Step 2: Display Real-Time Statistics about an Interface

Action

To display real-time statistics about traffic passing through an interface on the router, use the following JUNOS CLI operational mode command:

user@host> monitor interface interface-name

Sample Output

user@R1> monitor interface so-0/0/1 

Next='n', Quit='q' or ESC, Freeze='f', Thaw='t', Clear='c', Interface='i'

R1

Interface: so-0/0/1, Enabled, Link is Up

Encapsulation: PPP, Keepalives, Speed: OC3 Traffic statistics:

  Input bytes:                    5856541 (88 bps)

  Output bytes:                   6271468 (96 bps)

  Input packets:                   157629 (0 pps)

  Output packets:                  157024 (0 pps)

Encapsulation statistics:

  Input keepalives:                 42353

  Output keepalives:                42320

  LCP state: Opened

Error statistics:

  Input errors:                         0

  Input drops:                          0

  Input framing errors:                 0

  Input runts:                          0

  Input giants:                         0

  Policed discards:                     0

  L3 incompletes:                       0

  L2 channel errors:                    0

  L2 mismatch timeouts:                 0

  Carrier transitions:                  1

  Output errors:                        0

  Output drops:                         0

  Aged packets:                         0

Active alarms : None

Active defects: None

SONET error counts/seconds:

  LOS count                             1

  LOF count                             1

  SEF count                             1

  ES-S                                 77

  SES-S                                77

SONET statistics:

  BIP-B1                                0

  BIP-B2                                0

  REI-L                                 0

  BIP-B3                                0

  REI-P                                 0

Received SONET overhead:  F1        : 0x00  J0        : 0xZ

What It Means

The sample output shows the input and output packets for a particular SONET interface (so-0/0/1). The information can include common interface failures, such as SONET/SDH and T3 alarms, loopbacks detected, and increases in framing errors. For more information, see Track Error Conditions.

To control the output of the command while it is running, use the keys shown in Table 37.

Table 37: Monitor Interface Output Control Keys

Action	Key
Display information about the next interface. The monitor interface command scrolls through the physical or logical interfaces in the same order that they are displayed by the show interfaces terse command.	N
Display information about a different interface. The command prompts you for the name of a specific interface.	I
Freeze the display, halting the display of updated statistics.	F
Thaw the display, resuming the display of updated statistics.	T
Clear (zero) the current delta counters since monitor interface was started. It does not clear the accumulative counter.	C
Stop the monitor interface command.	Q

See the JUNOS System Basics and Services Command Reference for details on using match conditions with the monitor traffic command.