Ошибки E1

 LOS = Loss of Signal. You aren't getting signal.

LOF = Loss of Framing. Your packets aren't getting through framed correctly.

AIS = receiving Alarm Indicator Signal. The far end isn't getting things through framed correctly, and is indicating that back to you.

RAI = Remote Alarm Indicator. The far end is getting an error and is signalling that back to you.

There's really not much more to it than that.

To solve almost all of them, mostly involve the telco, because most

CPE type gear is so reliable now-a-days. You can reboot the CPE and

see if it clears it. If not, its most likely in the telco or the line

somewhere.

Ie. if you get a LOS, check the cabling from the hand off. Possibly

put a hard loop at the CPE back to the telco. Ask the telco if they

see it. If not, have them come out to fix it.

If you are getting a LOF, check to make sure your framing

configuration is the same on both sides. If so, ask the telco to come

out and fix it. AIS, same thing (although I remember the olden days

when CSU/DSU's wedged up and gave blue alarms from time to time).

RAI can be considered the same as the AIS alarm.