[cmsigler]

Hi all,

First, thanks for a fantastic project. I'm doing volunteer support for a non-profit school I help. I've successfully used dd-wrt to turn inexpensive routers which I donated into repeater bridges.

My problem is with a Cisco/Linksys E2100L that was available as surplus. Specs FYI:

-- CPU Atheros 9130, Flash ROM 8 MB, RAM 64 MB, Radio 1x 2.4 GHz, WLAN Support B/G/N

This started as an experiment, but now I'm looking at it as a learning experience....

For this unit, I followed the model-specific page to the letter. My initial flash was successful using:

others/eko/BrainSlayer-V24-preSP2/2013/02-11-2013-r20675/linksys_E2100L/e2100l-firmware.bin

I had repeater bridge problems so after this initial flash I then flashed a newer firmware via web GUI using:

betas/2015/04-09-2015-r26653/linksys_E2100L/e2100l-firmware.bin

I got: "Upgrade successful. Unit is rebooting now. Please wait a moment..."

But came back up bricked! I swear I was careful. I didn't see any power glitches, all cables connected solidly, I waited 10 minutes just to be sure, etc. When it bricked, before I power cycled it the power light started flashing rapidly. Knew I was in trouble then. Not sure what happened *shrug* (I re-checked to make sure my ftp dl wasn't corrupted. It wasn't.)

Symptoms: Power up, power light immediately flashes rapidly. 8 secs. after power up, Ethernet lights 1-3 and the Internet light flash quickly two times. Ethernet port 4 works although its light is now dead (light had worked prior to bricking).

Ping & wireshark show a couple of interesting things:

1.) When pinging, never any replies, including at power up. When I power up with reset button on bottom pushed, still never a reply, no ttl=64, no ttl=100, nothing. (Bad news.)

2.) On wireshark, when pinging my laptop issues an ARP request to the E2100L (not a broadcast, it's sent directly to the E2100L's MAC address):

"Who has 192.168.1.1? Tell 192.168.1.10"

The E2100L *does*reply* directly to the laptop (fascinating) with:

"192.168.1.1 is at 68:7f:74:xx:xx:xx"

so *something* in the E2100L is able to reply to ARP correctly at some low level. (Is this purely in hardware?) But nothing else is seen in wireshark except ping requests to which there are no replies.

3.) When the power cord is pulled, the E2100L issues an ARP broadcast of:

"Who has 255.255.255.255? Tell 192.168.1.1"

(which I assume is something like spontaneous power drain noise...).

4.) Otherwise, the thing doesn't reply at all on any ports. Wasn't sure if Management Mode was possible, tried it anyway with absolutely no success.

So it's gotta be well and truly bricked. This is surplus, so maybe hardware was marginal before I picked it up and now it has failed(???). But the ARP reply with correct default IP address gives me faint hope.

I'm thinking about getting the USB to RS-232 TTL serial cable and cracking her open for soldering.

QUESTIONS:

1.) Does this mean that the bootloader is defective, or the firmware/kernel? I couldn't figure that out from the wiki because it seems in between cases 1 and 2 under "Recover from a Bad Flash." (Or does that not apply to Atheros?)

2.) Is it reasonable to try serial cable recovery?

3.) Should I JTAG instead (I'm a Linux user FWIW)?

4.) Do these symptoms appear fatal? Am I completely wasting my time?

TIA for any help or guidance you have time for

Clemmitt

[cmsigler]

Hi again,

Replying to myself to post the fix to recover from bricking my Cisco/Linksys E2100L.

When I went looking for help on opening up the case I found clear info and instructions via OpenWRT's page for the twin to this model, namely, the Linksys WRT160NL. I guess I was too dense and impatient to make sense of the abbreviated tftp instructions on the dd-wrt wiki page, "Recover from a Bad Flash."

More info here:

http://wiki.openwrt.org/toh/linksys/wrt160nl#unbricking_via_tftp

http://wiki.openwrt.org/doc/howto/generic.flashing.tftp#bootloader_contains_tftp_server

http://wiki.openwrt.org/doc/howto/generic.flashing.tftp#linuxbsd

Simple instructions (that even a novice can make use of :^) --

1.) Remove the power plug from the back of your bricked router, then connect the router (preferably port 1) with an Ethernet cable to a port on an Ethernet switch. The switch must be powered on.

2.) Connect your laptop/desktop to another port on the same Ethernet switch.

3.) The default IP address for the bricked E2100L is 192.168.1.1 (unless there's another problem). Choose a different address in the same subnet (i.e., 192.168.1.0/24) and assign that to your laptop's Ethernet port as a static address. (If you don't know how, Google is your friend for Windows, Mac OS or Linux.) A suitable address is 192.168.1.10 .

4.) Download a good firmware file and verify its integrity. I used the available E2100L FW from the Linksys site:

http://www.linksys.com/us/support-article?articleNum=148501

http://downloads.linksys.com/downloads/firmware/1224655367568/FW_E2100L_1.0.05.004_20120308_code.bin

5.) Copy the firmware file to a temporary storage folder, renaming FW_E2100L_1.0.05.004_20120308_code.bin to code.bin .

6.) On your laptop, start tftp client program to put the file named code.bin to IP address 192.168.1.1 using binary/octet transfer mode, with multiple retries. If this is Greek to you, read the above OpenWRT wiki pages as well as "Recover from a Bad Flash" on our dd-wrt wiki. They will explain in much more detail.

7.) Plug the power cord into the back of your bricked router.

8.) Be patient. If you run atftp from a console/command prompt with the verbose option, you'll see the file being uploaded block by block. You'll also see the data transfer if you run wireshark.

9.) Continue being patient! Allow the router MANY minutes to reset and reboot.

10.) After it has rebooted and the lights have more or less stopped blinking, try pinging 192.168.1.1 . The router should reply now.

11.) I had to reset the router's config/NVRAM. To do this, while it was powered up I pressed and held the reset button on the bottom for 5 secs., then the power light started flashing. I waited patiently for it to stop flashing, then logged into the web interface at IP address 192.168.1.1 with the default username/password.

Having recovered, I've now reflashed to dd-wrt firmware and am back to doing some testing, confident in the knowledge that should I brick it again I can unbrick it easily and start over

Clemmitt

[lazardo]

This post allowed unbricking another e2100L triggered by a bog standard dd-wrt upgrade as described earlier, except using a newer build rather than stock as intermediate step.

Fix: Power off, ethernet client up as 192.168.1.10/24 and connected to e2100L port 1, then start tftp, then power on.
The tftp packets could be seen on the client as ordinary ethernet traffic and the tftp beginning/end looked like this:

[philco782]

Thank you so much Lazardo.

I'm happy to have unbricked my E2100L with the above tftp commands. I would like to add that all of the Windows tftp clients I tried to use did not work.

What will work is installing Cygwin, and making sure you check install for the tftp client. This will give you the full unix tftp client that works verbatim with the above command script.

Thanks!

P.S. What caused my bricking apparently happened going from v31571 to v41379. I installed the stock Linksys firmware through tftp, and then I was able to directly install v41379 from the web interface, and so far so good! v41379 was the most recent version I was able to find another user successfully using during my hours of scrubbing the web