getting a TpLink Switch back to life

[pepe]

Hello folks,

long story short: i need an arbitrary config backup for a TL-SG3424 switch, if anybody uses this model, i would be grateful for a config file.

long story long:

my TpLink switch (TL-SG3424) packed up yesterday and i spent some time analyzing it a bit with the following results:
- the initial problem was that the first 16 ports are completely dead, ports 17-24 showed some signs of life at least. System LED remains off (it should be blinking normally).
- supply voltages are fine, stable, not a dried out caps issue
- i got a serial port attached to it and checked what it spits out there. It wasn't much, initially it just displayed a msg to press ctrl-B to enter bootUtil and a word about starting the fw
- i entered boot util and found there are some commands to reset config and update fw.
- first i tried resetting config and it failed in a similar way as this: https://community.spiceworks.com/topic/2287393-tp-link-tl-sg3424-factory-reset-problem
- i also downloaded various FW versions from tplink site and updated the fw through ftp. This was done through port 1, so the initial deadness of these ports is probably due to lack of config, not a hw problem.
- tried to attach jtagulator to its jtag port, which seemed the easiest way of detecting if that port is alive. The pcb layout matches pretty well with MIPS EJTAG connector pinout btw : http://www.t-es-t.hu/download/mips/md00047f.pdf
- jtagulator found nothing, which means to me that the port is disabled in some way.
- I tested jtagulator with a TL-WR1043ND, which has the same jtag layout albeit for a through hole connector. This worked OK, the pinout was identified correctly, matching the linked document.
- i removed the heat sink, which revealed a BCM53314 MCU and some more resistors but could not identify anything that would have enabled the JTAG port.
- i found a way to help it through its main problem by shorting certain flash pins at certain moment, so the fw starts up, but the config was pretty much missing (IP address was unconfigured, interfaces too and a couple of other things).
- I did an initial config to set up ip address to be able to transfer config to a pc and back. The config file i got is pretty weak, it had 4094 dummy VLAN entries and some for the ports but that was more or less everything it had. I removed the vlan entries and downloaded it back to the switch, which helped it init faster but still needing my gestures with the tweezer

- at this point i would be really curious to see a working config file and compare, if anybody could send me one. It can be backed up from the web interface as well, no need to mess with the CLI if one's feeling uncomfortable with it.
- also interested in getting that jtag port working... but i believe this is gonna be a bit harder.

thanks a bunch,
pepe

[einstein9]

pepe, have you tried the Console Cable? RS-232 to eth (image attached)

with this cable you will be able to access the device booting and start repairing the unit

Note: some devices such as Cisco are using special pin parameters, not sure about the TP-Link

Attachments

[pepe]

i hooked up a n usb-ttl serial adapter to behind the ttl-rs232 converter (similar to MAX232) and did the above hacking through that. Almost the same as your cable, just a bit more simple (to me, in this situation, when the pcb is unmounted from the chassis).

pepe

[einstein9]

what kind of config you are looking for? the default switch you mean?

[pepe]

there is an option to back up current config on a working switch, i need such a config backup file. coz the factory reset does not restore mine in a usable state, in fact, i think the factory config is damaged/erased/corrupt.

Nobody uses this model of switch?

pepe

[sin]

Wouldn't a full firmware restore do?
Does DDWRT has anything with the kind of switch you have?

--

[HaQue]

I would be worried the backup config in the factory restore is not the only thing damaged.
If a full firmware flash doesn't change it, then If you love that switch model:

eBay.com.au
USD 129.99 + tax

or get any other GB switch

I only have enterprise HP, Dell, Brocade and Cisco switches here. All My TP-Link ones are small 5, 8 and 16 port SOHO ones. So I cant say if yours support a full flash over tftp or not

This could be a faulty flash chip, or some other small PCB issue that is causeing these problems. Really not worth the time IMHO

[pepe]

of course it does not worth the time, however, it would worth a shot with a working config or at least to see what's in there to begin with...
5 minutes to pull it from a working one and similar amount of time to download to this one and see if it does anything good...
Just out of interest...
I was almost sure in such a large community somebody would be able to send it but apparently this is beyond imagination. Not even on tplink forum. Kind of unbelieveable to me

pepe

[HaQue]

likely the people reading this just don't have those switches. Not a very popular switch, likely other brands would be used for a switch of that feature set... plus the age of the switch.

I asked a group of EDU techs if any have that model switch, and if they could supply a config.

I'm wondering if the flash is faulty, as if you said it would init after shorting, then possibly it is going to the 2nd copy of the fw. If the TP-Link does what others, like Brocade, they keep a Primary and a Secondary copy of the firmware. If PRI fails, it will try and boot the Secondary. If flash is damaged/corrupt, this can get past it at times.

It is sounding more like this scenario to me.

[pepe]

Hi HaQue,

thx for your efforts!

I think it was a corruption initially, which probably got rectified by some of the fw update, coz i did not get the read error message lately. However, reset command does not have effect, if i export the config after reset, it is kind of crap, has about 4k+ VLANS defined, and not much else. As if an empty flash page was used as config.
I don't argue with it being not very popular, but high numbers would say there should be some of these laying around somewhere
I would have expected higher activity at the TPlink forum, strange.

pepe

[HaQue]

Well no-one came back with anything for this model, sorry about that.

I remember TP-Link have a web emulator for a lot of products. not sure if you would be able to get a config from there, but I have been able to get up to speed on unfamiliar hardware using emulators, before some jobs.

https://www.tp-link.com/us/support/emulator/
https://emulator.tp-link.com/TL-SG3424/Index.htm

But yours is displaying classic symptoms of a hardware fault, IMO.

[pepe]

i already tried the emulator, without success, now checked how it fails, it simply says config saved but no way to select the location...

pepe

[HaQue]

I think The save config saves current config to the flash memory.
the part to save it to HDD is system->system tools->config backup. but it doesn't work unfortunately likely did not setup emulator to have file I/O