Verifying a USB Modem Interface

Purpose

Verify that the USB modem interface is correctly configured and display the status of the modem.

Action

From the CLI, enter the show interfaces extensive command.

Physical interface: umd0, Enabled, Physical link is Up
  Interface index: 64, SNMP ifIndex: 33, Generation: 1
  Type: Async-Serial, Link-level type: PPP-Subordinate, MTU: 1504, 
Clocking: Unspecified, Speed: MODEM
  Device flags   : Present Running
  Interface flags: Point-To-Point SNMP-Traps Internal: 0x4000
  Link flags     : None
  Hold-times     : Up 0 ms, Down 0 ms
  Last flapped   : Never
  Statistics last cleared: Never
  Traffic statistics:
   Input  bytes  :                21672
   Output bytes  :                22558
   Input  packets:                 1782
   Output packets:                 1832
  Input errors:
    Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Giants: 0, Policed discards: 0, 
Resource errors: 0
  Output errors:
    Carrier transitions: 63, Errors: 0, Drops: 0, MTU errors: 0, Resource errors: 0
  MODEM status:
    Modem type                    : LT V.92 1.0 MT5634ZBA-USB-V92 Data/Fax Modem 
(Dual Config) Version 2.27m
    Initialization command string : ATS0=2
    Initialization status         : Ok
    Call status                   : Connected to 4085551515
    Call duration                 : 13429 seconds
    Call direction                : Dialin
    Baud rate                     : 33600 bps
    Most recent error code        : NO CARRIER

  Logical interface umd0.0 (Index 2) (SNMP ifIndex 34) (Generation 1)
    Flags: Point-To-Point SNMP-Traps Encapsulation: PPP-Subordinate

Meaning

The output shows a summary of interface information and displays the modem status.

Verify the following information:

• The physical interface is Enabled. If the interface is shown as Disabled, do either of the following:
  • In the CLI configuration editor, delete the disable statement at the [edit interfaces interface-name] level of the configuration hierarchy.
  • In the J-Web configuration editor, clear the Disable check box on the Interfaces>interface-name page.
• The physical link is Up. A link state of Down indicates a problem with the interface module, interface port, or physical connection (link-layer errors).
• The Last Flapped time is an expected value. The Last Flapped time indicates the last time the physical interface became unavailable and then available again. Unexpected flapping indicates likely link-layer errors.
• The traffic statistics reflect expected input and output rates. Verify that the number of inbound and outbound bytes and packets matches expected throughput for the physical interface. To clear the statistics and see only new changes, use the clear interfaces statistics interface-name command.
• The modem initialization command string has a nonzero value for the S0=n modem command. A nonzero value is required to configure the modem to automatically answer calls. For example, the command S0=2 configures the modem to automatically answer calls on the second ring.

  For more information, see Modifying USB Modem Initialization Commands.

• The modem initialization status is Ok. If the initialization status is shown as Error or Not Initialized, do the following:
  1. Verify that the modem initialization commands are valid. If the modem initialization sequence includes invalid commands, correct them, as described in Modifying USB Modem Initialization Commands.
  2. If the modem initialization commands are valid, reset the modem. For more information, see Resetting USB Modems.

Determine the following information:

• The call status
• The duration of the call

Related Topics

For a complete description of show interfaces extensive output, see the JUNOS Interfaces Command Reference.