateway, there were some really ugly DSP type
bugs in previous code that could be causing this. 

3: PRI issue/provider issue, low signal or similar on the PRI

Out of the 3 I'd be leaning towards bad DSPs but any of the 3 will
likely require a TAC case.

On 9/11/07, Weigand, John V. <jvw at medicineforthedefense.com> wrote: 

Litigation Management

Serious Medicine for the Defense (r)
<http://www.medicineforthedefense.com/> 

Our CCM5.x system was installed by our vendor back in February. Since
then, we've had an ongoing one way voice issue. Every so often (mostly
reported by our phone receptionists, but by a few other key users),
they'll either receive or make a call, and be nearly unable to hear
the person on the other end. They can just barely make out their
voice, and adjusting the phone volume does nothing. The person on the
other end is able to hear them with no issue. 

We've tried swapping the phones, etc, with no luck. I've had no formal
Callmanager or even VOIP training, but I've been able to pick up a
lot, and administration of the system has fallen to me. I found this
document
<http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note091
86a008009484b.shtml>  about troubleshooting voice issues, and (based
on my very limited knowledge), I'm wondering if it has something to do
with Media Termination Points. Based on what I've read, there's a
difference between configuring those on CCM4 and CCM5, and our vendor
really knew nothing about CCM5, and set it up as if it was CCM4. 

Can anyone give me some guidance on how I can learn more about
this/figure it out/any other possible ideas what could be causing it?

Thanks so much!

John V. Weigand
Help Desk Support

Litigation Management Inc. 
300 Allen-Bradley Drive 
Suite 200
Mayfield Heights, OH 44124

Tel: 
Fax: 440-484-2020
Cell: 
email: <mailto:jvw at medicineforthedefense.com>
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<mailto:jvw at medicineforthedefense.com> jvw at medicineforthedefense.com 

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