chapter thirty one

31 Syslog

 

This chapter covers

  • Real-time logging to the console and VTY lines
  • Storing log messages locally and on a Syslog server
  • The Syslog message format
  • Syslog severity levels

Syslog is a standard for message logging in computers, and is CCNA exam topic 4.5: Describe the use of syslog features including facilities and levels. Like SNMP, the topic of the previous chapter, Syslog provides mechanisms to collect information about devices and monitor network health.

Although they do have their similarities, there are significant differences between SNMP and Syslog, and for that reason most networks make use of both protocols. SNMP is like a network health report, proactively polling devices at regular intervals to gather mostly (but not exclusively) quantitative metrics—numerical statistics like traffic rates, CPU utilization, error rates, etc. SNMP is also often used for event-based alerting using Trap and Inform messages.

31.1 Viewing device logs

31.1.1 Real-time logging

31.1.2 The logging synchronous command

31.1.3 Storing logs

31.2 The Syslog message format

31.2.1 Sequence numbers and timestamps

31.2.2 Syslog severity levels

31.2.3 The debug command

31.3 Summary