Information Technology Reference
In-Depth Information
Table15-5 Serial Lines: Troubleshooting Serial Line Input Errors (continued)
Input Error Type
(Field Name)
Possible Problem
Solution
Aborted
transmission
(abort)
Aborts indicate an
illegal sequence
of 1 bit (more than
seven in a row)
The following are
possible reasons
for this to occur:
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.
1.
Shield the cable, if necessary. Make
certain 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). Ensure that all
connections are good.
2.
SCTE mode
is not enabled
on DSU.
•
The CSU line
clock is
incorrectly
configured.
•
Check the hardware at both ends of the
link. Swap faulty equipment, as
necessary.
3.
The serial
cable is too
long, or the
cable from
the CSU or
DSU to the
router is not
shielded.
•
Lower data rates and determine whether
aborts decrease.
4.
Use local and remote loopback tests to
determine where aborts are occurring (see
the section “Special Serial Line Tests,”
later in this chapter).
5.
Contact your leased-line or other carrier
service, and have it perform integrity tests
on the line.
6.
A ones
density
problem has
occurred on
the T1 link
(incorrect
framing or
coding
specification)
.
•
A packet
terminated in
middle of
transmission
(typical cause
is an interface
reset or a
framing
error).
•
A hardware
problem has
occurred (bad
circuit, bad
CSU/DSU, or
bad sending
interface on
•
