Using Span; Using The Blue Beacon Feature; Using The Watch Command - Cisco Nexus 9000 Series Troubleshooting Manual

Using SPAN

The terminal monitor command enables logging for Telnet or SSH and is disabled by default.
switch# terminal monitor
For more information about configuring syslog, see the Cisco Nexus 9000 Series NX-OS System Management
Configuration Guide.

Using SPAN

You can use the Switched Port Analyzer (SPAN) utility to perform detailed troubleshooting or to take a sample
of traffic from a particular application host for proactive monitoring and analysis.
When you have a problem in your network that you cannot solve by fixing the device configuration, you
typically need to take a look at the protocol level. You can use debug commands to look at the control traffic
between an end node and a device. However, when you need to focus on all the traffic that originates from
or is destined to a particular end node, you can use a protocol analyzer to capture protocol traces.
To use a protocol analyzer, you must insert the analyzer inline with the device under analysis, which disrupts
input and output (I/O) to and from the device.
In Ethernet networks, you can solve this problem by using the SPAN utility. SPAN allows you to take a copy
of all traffic and direct it to another port within the device. The process is nondisruptive to any connected
devices and is facilitated in the hardware, which prevents any unnecessary CPU load.
SPAN allows you to create independent SPAN sessions within the device. You can apply a filter to capture
only the traffic received or the traffic transmitted.
For more information about configuring SPAN, see the Cisco Nexus 9000 Series NX-OS System Management
Configuration Guide.

Using the Blue Beacon Feature

On some platforms, you can cause the platform LEDs to blink. This feature is a useful way to mark a piece
of hardware so that a local administrator can quickly identify the hardware for troubleshooting or replacement.
To flash the LEDs on a hardware entity, use the following commands:
Command
blink chassis
blink fan number
blink module slot
blink powersupply number

Using the watch Command

The watch command allows you to refresh and monitor Cisco NX-OS CLI command output or Unix command
output (through the run bash command command).
Use the command as follows:
Cisco Nexus 9000 Series NX-OS Troubleshooting Guide, Release 7.x
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Troubleshooting Tools and Methodology
Purpose
Flashes the chassis LED.
Flashes one of the fan LEDs.
Flashes the selected module LED.
Flashes one of the power supply LEDs.