[Asterisk-Users] TE110P flashing red/green when PRI connected

[Fredrik Lithén]

Thanks for the clarification on "code blue"

Yup, the first thing I altered was to set span=1,1... as I thought that
the clocksync was the issue.

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Peter Svensson
Sent: den 9 augusti 2005 10:32
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: RE: [Asterisk-Users] TE110P flashing red/green when PRI connected

On Tue, 9 Aug 2005, Fredrik Lithén wrote:

> Yes, I tried that but it sent me a bit offtrack as it reported "blue"
> which I assumed was a clocksync problem, or at least, that was the 
> info I could find.

As far as I can tell zttool/zaptel uses the term BLue Alarm for the E1 term AIS (Alarm Indication Signal) which is a layer 2 signal sent by someone in the receive path (not necesarrily the PSTN end itself) indicating that no valid incoming signal is present. 

A bitstream is present at the receiver, though it is unframed and invalid (i.e. the receiver is seeing a transmitter that does not quite know what to transmit). This is different from a red alarm where there is no bitstream at all.

One common cause for the blue alarm is when the PSTN end shuts down an interface that has many errors. This si common practice and is probably what happend when there was a mismatch in the crc setting. 

> As it turned out, my provider didn't have error correction enabled so 
> after have endured painstaking task of getting hold of the right 
> person to talk to :) the problem was swiftly fixed.

An additional point: in the original post you mentioned that your zaptel line looked like
  span=1,0,0,ccs,hdb3,crc4
which should almost certainly be
  span=1,1,0,ccs,hdb3,crc4
since you want to synchronize your clock rate to that of the PSTN provider. With your old setting you will occasionally get a slip. Normally not a major problem, but it can wreck havoc with data transmissions (Unrestricted Digital) or in some cases with the D channel signalling.

Peter



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