Cisco Routers log messages can handle five different ways

Console Logging

• by default the router sends all log messages to its console port.
• these can only be viewed by those who are physically connected

Terminal logging

• displays log messages to the routers VTY lines instead. (Not enabled by default)

Buffered Logging

• uses routers RAM for storing log messages.
• buffer has a fixed size to ensure that the log will not deplete valuable system memory.
• it deletes old messages from buffer as new ones come in.

Syslog server logging

• router can use syslog to forward log messages to external syslog servers for storage.

SNMP trap logging

• the router is able to use SNMP traps to send log messages to an external SNMP server.

Logging Level Messages

0        Emergencies, system shutdown due to missing fan tray

1        Alerts, temperature limit exceeded

2        Critical, memory allocation failures

3        Errors, Interface up/down messages

4        Warnings, config file written to server

5        Notifications, Line protocol up/down

6        Information, Access list violation logging

7        Debugging, debugging messages