asterisk users - Aug 2005 - How to fix a Blue Alarm?? Line Noise?

We are having line noise issues in our Asterisk to legacy PBX integration.
All SIP calls originating from IP phones sound crystal clear. All calls that
originate from the legacy PBX (Isoetec 228) and route through the Asterisk
and out SIP have a lot of line noise.

I believe I have it pinned down to these Blue Alarm errors that I can see on
the legacy PBX side. zttool shows no alarm but when I view the T1 stats on
the Isoetec I see numerous Blue Alarms.

The TE110P card in the Asterisk server is set as the sync source:

span=1,1,0,d4,ami
e&m=1-24

Our Isoetec tech says that the T1 card in our 228 does not provide timing so
I made the TE110P the sync source.

What are these Blue Alarm errors indicative of? I found some info on the
list but it didn't make much sense to me. Are there additional timing
parameters I can put in zaptel.conf/zapata.conf to fix this?

Thanks!


EVERYTHING BELOW HERE IS INFORMATIVE:

Just incase someone comes along the archive to find solutions for "Line
Noise" I have added this info as I made several adjustments to get the
results of zttest to a 99.99% accuracy.

1) No IRQ sharing
2) Turn *off* hyperthreading
3) Turn off unnecessary settings in BIOS: usb, LPT, serial
4) Turn off "ACPI power management" and the "APIC interrupt
controller" in
the kernel.

	acpi=off noapic <-- add these as kernel arguments

These changes brought my average from 99.85 to 99.99

Geoff Manning wrote:
> The TE110P card in the Asterisk server is set as the sync source:
> 
> span=1,1,0,d4,ami
> e&m=1-24
That is incorrect. You have your span configured to recover timing from 
the T1 and use that as the source for the card. If you want this span to 
be clocked using the onboard clock on the board, you must use:

span=1,0,0,d4,ami

On Thu, 11 Aug 2005, Geoff Manning wrote:
> We are having line noise issues in our Asterisk to legacy PBX integration.
> All SIP calls originating from IP phones sound crystal clear. All calls
that
> originate from the legacy PBX (Isoetec 228) and route through the Asterisk
> and out SIP have a lot of line noise.
> 
> I believe I have it pinned down to these Blue Alarm errors that I can see
on
> the legacy PBX side. zttool shows no alarm but when I view the T1 stats on
> the Isoetec I see numerous Blue Alarms.
A blue alarm sounds really strange. That indicates that the remote end
(asterisk) in this case does not want to play at all. On a T1 it is sent
as a continous series of unframed 1:s. I am not sure if asterisk ever
sends a blue alarm (Alarm Indication Signal). 

Receiving a blue alarm is indicative of a serious problem. There should 
not be any audio at that time, since the blue alarm is actually a long 
unframed signal.

Peter

Kevin P. Fleming wrote:
> Geoff Manning wrote:
> 
>> The TE110P card in the Asterisk server is set as the sync source:
>> 
>> span=1,1,0,d4,ami
>> e&m=1-24
> 
> That is incorrect. You have your span configured to recover timing
> from the T1 and use that as the source for the card. If you want this
> span to be clocked using the onboard clock on the board, you must use:
> 
> span=1,0,0,d4,ami
I though setting it at 0 was to tell asterisk not to be the source of the
timing. When I set it at 1 I get slip errors inplace of the blue alarms. I
must have had my logic backwards.

Thanks,
Geoff

Peter Svensson wrote:
> A blue alarm sounds really strange. That indicates that the remote end
> (asterisk) in this case does not want to play at all. On a T1 it is
> sent as a continous series of unframed 1:s. I am not sure if asterisk
> ever sends a blue alarm (Alarm Indication Signal).
> 
> Receiving a blue alarm is indicative of a serious problem. There
> should not be any audio at that time, since the blue alarm is
> actually a long unframed signal.
> 
Well that would explain the choppy/stuttering sound we get on these calls
since there is no audio during those error transmissions.

According to Kevin's reply I had my timing logic backwards. Should I be
using any other timing settings on the Asterisk side?? The tech for our
legacy PBX says that the PBX will not provide any timing.

Thanks,
Geoff

Kevin P. Fleming wrote:
> Geoff Manning wrote:
> 
>> The TE110P card in the Asterisk server is set as the sync source:
>> 
>> span=1,1,0,d4,ami
>> e&m=1-24
> 
> That is incorrect. You have your span configured to recover timing
> from the T1 and use that as the source for the card. If you want this
> span to be clocked using the onboard clock on the board, you must use:
> 
> span=1,0,0,d4,ami

OK. So I changed it to:

span=1,0,0,d4,ami

And the Blue Alarms are still occurring but now in conjunction with Slip
errors. I feel like I am on the right track though.

Another thing that is happening now is every once and a while all the
channels on the span will open up and then timeout like so:

    -- Starting simple switch on 'Zap/1-1'
    -- Starting simple switch on 'Zap/2-1'
    -- Starting simple switch on 'Zap/3-1'
    -- Starting simple switch on 'Zap/4-1'
    -- Starting simple switch on 'Zap/5-1'
    -- Starting simple switch on 'Zap/6-1'
    -- Starting simple switch on 'Zap/7-1'
    -- Starting simple switch on 'Zap/8-1'
    -- Starting simple switch on 'Zap/9-1'
    -- Starting simple switch on 'Zap/10-1'
    -- Starting simple switch on 'Zap/11-1'
    -- Starting simple switch on 'Zap/12-1'
    -- Starting simple switch on 'Zap/13-1'
    -- Starting simple switch on 'Zap/14-1'
    -- Starting simple switch on 'Zap/15-1'
    -- Starting simple switch on 'Zap/16-1'
    -- Starting simple switch on 'Zap/17-1'
    -- Starting simple switch on 'Zap/18-1'
    -- Starting simple switch on 'Zap/19-1'
    -- Starting simple switch on 'Zap/20-1'
    -- Starting simple switch on 'Zap/21-1'
    -- Starting simple switch on 'Zap/22-1'
    -- Starting simple switch on 'Zap/23-1'

Then they will timeout and hangup. I was on a call when this happened
(Zap/24-1) and it didn't hang me up. But sometimes it will terminate my call
when it happens.

On Fri, 12 Aug 2005, Geoff Manning wrote:
> OK. So I changed it to:
> 
> span=1,0,0,d4,ami
> 
> And the Blue Alarms are still occurring but now in conjunction with Slip
> errors. I feel like I am on the right track though.
Which side shows the slips?

I am not that familiar with T1, Are you sure the signalling between the 
pbx and asterisk is set the same on both?

Peter

Peter Svensson wrote:
> Which side shows the slips?
The slips are seen on the legacy PBX side (Isoetec 228)
> I am not that familiar with T1, Are you sure the signalling between
> the pbx and asterisk is set the same on both?
> 
Unfortunately I am not aware of the signalling set on the Isoetec side.
Nothing in the console menu's allows me to see it and the tech said he was
unsure. Not a good answer. I have tried several signalling settings to no
avail.

Peter Svensson wrote:
> I am not that familiar with T1, Are you sure the signalling between
> the pbx and asterisk is set the same on both?
> 
I have unearthed some documentation on the programming side of the legacy
PBX. I can set the following on the PBX for each line on the T1 card:

Line Type:

0	immediate return on signalling
1*	wink start, return supervision on answer
2	wink start, return supervision on ring
3	return supervision on answer
4	return supervision on ring

I have tried all of those setting and nothing seemed to have any affect. But
I feel those settings in conjunction with some settings in zaptel/zapata
conf files may help. I am going to try some out, any ideas are welcome!

* It is currently set at 1

Geoff Manning wrote:
> Peter Svensson wrote:
> 
> 
>>I am not that familiar with T1, Are you sure the signalling between
>>the pbx and asterisk is set the same on both?
>>
> 
> 
> I have unearthed some documentation on the programming side of the legacy
> PBX. I can set the following on the PBX for each line on the T1 card:
> 
> Line Type:
> 
> 0	immediate return on signalling
> 1*	wink start, return supervision on answer
> 2	wink start, return supervision on ring
> 3	return supervision on answer
> 4	return supervision on ring
> 
> I have tried all of those setting and nothing seemed to have any affect.
But
> I feel those settings in conjunction with some settings in zaptel/zapata
> conf files may help. I am going to try some out, any ideas are welcome!
> 
> * It is currently set at 1
Those options are all related to per circuit call signaling.  blue 
alarms refer to timing errors on the T1  i.e. timing loss such that an 
entire frame is either dropped or repeated.

You need to be looking at a "lower" level

Bruce Ferrell wrote:
> You need to be looking at a "lower" level
Like hw/cabling errors?? If so, that's what I was afraid of for cost
reasons.

Jon Pounder wrote:
>> Geoff Manning wrote:
>>> Bruce Ferrell wrote:
>>> 
>>> 
>>>> You need to be looking at a "lower" level
>>> 
>>> 
>>> Like hw/cabling errors?? If so, that's what I was afraid of for
cost
>>> reasons.
> 
> just out of curiousity - what are you paying for a T1 cable that you
> are worried about cost ? you do realize any old ethernet cable will
> work right ? we are only talking about 1/8th to 1/80th of the speed.
> 
>
 
What? Do you think nickels grow on trees? ;)

I was concerned more about the pricing of a T1 *card*, Cabling I'm not
concerned with.

Jon Pounder wrote:
>> Bruce Ferrell wrote:
>> 
>>> You need to be looking at a "lower" level
>> 
>> Like hw/cabling errors?? If so, that's what I was afraid of for
cost
>> reasons.
> 
> no - the stuff you found relates to configuring one 64k channel of
> the T1, you need to find the settings to configure the overall t1.
> 
> - someone mentioned the encoding settings - its not that or you would
> be getting more than just a blue alarm, it would not be working
> period. 
> 
> - you need to look for clock source settings, and set those.
> 
> have your asterisk t1 card generate the clock on the asterisk TX side
> for sure. it sounds like the pbx just generates its own tx clock
> based on the rx data which is what you want (that might be faulty who
> knows). if it can generate its own tx clock from a crystal try that
> instead and see if it helps.
> 
Thanks Jon. I'm not savvy enough in this arena to completely understand your
suggestions.

I have the asterisk t1 card providing the timing as I understand it:
span=1,0,0,d4,ami

I found these settings on the legacy PBX as well, not sure if they mean
anything:

drop pulse: 014
pause time: 005s
flash time: 025*50ms
Orbit recall: 120*10s


Do these relate to /etc/asterisk/zapata.conf settings like so:

; A variety of timing parameters can be specified as well
; Including:
;    prewink:     Pre-wink time (default 50ms)
;    preflash:    Pre-flash time (default 50ms)
;    wink:        Wink time (default 150ms)
;    flash:       Flash time (default 750ms)
;    start:       Start time (default 1500ms)
;    rxwink:      Receiver wink time (default 300ms)
;    rxflash:     Receiver flashtime (default 1250ms)
;    debounce:    Debounce timing (default 600ms)
;    emdigitwait: Time to wait for DID digits on E&M links (default 250ms)
(Increase to 500
;                 or so if you are not getting all DID digits on your E&M
link)

Thanks,
Geoff

> A red alarm means "I don't see any signal".  A blue alarm
means "I
> see a signal and something downstream (repeater etc) is saying they
> don't see 
> a signal".
> 
> I used this as my reference:
> http://www.fratec.com/FAQ/NFO/NFO_WAN_009.HTML
> 
> 
> Slips sometimes cause an LOF condition, sometimes they don't.  At
> least when I worked NorTel DMS250 switches back in the 80's that's
> the way it was. 
> 
> Thanks for making me stretch my mind!
So I had an old Digium wildcard sitting around that I put inplace of the new
TE110P and the Blue Alarms seem to have cleared. There are still SLIP errors
and the call quality still sounds bad compared to the SIP only calls.

Now that I've looked back over my work for the past few days I realize that
I was trying to play with the txgain/rxgain to adjust the levels and hope to
smooth out the line noise. Well, any integer other than zero for either of
those values causes BLUE alarms and all the channels to reset in Asterisk. 

SO, my problem now is related to SLIP errors. I still have all the same line
noise as I have but the only errors I am seeing are Slip error.

PS: Thanks for all the help so far.

Thanks,
Geoff