Syslog Questions

Question 1

Explanation

The Message Logging is divided into 8 levels as listed below:

Level	Keyword	Description
0	emergencies	System is unusable
1	alerts	Immediate action is needed
2	critical	Critical conditions exist
3	errors	Error conditions exist
4	warnings	Warning conditions exist
5	notification	Normal, but significant, conditions exist
6	informational	Informational messages
7	debugging	Debugging messages

The highest level is level 0 (emergencies). The lowest level is level 7. If you specify a level with the “logging console level” command, that level and all the higher levels will be displayed. For example, by using the “logging console warnings” command, all the logging of emergencies, alerts, critical, errors, warnings will be displayed.

Question 2

Explanation

Syslog can be configured to send messages to an external server for storing. The storage size does not depend on the router’s resources and is limited only by the available disk space on the external Syslog server. For example, to instruct our router to send Syslog messages to 192.168.1.2 we can simply use only this command (all parameters are at default values):

R1(config)#logging 192.168.1.2

We cannot send other options (terminal, buffer, console) to external server.

Question 3

Explanation

The “service timestamps log uptime” enables timestamps on log messages, showing the time since the system was rebooted. For example:

00:00:46: %LINK-3-UPDOWN: Interface Port-channel1, changed state to up

Question 4

Explanation

Syslog levels are listed below:

Level	Keyword	Description
0	emergencies	System is unusable
1	alerts	Immediate action is needed
2	critical	Critical conditions exist
3	errors	Error conditions exist
4	warnings	Warning conditions exist
5	notification	Normal, but significant, conditions exist
6	informational	Informational messages
7	debugging	Debugging messages

Number “5” in “%LINEPROTO-5- UPDOWN” is the severity level of this message so in this case it is “notification”.

Question 5

Explanation

Maybe this question wants to mention about this Syslog message:

00:00:47: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/1, changed state to up

-> The log secerity level of this warning is 3 – errors

Question 6

Question 7

Question 8

Explanation

“Increase the logging history” here is same as “increase the logging buffer”. The default buffer size is 4096 bytes. By increasing the logging buffer size we can see more history logging messages. But do not make the buffer size too large because the access point could run out of memory for other tasks. We can write the logging messages to a outside logging server instead.