Adventures with Tomato Firmware and Sierra Wireless MC8700

busted_power_adapterI got call from parents that their broadband connection have stopped working. I was sure that it’s like all the other times and it just needed to be rebooted because of problems with connection and/or software or factory reset because of shitty software. After I arrived it turned out that power adapter of the 3G MicroRouter (“USB to Ethernet adapter”) was busted.

I found my old universal power adapter from closet so I tried with that. LEDs turned on and everything looked good for 15 minutes and then the device itself burned. So what now? We have ADSL connection as second (“emergency”) connection, but that’s like really slow. Well, at least I can google for solution.

busted_siptune_microrouter

I noticed that it’s possible to remove the need of MicroRouter by flashing custom firmware to Asus WL-500GP V2 router if 3G modem we have is supported (Siptune SM-215). It was easy to find out that it’s actually USB-adapter for Sierra Wireless MC8700.

First I tried DD-WRT, but found out quite fast that there was no version for this router that supports broadband easily out of the box. My next try was Tomato by Shibby.  I had no idea if it would work with MC8700 and I only found some forum posts about how it didn’t work, I still tried because those posts were quite old.

I hoped to get easy so I just downloaded Mega version (tomato-K26USB-1.28.RT-MIPSR1-132-Mega-VPN) and found out that there was not enough memory for this one on this router. After that I looked how the images were named (http://tomato.groov.pl/?page_id=66), found out that English page was work in progress and used translator just to notice the note to look in to builds.png image. No idea where that is because it was not a link and it’s not in screenshots either, so I had to google for it. It turned out the latest smallest version for this router with USB-support is one with VPN (tomato-K26USB-1.28.RT-MIPSR1-132-VPN). It worked, now I just need to setup the 3G modem, that looked easy, just choose right tty device from the list… except no idea which one the modem is.
So I decided to look in to logs and search by word “sierra”.

Jan 1 01:00:19 unknown user.info kernel: drivers/usb/serial/usb-serial.c: USB Serial support registered for Sierra USB modem
Jan 1 01:00:19 unknown user.info kernel: sierra 1-1.1:1.0: Sierra USB modem converter detected
Jan 1 01:00:19 unknown user.info kernel: usb 1-1.1: Sierra USB modem converter now attached to ttyUSB0
Jan 1 01:00:19 unknown user.info kernel: sierra 1-1.1:1.1: Sierra USB modem converter detected
Jan 1 01:00:19 unknown user.info kernel: usb 1-1.1: Sierra USB modem converter now attached to ttyUSB1
Jan 1 01:00:19 unknown user.info kernel: sierra 1-1.1:1.3: Sierra USB modem converter detected
Jan 1 01:00:19 unknown user.info kernel: usb 1-1.1: Sierra USB modem converter now attached to ttyUSB2
Jan 1 01:00:19 unknown user.info kernel: sierra 1-1.1:1.4: Sierra USB modem converter detected
Jan 1 01:00:19 unknown user.info kernel: usb 1-1.1: Sierra USB modem converter now attached to ttyUSB3
Jan 1 01:00:19 unknown user.info kernel: usbcore: registered new interface driver sierra
Jan 1 01:00:19 unknown user.info kernel: drivers/usb/serial/sierra.c: USB Driver for Sierra Wireless USB modems: v.1.7.0
Jan 1 01:00:21 unknown user.notice root: 3G MODEM ready – using sierra module 

Okay… device is ttyUSB 0 1 2 and 3?!

By trial and error I found out that the right choise is /dev/ttyUSB3
Connecting to network is slow by the way. I was not patient enough on the first try (almost gave up) so just wait for couple of minutes when it’s connecting.

MC8700_tomato
I Also tried to google about ping and how to make things works smoother and turns I could optimize MTU size since 1500 produced errors. Right MTU size for this connection is 1472. https://bbs.archlinux.org/viewtopic.php?pid=835033#p835033

ping -c 1 -M do -s 1500 http://www.google.com
PING http://www.google.com (216.58.213.164) 1500(1528) bytes of data.
ping: local error: Message too long, mtu=1500

http://www.google.com ping statistics —
1 packets transmitted, 0 received, +1 errors, 100% packet loss, time 0ms

 

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