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

[Peter Svensson]

On Tue, 9 Aug 2005, Andrew Kohlsmith wrote:

> On Tuesday 09 August 2005 04:32, Peter Svensson wrote:
> > 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.
> 
> I thought that red alarm was when it wasn't receiving a properly framed 
> signal, and it sent an unframed all-1s pattern to the far end.  Yellow alarm 
> was when it was seeing an unframed all-1s pattern and was then trying to send  
> a properly framed signal to the far side?

I believe you are correct regarding the red alarm. Red alarm is declared 
when a frame loss has persisted for more than 2.5s. It is a local alarm. 
A framing error is a neccesary consequence of a LOS. :-)

Yellow alarm (Remote Alarm Indication) is sent when a frame error 
condition exists in the receiver. On a T1 it is sent in bit 2 of 
every frame (for D4) or through a pattern in ESF. For an E1 two separate 
errors indications are collectivly known as yellow alarm, loss of framing 
(sets the A bit) or loss of multiframeing (sets the Y bit).

Blue alarm (Alarm Indication Signal) is sent when the remote end does not 
want to communicate. It is sent as unframed 1.

> I seem to remember blue and yellow alarm being the same thing bu tit's 6am 
> here and the mind is very much foggy.  :-)

Blue alarm - the other end is either administrativly down or there is a 
disconnect between various layers somewhere along the receive path.

Peter