At 04:56 PM 8/10/2001 +0200, Erik Drost wrote:
>Hi,
>
>I have a problem with a VWIC using G.703 in an NM-2FE2W on a Cisco 3620
>(IOS 12.2.1 IP featureset). The E1 serial line is down and a "show
>controller E1" shows a "Receiver is getting AIS" error message (framing,
>impedance and linecode are configured correctly):
Here is what is going on:
If the network element detects serious problem
is raised a red alarm, and
+--------+
------>| NE | -----------> your receiver
<------| |<-----------
+--------+
^ AIS (blue) is transmitted here
^ Yellow alarm is transmitted here
So if you are receiving a clean AIS you are getting a good signal
from the closest Network Element to your receiver, the problem is
further upstream. Now of course the problem might not be the nearest
Network Element to you, it could be happening anywhere along the way.
The idea is that the AIS (sometimes called all-ones or a blue alarm for
those with a US telco history.) provides the remaining network elements
a signal to prevent problems.
If you make sure you are transmitting a good signal (assuming
you control both end points), the problem is in the network between
your two endpoints.
If you can see the NE (usually not, unless you are the telco) it
will have an more informative alarm on it if it is the one generating
the AIS. If it is just regenerating the AIS, obviously it will be
receiving an AIS also. You just continue back towards the source
until you find the problem.
Hope this helps a little...
See ya,
ww3
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