Replacing an Ubiquiti EdgeRouter Lite 3 flash drive

Wow, it’s been a while since I’ve dropped by here. But it’s all worth it as I want to share my experience in replacing my Ubiquiti EdgeRouter Lite 3 flash drive. It has been a rather long journey, so I thought I’d share my experience.

I will not enter into all the technical details but here is a rough list of what I used. This was done on a laptop running with Ubuntu Bionic.

• A USB to RJ-45 console cable
• minicom with the suggested setup from the official doc (115200-8bits-No parity-1 stop)
• tftpd-hpa : the tftp server

Diagnostic

Coming back from my summer vacation, I found my ERL 3 no longer working. After trying the official documentation and seeing that no IP address was set on ports ETH0 / EHT1  as outlined in the doc, I elected to check the console port.

My first try gave me this :

For some reason, only garbage came out of the console port. An hour of googling lead me to believe that the USB console cable was the culprit. A colleague lent me another cable and I got this which was already much better :

At this point, I should have been a bit more attentive on the message displayed. I got distracted by the fact that some USB Device was seen by the firmware as seen in :

USB: (port 0) No USB devices found.
0

The next two lines clearly indicated that the firmware was not able to access the partitions on the flash drive :

** Partition 1 not valid on device 0 **

** Unable to use usb 0:1 for fatload **

Setting up the TFTP server

This is not the topic of this article, but in short, on Ubuntu you need to install the tftpd-hpa package and you are all set. The image files to be served by TFTP are to be copied in /var/lib/tftpboot.

Identifying the real problem

After some more googling, I found this very good article that, while not being specific on the flash drive replacement, explains very well how to use a TFTP server to load : Recovering an unresponsive Ubiquiti EdgeRouter Lite router. My own article uses portion of this post so I am very thankful to Darren Scott for writing this.

For me, the most useful instructions on this article is how to set the Ubiquiti firmware to be able to fetch a file using tftp. Remember that, so far, I have not been able to reach my router on the network. Even setting up my laptop nic with a 192.168.1.10 ip address did not let me reach the supposed 192.168.1.20 ip address configured on the ETH0 port of the router. I supposed that this is setup by the Ubiquiti firmware stored on the flash drive. Using the following commands, I was able to trigger a TFTP download from my laptop :

# set ipaddr 192.168.1.20
# set netmask 255.255.255.0
# set serverip 192.168.1.10
# set bootfile ER-e100.recovery.v2.0.6.5208553.190708.0607.16de5fdde.img.signed
# tftpboot

I tried his method using the ERLite-3 / ERPoE-5 (e100) image proposed in the official documentation but got the following :

Octeon ubnt_e100# set ipaddr 192.168.1.20
Octeon ubnt_e100# set netmask 255.255.255.0
Octeon ubnt_e100# set serverip 192.168.1.10
Octeon ubnt_e100# set bootfile ER-e100.recovery.v2.0.6.5208553.190708.0607.16de5fdde.img.signed
Octeon ubnt_e100# tftpboot
Interface 0 has 3 ports (RGMII)
Using octeth0 device
TFTP from server 192.168.1.10; our IP address is 192.168.1.20
Filename 'ER-e100.recovery.v2.0.6.5208553.190708.0607.16de5fdde.img.signed'.
Load address: 0x9f00000
Loading: octeth0: Up 1000 Mbps Full duplex (port 0)
#################################################################
#################################################################
#################################################################
#################################################################
#################################################################
#################################################################
#################################################################
#################################################################
#################################################################
#################################################################
######
89 MB received
#################################################################
#################################################################
########
done
Bytes transferred = 113549500 (6c4a0bc hex), 7316 Kbytes/sec
WARNING: Data loaded outside of the reserved load area, memory corruption may occur.
WARNING: Please refer to the bootloader memory map documentation for more information.

The indication WARNING: Data loaded outside of the reserved load area, memory corruption may occur. Made me think that the image was too big to fit in the boot memory section. So this was not the solution.

Finding the EdgeMax Rescue Kit

Darren Scott’s blog post refers to another Ubiquiti Community post called EdgeMax rescue kit (EMRK). This is the kit used to reset the router in Darren’s article. Unfortunately, the links given to download EMRK are all dead. After some research, I was able to locate this EMRK download link : https://downloads.vyos.io/?dir=tools/emrk/0.9c. Let’s home that is remains available.

Replacing the flash drive

Reinstalling Ubiquiti firmware

Once this is completed you can reboot your Ubiquiti EdgeRouter Lite 3. After the boot sequence you should see the well known :

Welcome to EdgeOS ubnt ttyS0

By logging in, accessing, or using the Ubiquiti product, you
acknowledge that you have read and understood the Ubiquiti
License Agreement (available in the Web UI at, by default,
http://192.168.1.1) and agree to be bound by its terms.

ubnt login:

Voilà !