[cisco-voip] Dialogic SR140 T38 fax to 2921 vg problems

[Nick Matthews]

While not as common as slips, there are still many cases where the
carrier has interference within their network and it can cause similar
problems to this.  This is the next step after verifying that your LAN
and local controller are not causing the problems.

If you have a voice gateway, 'show call active voice brief' and 'show
call active fax brief' will help determine if you have LAN issues. The
lost x/x/x field shows lost/jitter/jitter (two types of jitter, the
difference is not relevant).  If you've got more than 1 or 2 packets
here, you may have a problem.


-nick


On Thu, May 6, 2010 at 9:07 AM, Dennis Heim <Dennis.Heim at cdw.com> wrote:
> Can you put an IP phone on the same segment/switch and place and outbound call and then hit the question-mark twice and see what your jitter, latency and dropped packets look like. Redundancy may help, or it may just help cover up a network/QOS issue that will rear its ugly head down the road.
>
> Dennis Heim
> Network Voice Engineer
> CDW  Advanced Technology Services
> 11711 N. Meridian Street, Suite 225
> Carmel, IN  46032
>
> 317.569.4255 Office
> 317.569.4201 Fax
> 317.694.6070 Cell
> dennis.heim at cdw.com
> www.berbee.com
>
> -----Original Message-----
> From: cisco-voip-bounces at puck.nether.net [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Carter, Bill
> Sent: Thursday, May 06, 2010 9:01 AM
> To: Jason Aarons (US)
> Cc: Cisco-Voip-Puck
> Subject: Re: [cisco-voip] Dialogic SR140 T38 fax to 2921 vg problems
>
> Wireshark capture shows a bad/corrupted packet from the gateway when they fail.
>
> No clock slips at all.
>
> I will try turning on redundancy.
>
> The fax server is GFI Faxmaker.
>
> Sent from my iPhone
>
> On May 6, 2010, at 7:05 AM, "Jason Aarons (US)" <jason.aarons at us.didata.com  > wrote:
>
>> On the SR140 I would install Wireshark and watch the H.323/T.30
>> exchange try to see what happens when it fails. Also what does
>> Captaris Enterprise Fax Manager show on that Channel?
>>
>> You could also enable T.38 packet redundancy on both sides.
>>
>> Are you having any clocking/slips on the PRI side?  show network-
>> clock, show controller t1
>>
>> ________________________________________
>> From: cisco-voip-bounces at puck.nether.net [cisco-voip-
>> bounces at puck.nether.net] On Behalf Of Carter, Bill
>> [bcarter at sentinel.com]
>> Sent: Wednesday, May 05, 2010 8:37 PM
>> To: Cisco-Voip-Puck
>> Subject: Re: [cisco-voip] Dialogic SR140 T38 fax to 2921 vg problems
>>
>> Sorry about that. accidentally hit send. I'll start over.
>>
>> We have a fax server using the Dialogic SR140 software for fax over
>> IP.  The fax server is local to the voice gateway.
>>
>> About 100 outbound faxes are sent 2x a day.
>>
>> The gateway is a Cisco 2921 GSR2 with IOS 15.0(1)M2.  PSTN is PRI
>>
>> The gateway is configured with:
>> voice service voip
>> fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback none !
>> dial-peer voice 1 voip
>> ...
>> fax-relay sg3-to-g3
>> fax nsf 000000
>> !
>> dial-peer voice 100 pots
>> preference 1
>> destination-pattern 81[2-9]..[2-9]......
>> incoming called-number .
>> direct-inward-dial
>> port 0/0/1:23
>> forward-digits 11
>>
>> When voip dial-peers are configured with:
>> no fax-relay ECM disable
>>
>> 75% off outbound faxes fail. the 25% that succeed have very
>> distorted/illegible pages. The test fax is a single page with every
>> line repeating the word "test". These successful faxes have distorted
>> text across the top 1/4 of the page.
>>
>> When fax-relay ECM is enabled and fax rate is set to 9600, outbound
>> success rates improve marginally. Text on the successful fax fills
>> 100% of the page with zero distortion.
>>
>> Any ideas?
>>
>> ~*~*~*~*~*~*~*~*~*~*
>> Bill Carter
>> Senior Business Communications Analyst CCIE 5022 Sentinel Technologies
>> SNR 217.391.5015
>> ~*~*~*~*~*~*~*~*~*~*
>>
>>
>>
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