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 _______________________________________________ Asterisk-Users mailing list Asterisk-Users@lists.digium.com http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
