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Troubleshoot Cellular Interfaces

This article describes how to monitor the status of cellular interfaces in vEdge routers and how to troubleshoot problems for these interfaces.

Monitor Cellular Interfaces

You can verify signal strength and service availability using either vManage NMS or the LED on the vEdge router. You can view the last-seen error message for cellular interfaces from vManage NMS.

Verify Signal Strength Using vManage NMS

To check signal strength and service availability of a cellular connection from vManage NMS:

  1. In vManage NMS, select the Monitor ► Network screen.
  2. From the Device Groups drop-down list in the left pane, select the device group to which the router belongs.
  3. Choose the options in the Sort by drop-down to sort the device list by status, hostname, system IP, site ID, or personality.
  4. Select the vEdge router.
  5. In the screen that opens, select Real Time in the left pane.
  6. From the command drop-down located in the right pane, select Cellular Status. The value for Signal Strength should be Excellent. If signal strength is Good, Fair, Poor, or No Signal, see Insufficient Radio Signal Strength, below.

CLI equivalent: show cellular status

  1. From the command drop-down located in the right pane, select Cellular Radio. This screen shows the values for the different cellular signals. If signal strength is Good, Fair, Poor, or No Signal, see Insufficient Radio Signal Strength, below..

CLI equivalent: show cellular status

Verify Radio Signal Strength Using the Router's LED

To check signal strength and service availability of a cellular connection from the vEdge router, look at the WWAN Signal Strength LED. This LED is lon the front of the vEdge 100m and vEdge 100wm routers, and it is labeled with a wireless icon.

The following table explains the LED color and associated status:

Color Signal Strength State Description
Off LTE interface disabled (that is, admin status is down) or not configured
Green Excellent Solid LTE interface enabled and in dormant mode (no data being received or transmitted)
    Blinking LTE interface enabled and in active mode (data being received and transmitted)
Yellow Good Solid LTE interface enabled and in dormant mode (no data being received or transmitted)
    Blinking LTE interface enabled and in active mode (data being received and transmitted)
Orange Poor Solid LTE interface enabled and in dormant mode (no data being received or transmitted)
    Blinking LTE interface enabled and in active mode (data are being received and transmitted)
Red Critical Issue Solid

LTE interface enabled but faulty; issues include no connectivity with the base transceiver station (BTS) and no signal

View Error Messages for Cellular Interfaces

To view the last-seen error for cellular interfaces from vManage NMS:

  1. In vManage NMS, select the Monitor ► Network screen.
  2. Select the device from the left pane.
  3. IIn the screen that opens, select Real Time in the left pane.
  4. From the command drop-down located in the right pane, select Cellular Status. The output displayed includes a column for Last Seen Error.

CLI equivalent: show cellular status

Resolve Problems with Cellular Interfaces

This section describes the most common issues and error messages that occur with cellular connections from the vEdge router to the cellular network, and the steps to resolve them.

Insufficient Radio Signal Strength

Problem Statement

The cellular module in the vEdge router cannot detect a radio signal from the service provider network.

Identify the Problem

  • The signal strength displayed in the vManage Cellular Status screen or with the show cellular status CLI command, or in the Cellular Radio screen or with the show cellular radio command is no signal, poor, or good. It should be excellent.
    The following table lists the ranges of signal strengths:
Signal Excellent Good Fair Poor No Signal
Received signal strength indicator (RSSI) > –58 dBm –81 through –58 dBm –82 through –95 dBm < –96 dBm
Reference signal receive power (RSRP)  –44 through –90 dBm –91 through –105 dBm –106 through –120 dBm –121 through –140 dBm < –140 dBm
Reference signal receive quality (RSRQ) –3 through –8 dB –9 through –12 dB –13 through –20 dB < –20 dB
Signal-to-noise ratio (SNR) > 10 dB 6 through 10 dB 0 through 5 dB < 0 dB
  • The wireless LED on the vEdge router is lit (solid or blinking) and is red, orange or yellow, or it is blinking green. It should be solid green.

Resolve the Problem

  1. Examine the router to verify that both basic antennas are correctly installed.
  2. Contact the service provider to verify that the location has coverage.
  3. Move the router to a new location within the building.
  4. Procure an additional external cabled antenna and connect it to the vEdge router.

Modem Status Remains in Low-Power Mode

Problem Statement

End users cannot connect to the cellular network, and the modem status remains in low-power mode.

Identify the Problem

  • End users cannot connect to the cellular network.
  • The error message "Missing or unknown APN" is generated.
  • The signal strength is less than excellent.

Resolve the Problem

  1. Verify that there is sufficient radio signal strength. If there is not, follow the instructions in Insufficient Radio Signal Strength, above.
  2. Verify that the cellular0 interface is operational. When the cellular interface is shut down, the modem status is set to Low Power mode. To to this in vManage NMS, from the Monitor ► Network screen, select the vEdge router. Then click Real Time, and in the command drop-down, select Interface Detail. To do this from the CLI, use the show interface command. Check that the Admin Status and Oper Status values are both Up.
  3. Verify that the modem temperature is not above or below the threshold temperatures. To display the modem temperature in vManage NMS, from the Monitor ► Network screen, select the vEdge router. Then click Real Time, and in the command drop-down, select Cellular Modem. From the CLI, use the, use the show cellular modem command.
  4. Check that the access point name (APN) in the profile for the cellular0 interface matches the name expected by your service provider. Some service provides required that you configure the APN, and they include configuration instructions in the SIM card package.
    1. To check which APN name is configured, in vManage NMS, from the Monitor ► Network screen, select the vEdge router. Then click Real Time, and in the command drop-down, select Cellular Profiles. From the CLI, use the, use the ;show cellular profiles command. The APN columns shows the name of the APN.
      Each profile specifies an access point name (APN), which is used by the service provider to determine the correct IP address and connect to the correct secure gateway. For some profiles, you must configure the APN.
    2. If the APN is not the one required by the service provider, configure the correct APN. In in vManage NMS, from the Configuration ► Templates screen, use the Cellular-Profile feature template. To configure this from the CLI, use the cellular cellular0 profile apn command.
  5. If none of the previous steps works, reset the cellular interface. See Reset an Interface.

Error Messages

The following table list the most common error messages that are displayed regarding cellular interfaces:

Error Message Problem Statement How Do I Fix the Problem
Authentication failed End user authentication failed, because the service provider cannot authenticate either the user's SIM card or the vEdge router's SIM card.

Contact the cellular service provider.

Illegal ME The service provider denied access to an end user, because the end user is blacklisted in the network. Contact the cellular service provider.
Illegal MS The service provider denied access to an end user, because the end user failed the authentication check. Contact the cellular service provider.
Insufficient resources

The service provider network is experiencing congestion because of insufficient resources and cannot provide the requested service to an end user.

The vEdge router automatically tries to reconnect. (The duration between retries depends on the service provider.) If the issue does not resolve itself, contact the cellular service provider.

IPV4 data call throttled The SIM card being used in the vEdge router requires that you configure static APN. Verify whether the data plan associated with the SIM card requires a static APN. If so, change the APN to the name specified the SIM card instructions, as described in Modem Status Remains in Low-Power Mode, above.
Missing or unknown APN

End users cannot connect to the cellular network, either because an APN is required and is not included in the cellular profile or because the APN could not be resolved by the service provider.

See the profile's APN, as described in Modem Status Remains in Low-Power Mode, above.
MS has no subscription for this service The service provided denied access to an end user, because the end user has no subscription. Contact the cellular service provider.

Network failure

The service provider network is experiencing difficulties. The vEdge router automatically tries to reconnect. (The duration between retries depends on the service provider.) If the issue does not resolve itself, contact the cellular service provider.

Network is temporarily out of resources

The service provider network is experiencing congestion because of insufficient resources and cannot provide the requested service to an end user.

The vEdge router automatically tries to reconnect. (The duration between retries depends on the service provider.) If the issue does not resolve itself, contact the cellular service provider.

Operator has barred the UE The service provided denied access to an end user, because the operator has barred the end user. Contact the cellular service provider.

Requested service option not subscribed

The SIM card being used in the vEdge router requires that you configure a static APN entry. Verify whether the data plan associated with the SIM card requires a static APN. If so, change the APN to the name specified the SIM card instructions, as described in Modem Status Remains in Low-Power Mode, above.

Service not supported by the PLMN

The Public Land Mobile Network (PLMN) does not support data service.

Contact the cellular service provider.

Release Information

Introduced in vManage NMS in Release 16.1.

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