B3 errors, in the absence of B1 and B2 errors, almost universally point to
bad transmit toward the station receiving the errors, between the PTE and
the first LTE (The mux and the router). They may be accompanied (depending
on the error threshold on the ADM) by intermittent Path AIS on the far end
(the port that you are receiving errors on). If the local fiber were bad,
you would be seeing B1 and B2s as well. If you are only seeing B3s, the
errors originate on the far end of the line, or within the carrier network
itself (which is unlikely - as they would get alarms on their ADM(s) and
address them). The B3 levels are unidirectional in scope - Path FEBE's
correspond to B3s in the opposite direction.
For example:
<>---------------*-----------*------------------<>
RTRA MUXA MUXA RTRB
RTRA has bad transmit condition (wrong mode, bad fiber, bad port, scrambling
mismatch). MUX A detects Line and Section BIP errors, and logs them (Some
LTE don't send/record Line FEBEs). If the error threshold exceeds a certain
value, MUXA generates a Loss of Frame condition, sends a Path AIS upstream,
which would trigger a PATH RDI to be sent from RTRB back to RTRA. For every
BIP3 received by RTRB, RTRA should receive a PATH FEBE error. If RTRA is
seeing BIP3s, then RTRB is has bad transmit, or there is bad transmit
somewhere in the cloud.
That being said, if you are seeing errors everyday at the same time, what
are the conditions? If load is heavy, then BIP3's increase, because parity
checks on IDLE frames aren't as accurate an error detecting mechanism on
random data frames. I agree with Cisco that it is likely a bad transmit
strand (dirty fiber) on the far end side of the router seeing the alarms.
Replace that first and see what happens.
chris
-----Original Message-----
From: Andre Dieball [mailto:adieball@beteigeuze.de]
Sent: Tuesday, September 19, 2000 4:01 PM
To: cisco-nsp@puck.nether.net
Subject: RE: SONET-4-ALARM everyday
Hi
B3 errors are definetly NOT from a dirty fiber ....
B3 is a bit which is set in the SONET frames (i believe), so the B3
comes from your carrier or the POS card is broken.
What is your carrier? I know that there was a problem with DWDM
equipment in the past at our carrier. There was a failure in their
bandwidth manager, which causes that the value of the "B3 bit" as
swapped without any reason.
Do you also see these B3 threshold exceeds on "the other end" of the
circuit?
Have you had a look in the Bugwatcher on CCO?
Rgds
Andre
> -----Original Message-----
> From: tishi@ziplink.net [mailto:tishi@ziplink.net]
> Sent: Dienstag, 19. September 2000 21:46
> To: cisco-nsp@puck.nether.net
> Subject: SONET-4-ALARM everyday
>
>
> Hi all,
>
> I am getting syslog entries listed below everyday.
> I had a TAC case but all I got from CISCO was "it's a dirty fiber".
> If that is the case, how a dirty fiber affects us everyday
> almost at the same time? I contacted a SONET provider,
> they told me that "we do not see any hit". I also see lots of
> PATH errors.
>
> any suggestions?
>
> -tishi
>
> >>>>
> Sep 14 04:44:55 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER
> exceeds threshold, TC alarm declared
> Sep 14 04:46:44 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER below
> threshold, TC alarm cleared
> Sep 15 04:44:56 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER
> exceeds threshold, TC alarm declared
> Sep 15 04:46:45 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER below
> threshold, TC alarm cleared
> Sep 16 04:44:57 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER
> exceeds threshold, TC alarm declared
> Sep 16 04:46:46 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER below
> threshold, TC alarm cleared
> Sep 17 04:44:59 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER
> exceeds threshold, TC alarm declared
> Sep 17 04:46:48 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER below
> threshold, TC alarm cleared
> Sep 18 04:44:59 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER
> exceeds threshold, TC alarm declared
> Sep 18 04:46:48 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER below
> threshold, TC alarm cleared
> Sep 19 04:45:00 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER
> exceeds threshold, TC alarm declared
> Sep 19 04:46:49 EDT: %SONET-4-ALARM: POS5/0/0: B3 BER below
> threshold, TC alarm cleared
> <<<<
>
>
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