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Administering E1 and T1 Services
Troubleshooting a Red Alarm
MAX Administration Guide
5-3
For more information about the CSU and troubleshooting indicator lights, see “Integrated CSU
for T1/PRI” on page 5-4.
Verifying Framing Mode settings
You must contact your E1 or T1 service carrier to determine the correct setting to specify for
the Framing Mode parameter, which is located in the Line Config menu’s Line N profile. The
Framing Mode parameter specifies the framing mode in use on the physical links of a T1 or E1
line.
For a T1 line, the carrier can require you to specify one of the following values:
•
D4
—Specifies the superframe format, which consists of 12 consecutive frames, separated
by framing bits. Do not use this setting with ISDN D-channel signaling (when
Signaling-Mode=ISDN
).
•
ESF
—Specifies the Extended Superframe Format, which consists of 24 consecutive
frames, separated by framing bits. The ISDN specification advises that you use ESF with
ISDN D-channel signaling (when
Signaling-Mode=ISDN
).
For an E1 line, the carrier can require you to specify the following values:
•
G703
—Specifies that the trunk interface uses CRC-4.
•
2DS
—Specifies that the trunk interface does not use CRC-4.
Resolving cabling issues
If the MAX unit is connected through bantam connector plugs, reverse the transmit and receive
plugs. Then allow the unit to attempt to establish synchronization for 30 seconds. The MAX
unit uses bantam connector plugs to connect with digital circuits and digital crossover (DSX)
patch panels.
Perform a line loopback test on a RJ48C connector-plug, connect: pin 1 to pin 5 and pin 2 to
pin 4. When you plug this connector into the T1/PRI WAN port, the port should come out of
Red Alarm state on the MAX unit, no matter what Encoding or Framing Mode settings you
have specified. You should see line active (LA) in the corresponding line status window.
For more information about cables and cable specifications, see the Hardware Installation and
Basic Configuration Guide for your unit.
Summary of Red Alarm causes and solutions
Table 5-1 summarizes potential causes for a Red Alarm and the solutions that may end the Red
Alarm state.
Table 5-1. Red Alarm potential causes and solutions
Cause
Solution
Unused T1 or T1 line is
enabled
If the one of the T1 or T1 lines is unused, verify that it is disabled in the Line Config
menu’s Line N profile.