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monitor interface

date_range 19-Nov-23

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Syntax

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monitor interface
<interface-name | traffic <detail>>

Description

Display real-time statistics about interfaces, updating the statistics every second. Check for and display common interface failures, such as SONET/SDH and T3 alarms, loopbacks detected, and increases in framing errors.

Note:

On Junos OS Evolved, you can use the monitor interface command over SSH sessions, but console and Telnet sessions are not supported.

Note:

This command is not supported on the QFX3000 QFabric switch.

Options

none	Display real-time statistics for all interfaces.
detail	(Optional) With traffic option only, display detailed output.
`interface-name`	(Optional) Display real-time statistics for the specified interface. In a TX Matrix or TX Matrix Plus router, display real-time statistics for the physical interfaces on the specified line-card chassis (LCC) only.
traffic	(Optional) Display traffic data for all active interfaces. In a TX Matrix or TX Matrix Plus router, display real-time statistics for the physical interfaces on the specified LCC only.

Additional Information

The output of this command shows how much each field has changed since you started the command or since you cleared the counters by pressing the c key. For a description of the statistical information provided in the output of this command, see the show interfaces extensive command for a particular interface type in the CLI Explorer. To control the output of the monitor interface command while it is running, use the keys listed in Table 1. The keys are not case-sensitive.

Table 1: Output Control Keys for the monitor interface interface-name Command
Key	Action
c	Clears (returns to zero) the delta counters since `monitor interface` was started. This does not clear the accumulative counter. To clear the accumulative counter, use the `clear interfaces interval` command.
f	Freezes the display, halting the display of updated statistics and delta counters.
i	Displays information about a different interface. The command prompts you for the name of a specific interface.
n	Displays information about the next interface. The `monitor interface` command displays the physical or logical interfaces in the same order as the `show interfaces terse` command.
q or Esc	Quits the command and returns to the command prompt.
t	Thaws the display, resuming the update of the statistics and delta counters.

To control the output of the monitor interface traffic command while it is running, use the keys listed in Table 2. The keys are not case-sensitive.

Table 2: Output Control Keys for the monitor interface traffic Command
Key	Action
b	Displays the statistics in units of bytes and bits per second (bps).
c	Clears (return to 0) the delta counters in the `Current Delta` column. The statistics counters are not cleared.
d	Displays the `Current Delta` column (instead of the rate column) in bps or packets per second (pps).
p	Displays the statistics in units of packets and packets per second (pps).
q or Esc	Quits the command and returns to the command prompt.
r	Displays the rate column (instead of the `Current Delta` column) in bps and pps.

Required Privilege Level

trace

Output Fields

Table 3 describes the output fields for the monitor interface command. Output fields are listed in the approximate order in which they appear.

Table 3: monitor interface Output Fields
Field Name	Field Description	Level of Output
`router1`	Hostname of the router.	All levels
`Seconds`	How long the monitor interface command has been running or how long since you last cleared the counters.	All levels
`Time`	Current time (UTC).	All levels
`Delay x/y/z`	Time difference between when the statistics were displayed and the actual clock time. `x`—Time taken for the last polling (in milliseconds). `y`—Minimum time taken across all pollings (in milliseconds). `z`—Maximum time taken across all pollings (in milliseconds).	All levels
`Interface`	Short description of the interface, including its name, status, and encapsulation.	All levels
`Link`	State of the link: `Up`, `Down`, or `Test`.	All levels
`Current delta`	Cumulative number for the counter in question since the time shown in the Seconds field, which is the time since you started the command or last cleared the counters.	All levels
`Local Statistics`	(Logical interfaces only) Number and rate of bytes and packets destined to the router or switch through the specified interface. When a burst of traffic is received, the value in the output packet rate field might briefly exceed the peak cell rate. It usually takes less than 1 second for this counter to stabilize. `Input bytes`—Number of bytes received on the interface. `Output bytes`—Number of bytes transmitted on the interface. `Input packets`—Number of packets received on the interface. `Output packets`—Number of packets transmitted on the interface.	All levels
`Remote Statistics`	(Logical interfaces only) Statistics for traffic transiting the router or switch. When a burst of traffic is received, the value in the output packet rate field might briefly exceed the peak cell rate. It usually takes less than 1 second for this counter to stabilize. `Input bytes`—Number of bytes received on the interface. `Output bytes`—Number of bytes transmitted on the interface. `Input packets`—Number of packets received on the interface. `Output packets`—Number of packets transmitted on the interface.	All levels
Traffic statistics	Total number of bytes and packets received and transmitted on the interface. These statistics are the sum of the local and remote statistics. When a burst of traffic is received, the value in the output packet rate field might briefly exceed the peak cell rate. It usually takes less than 1 second for this counter to stabilize. `Input bytes`—Number of bytes received on the interface. `Output bytes`—Number of bytes transmitted on the interface. `Input packets`—Number of packets received on the interface. `Output packets`—Number of packets transmitted on the interface.	All levels
`Description`	With the `traffic` option, displays the interface description configured at the `[edit interfaces interface-name]` hierarchy level.	`detail`
Input Errors	Sum of incoming frame aborts and FCS errors.	All levels
Input Drops	Number of packets dropped by the input queue of the I/O Manager ASIC. If the interface is saturated, this number increments once for every packet that is dropped by the ASIC's RED mechanism.	All levels
Input Framing errors	Number of packets received with an invalid frame checksum (FCS).	All levels
Policed discards	Number of frames that the incoming packet match code discarded because they were not recognized or not of interest. Usually, this field reports protocols that the Junos OS does not handle.	All levels
L3 incompletes	Number of incoming packets discarded because they failed Layer 3 (usually IPv4) sanity checks of the header. For example, a frame with less than 20 bytes of available IP header is discarded. L3 incomplete errors can be ignored by configuring the `ignore-l3-incompletes` statement.	All levels
L2 channel errors	Number of times the software did not find a valid logical interface for an incoming frame.	All levels
L2 mismatch timeouts	Number of malformed or short packets that caused the incoming packet handler to discard the frame as unreadable.	All levels

Sample Output

monitor interface (Physical)
monitor interface (OTN Interface)
monitor interface (MX480 Router with MPC5E and 10-Gigabit Ethernet OTN Interface)
monitor interface (MX480 Router with MPC5E and 100-Gigabit Ethernet Interface)
monitor interface (MX2010 Router with MPC6E and 10-Gigabit Ethernet OTN Interface)
monitor interface (MX2010 Router with MPC6E and 100-Gigabit Ethernet OTN Interface)
monitor interface (MX2020 Router with MPC6E and 10-Gigabit Ethernet OTN Interface)
monitor interface (Logical)
monitor interface (QFX3500 Switch)
monitor interface traffic
monitor interface traffic (QFX3500 Switch)
monitor interface traffic detail (QFX3500 Switch)