Monitoring Overview

Junos OS supports a suite of J-Web tools and CLI operational mode commands for monitoring the system health and performance of your device. Monitoring tools and commands display the current state of the device. (To use the J-Web interface and CLI operational tools, you must have the appropriate access privileges. For more information about configuring access privilege levels, see Adding New Users and the Junos System Basics Configuration Guide.)

You can use the J-Web Monitor and Manage options to monitor a device. J-Web results are displayed in the browser.

You can also monitor the device with CLI operational mode commands. CLI command output appears on the screen of your console or management device, or you can filter the output to a file. (For complete descriptions of CLI operational mode commands, see the Junos OS CLI Reference, the Junos System Basics and Services Command Reference, the Junos Interfaces Command Reference, and the Junos Routing Protocols and Policies Command Reference.)

This section contains the following topics:

Monitoring Terms
Filtering Command Output

Monitoring Terms

Before monitoring your device, become familiar with the terms defined in Table 50.

Table 50: Monitoring Terms

Term	Definition
autonomous system (AS)	Network of nodes that route packets based on a shared map of the network topology stored in their local databases.
Internet Control Message Protocol (ICMP)	TCP/IP protocol used to send error and information messages.
routing table	Database of routes learned from one or more protocols.

Filtering Command Output

For operational commands that display output, such as the show commands, you can redirect the output into a filter or a file. When you display help about these commands, one of the options listed is |, called a pipe, which allows you to filter the command output.

For example, if you enter the show configuration command, the complete device configuration is displayed on the screen. To limit the display to only those lines of the configuration that contain address, issue the show configuration command using a pipe into the match filter:

user@host> show configuration | match
address

                     address-range low 192.168.3.2 high 192.168.3.254; address-range low 192.168.71.71 high 192.168.71.254;  address 192.168.71.70/21; address 192.168.2.1/24; address 127.0.0.1/32;

For a complete list of the filters, type a command, followed by the pipe, followed by a question mark (?):

user@host> show configuration | ?

Possible completions:   compare              Compare configuration changes with prior version   count                Count occurrences   display              Show additional kinds of information   except               Show only text that does not match a pattern   find                 Search for first occurrence of pattern   hold                 Hold text without exiting the --More-- prompt   last                 Display end of output only   match                Show only text that matches a pattern   no-more              Don't paginate output   request              Make system-level requests   resolve              Resolve IP addresses   save                 Save output text to file   trim                 Trim specified number of columns from start of line

You can specify complex expressions as an option for the match and except filters. For more information about command output filtering and creating match expressions, see the Junos CLI User Guide.

Note: To filter the output of configuration mode commands, use the filter commands provided for the operational mode commands. In configuration mode, an additional filter is supported. See the Junos CLI User Guide.