Re: (PM) Bi polar violations? (fwd)

Kyle Platts (kwplat1@uswest.com)
Tue, 26 May 1998 09:56:38 -0500

Jeff Halper wrote:
>
> I am looking for info on the meaning of the various alarms - yellow, blue,
> receive carrir loss, loss of synch, and on the various violations -
> bipolar, crc, multiframe synch.
>
> What do they mean? Is the existence of these errors indicate a problem
> with my portmaster 3, the pacific bell line, or both? WHat can I do about
> these?

Yellow Alarm - This is an all ones signal coming into the PM3. This
comes from the network to signal there is a problem in the opposite (the
transmit of the PM3) direction.

Blue Alarm - This is also an all ones signal coming into the PM3,
however this signal is generated by a piece of network equipment to
signal there is a problem coming into it. An intelligent piece of
equipment won't pass a bad signal, and sends an all ones to keep the
span alive.

Receive Carrier Loss - loss of received signal, or Red Alarm

Loss of Synch - This is a gray area. Livingston says it means there were
192 consecutive zeroes. I would think it means it did not find the
framing bit where it expected to.

Bi-Polar - T1's use Alternate Mark Inversion, a bi-polar signifies there
were two consecutive pulses of the same polarity.

CRC - only valid with ESF spans. This is the CRC-6 check that is done in
the ESF overhead.

Multiframe Sync - your guess is as good as mine

>
> I had 14 yellow alarms and 343 crc violations last nite on my line0, line1
> was all zeros. Do I have a problem here? I read the URL below, but didn't
> really find meaningful answers.

Yellow alarms indicate trouble in your transmit direction. The CRC's
were probably caused by the span going into and coming out of the Yellow
alarm state.

I have a T1 primer out there. It should be in the archives and is also
available at

http://pmr.infinet.net/T1.html

-- 
Kyle Platts
Network Engineer
!NTERPRISE Networking Services
U S WEST Communications
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