I P - D S U U s e r ’ s M a n u a l
02/02/08
38
7 T R O U B L E S H O O T I N G
Troubleshooting an
IP-DSU
configuration is often a direct correlation of symptom and
cause. When armed with a few basic troubleshooting techniques, determining the source
of a problem should be easy.
It will be necessary to observe problem indicators and take appropriate actions to
localize the cause of problems. Problem indicators typically include non-zero error
counters displayed to the console, the inability to communicate between
IP-DSU
units,
and the inability to communicate between the
IP-DSU
and the BNS node. Problems may
require the gathering of measurements and/or running of diagnostic tests from the
IP-
DSU
console.
Become familiar with the
loopback
command. It is essential to diagnose failed
communications between the
IP-DSU
and the BNS node.
The
ping
diagnostic is used in IP networks to test reachability of IP destinations by
sending them an ICMP echo request and waiting for a reply. It is essential in the case of
failed communications between peer
IP-DSU
units.
The StarKeeper® II NMS supports
ping
, and can be used to test
IP-DSU
10BaseT
interface functionality. From the StarKeeper console, execute the following:
/etc/ping <ip address> [return]
where
<ip address>
is the address of the
IP-DSU
(entered using the
local
command).
Further information on command parameters can be obtained by running the Unix®
man
command for
ping
.
e.g.
man ping
[return]
Faulty hardware is always a possible cause of problems. Having spare parts available,
including a spare cable and an additional
IP-DSU,
can significantly reduce start-up time
and communication outages.
7.1 Troubleshooting
Strategies
A basic troubleshooting strategy can help pinpoint faults in an
IP-DSU
installation. The
installation may vary between sites. One case may involve substituting
IP-DSU
units into
a functioning DSU configuration. Another case may involve installing
IP-DSU
units in a
new network of BNS nodes and IP devices. In either case, installation errors may cause
an extended service outage.
Consider executing any or all of the following strategies to localize the point(s) of failure
in an
IP-DSU
installation.
7.1.1 Examine
IP-DSU
and BNS Node Console Output
Example:
Observing non-zero
IP-DSU
error counters, such as Ethernet Tx, which
indicates carrier sense lost. This may be an integrity problem with a 10BaseT
connection, so the LAN cable and hub should be checked for proper operation.
Example:
On the BNS node console, observing Loss of Frame alarms coming from the
BNS trunk module connected to the
IP-DSU
usually points to a clocking mismatch
