UFiber GPON - How to Recover OLT


In this article we will provide the necessary steps to recover a UFiber OLT. This process will completely restore the OLT to factory default settings and erase all settings.

The recovery image is different than the OLT firmware update download. It can be found the here.
Devices used in this article:
  • USB Console Cable
  • UFiber OLT

Table of Contents

  1. Introduction
  2. How to Recover OLT
  3. Related Articles


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In rare cases when an OLT becomes unresponsive, these instructions may be suggested by our support team to recover the OLT back to its default state. This is typically not the first step in troubleshooting issues, but rather a last resort recovery method.

How to Recover OLT

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1. Connect to OLT with Console

Using a USB to serial cable, connect to the OLT Console port and your computer.

Using OS X:

1.1. Open Terminal Application in OS X

1.2. Find your serial interface

ls -ltr /dev/*usb*

The serial interface will show ".tty"  here is an example:

mac:~ admin$ ls -ltr /dev/*usb*
crw-rw-rw-  1 root  wheel   21,   3 Feb  8 15:48 /dev/cu.usbserial-AI038TPF
crw-rw-rw-  1 root  wheel   21,   2 Feb  9 08:56 /dev/tty.usbserial-AI038TPF

1.3. Use Screen command to connect to console.

Type screen and copy and paste the path to the serial interface.

screen /dev/tty.usbserial-AI038TPF 57600

Leave this window open, we will use this in again in step 4.1.

ATTENTION: Each serial interface will be unique, do not copy the command above exactly. Replace /dev/tty.usbserial-AI038TPF with the value given when using 
ls -ltr /dev/*usb*


NOTE: The baud rate for the OLT console interface is 57600 as show in the above command, other devices may have different baud rates.

2. Set up TFTP server on OS X.

2.1. Open a new terminal window

2.2. Load and Start TFTP Service.

sudo launchctl load -F /System/Library/LaunchDaemons/tftp.plist 
sudo launchctl start com.apple.tftpd

2.3. Set File Permissions.

sudo launchctl load -F /System/Library/LaunchDaemons/tftp.plist 
sudo launchctl start com.apple.tftpd

2.4. Set file permissions for the default tftp folder and other folders inside that folder.

sudo chmod 777 /private/tftpboot
sudo chmod 777 /private/tftpboot/*

2.5. Download the latest OLT recovery file from the UFiber downloads page.

2.6. Move OLT recovery image file to /private/tftpboot/

2.6.1. Click on Finder in OS X

2.6.2. Click Go in the toolbar and select "Go to Folder"

2.6.3. Enter /private/tftpboot/

2.6.4. Drag the OLT recovery .img fild to this /private/tftpboot/ folder

3. Connect to Management port

Physically connect your computer's Ethernet interface to the Management port on the OLT.

Set your computer IP address to manual with an address of and a subnet mask of

4. Reboot OLT

From the console terminal window opened in step 1:

4.1. Log into OLT using your credentials. (ubnt/ubnt by default)

4.2. Issue the reboot command Hold down the 1 (number one) key as the OLT reboots. 


4.3. When holding the 1 key, the OLT bootloader will be interrupted and bring you to a prompt like the one below. 

Please choose the operation: 
1: Load system code to SDRAM via TFTP.
2: Load system code then write to Flash via TFTP.
3: Boot system code via Flash (default).
4: Entr boot command line interface.
7: Load Boot Loader code then write to Flash via Serial.
9: Load Boot Loader code then write to Flash via TFTP.
default: 3

4.4. Enter the required IPs and filename recovery information

Enter IP of OLT

Enter IP of Computer

Enter image file name of the OLT image placed in the private/tftpboot/


1: System Load Linux to SDRAM via TFTP. 
Please Input new ones /or Ctrl-C to discard
Input device IP ( ==:
Input server IP ( ==:
Input Linux Kernel filename (vme600) ==:OLT.recovery.

After entering the recovery image file name and pressing the enter key, the OLT will scroll though showing "#" many times as it it loads the file to the OLT. This is expected behavior. Next the OLT will the remove and re-install the image, then reboot. As this occurs, you will also notice the fans speed may run at full speed until the the reboot and startup completes.

A successful recovery will allow management access using the console session established in Step 1 of this guide as well as GUI or SSH access at the default IP address.

Related Articles

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UFiber GPON - Getting Started

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