Manual

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358
43.7.1.1 Log Output Channel
So far the system log can be outputted the log information through four channels:
Through Console port to the local console
Output the log information to remote Telnet terminal or monitor, this function is good for remote
maintenance
Assign a proper log buffer zone inside the switch, for record the log information permanently or
temporarily
Configure the log host, the log system will directly send the log information to the log host, and
save it in files to be viewed at any time
Among above log channels, users rarely use the console monitor, but will commonly choose
the Telnet terminal to monitor the system operation status. However information outputted from
these channels are of low traffic capacity and can not be recorded for later view. The other two
channels---the log buffer zone and log host channel are two important channels
SDRAM (Synchronous Dynamic Random Access Memory) and NVRAM (Non Vulnerable
Random Access Memory) is provided inside the switch as two part of the log buffer zone, The
two buffer zone record the log information in a circuit working pattern, namely when log
information need to be recorded exceeds the buffer size, the oldest log information will be
erased and replaced by the new log information, information saved in NVRAM will stay
permanently while those in SDRAM will lost when the system restarts or encounter an power
failure. Information in the log buffer zone is critical for monitoring the system operation and
detecting abnormal states.
Note: the NVRAM log buffer may not exist on some switches, which only have the SDRAM log
buffer zone.
It is recommended to use the system log server. By configuring the log host on the switch, the
log can be sent to the log server for future examination.
43.7.1.2 Format and Severity of the Log Information
The log information format is compatible with the BSD syslog protocol, so we can record and
analyze the log by the systlog (system log protect session) on the UNIX/LINUX, as well as
syslog similar applications on PC.
The log information is classified into eight classes by severity or emergency procedure. One
level per value and the higher the emergency level the log information has, the smaller its
value will be. For example, the level of critical is 2, and warning is 4, debugging is leveled at 7,
so the critical is higher than warnings which no doubt is high than debugging. The rule applied
in filtering the log information by severity level is that: only the log information with level equal
to or higher than the threshold will be outputted. So when the severity threshold is set to
debugging, all information will be outputted and if set to critical, only critical, alerts and