What do the lights on my cable modem mean?

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Issue

How To

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Issue

Cable Modem Lights

How To

Lights on the cable modem are specific to the cable modem model. We currently have four different models of cable modems, please match your cable modem to the models below. (The lights are the same on the two Com21 models.)

Com21


FUNCTION COLOR
DEFINITION
PWR Green

- Dark for power off
- Solid for power on

RF or ST

Green

Green-Amber-Off

Blinking Green

 

- Dark - no downstream RF carrier present or power off
- Solid - cable modem is registered / provisioned and ready to transfer data
- Flashing Green-Amber-Off - ready for provisioning
- Flashing constant green - modem blocked

 

TD Blinking Green Transmit data flickers when data is transmitted to the computer
RD Blinking Green Receive data flickers when data is received from the computer.
LINK or CD Green

- Solid for ethernet connectivity when connected to a computer
- Dark for not connected to a computer

Toshiba PCX2500

FUNCTION COLOR
DEFINITION
Cable Green

- Dark - for no downstream RF carrier present or power off
- Flashing - slowly(*1) for searching the downstream RF carrier
- Flashing(*2) - for downstream RF carrier present and ranging in progress
- Flashing fast(*3) - for registration in progress, then ready for provisioning
- Flashing fast(*3) - modem blocked
- Solid - cable modem is registered / provisioned and ready to transfer data

PC Green

- Dark for no carrier signal to/from PC present or power off
- Solid for carrier to/from PC present

Data Green

- Dark for no user data going through the cable modem or power off
- Flashing for user data going though the cable modem (both upstream and downstream)
- Flashes even when the PC is turned off, but modem is functional

Test Amber

- Dark for initial self-test of the cable modem OK(*4) or power off
- Flashing for initial self-test of the cable modem in progress
- Solid for self-test failure of the cable modem (power recycle, and if light stays solid, need to swap modem)

Power Green

- Dark for power off
- Solid for power on


(*1) Flashing slowly: flashing approximately every 2 seconds
(*2) Flashing: flashing approximately every 1 second
(*3) Flashing fast: flashing approximately every 0.1 second
(*4) It takes approximately 30 seconds to complete the self-test for the cable modem after power on. Then searching the downstream RF carrier will start.

Toshiba PCX1100

FUNCTION COLOR
DEFINITION
Power Green

- Dark for power off
- Solid for power on

Cable Green

- Dark - no downstream RF carrier present or power off
- Flashing slowly(*1) - searching the downstream RF carrier
- Flashing(*2) - downstream RF carrier present and ranging in progress
- Flashing fast(*3) - registration in progress, then ready for provisioning
- Flashing fast(*3) - modem blocked
- Solid - cable modem is registered / provisioned and ready to transfer data

PC Green

- Dark for no carrier to/from PC present or power off
- Solid for carrier to/from PC present

Data Green

- Dark for no user data going through the Cable Modem or power off
- Flashing for user data going though the cable modem (both upstream and downstream)
- Flashes even when the PC is turned off, but modem is functional

Test Amber

- Dark for initial self-test of the cable modem OK(*4) or power off
- Flashing for initial self-test of the cable modem in progress
- Solid for self-test failure of the cable modem (power recycle, and if light stays solid, need to swap modem)


(*1) Flashing slowly: flashing approximately every 2 seconds
(*2) Flashing: flashing approximately every 1 second
(*3) Flashing fast: flashing approximately every 0.1 second
(*4) It takes approximately 30 seconds to complete the self-test for the cable modem after power on. Then searching the downstream RF carrier will start.

Products

  • HyperNet

Resolution

What do the flashing lights on my cable modem mean?

Your cable modem has 5 lights (see the tables below). Three of them are solid green when your modem is functioning properly.  The two remaining lights (the TD and RD lights) will blink during normal operation. The TD light shows data coming from the cable modem network and the RD light shows data being sent by your cable modem out to the network.

These two lights will occasionally blink even if your computer is turned off. The network is checking with the cable modem to see if it has information to pass.  Following are couple of items to verify concerning your usage:

Categories

  • Internet/Cable Modem/Com21/Usage
  • Internet/Cable Modem/Docsis/Usage

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