Information Technology Reference
In-Depth Information
Table15-5 Serial Lines: Troubleshooting Serial Line Input Errors (continued)
Input Error Type
(Field Name)
Possible Problem
Solution
Framing errors
(frame)
A framing error
occurs when a
packet does not
end on an 8-bit
byte boundary for
one of the
following reasons:
Ensure that the line is clean enough for
transmission requirements. Shield the
cable, if necessary. Make certain that you
are using the correct cable.
1.
Make sure that the cable is within the
recommended length (no more than 50
feet [15.24 meters], or 25 feet [7.62
meters] for a T1 link).
2.
The serial line
is noisy
Ensure that all devices are properly
configured to use a common line clock.
Set SCTE on the local and remote DSU.
If your CSU/DSU does not support
SCTE, see the section “Inverting the
Transmit Clock,” later in this chapter.
3.
The cable is
improperly
designed; the
serial cable is
too long; the
cable from
the CSU or
DSU to the
router is not
shielded.
Make certain that the local and remote
CSU/DSU is configured for the same
framing and coding scheme as that used
by the leased-line or other carrier service
(for example, ESF 1 /B8ZS 2 ).
4.
SCTE mode
is not enabled
on the DSU;
the CSU line
clock is
incorrectly
configured;
one of the
clocks is
configured
for local
clocking.
Contact your leased-line or other carrier
service, and have it perform integrity tests
on the line.
5.
A ones
density
problem has
occurred on
the T1 link
(incorrect
framing or
coding
specification)
.
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