Maybe we have been unlucky, but the DLink DSL-2680 seems to have a short lifespan. We've got through three of the devices in less than six months.
A crashed DSL-2680 router completely freezes and loses all external connectivity. Port scanning it from the LAN side reveals the presence of an ethernet device, but all the TCP/UDP sockets that are normally listening are shown as filtered.
However, even in the 'crashed' state, a serial cable connected to the UART pins on the mainboard will get you to the shell of the ZyNOS BootBase bootloader.
From the shell, I've done extensive DRAM memory testing (all tests passed 100%) and I have checksummed the contents of the 2MByte SPI flash memory from a crashed DSL-2680. The flash memory from a failed device compares byte-perfect against a known good flash.
So those tests vindicate both the DRAM and the flash memory. Since the CPU continue to work correctly, I would guess that the fault is with the ADSL analog front end (AFE). Maybe it is particularly susceptible to damage from adverse line conditions.
It is a shame that the DSL-2680 falls down so easily because it is an otherwise competent device with comparatively high line synchronisation speeds.
The technical specs of the DSL-2680 are as follows (1).
- TrendChip TC3162U ADSL2+ Router/Processor. This has an ARM7/ARM9 core clocked at 192/200 MHz (2)(3)
- TrendChip TC3086 ADSL2+ Analog Front End (AFE) (4)
- 2 MByte serial flash memory (1x Winbond W25Q16BC). The flash supports quad SPI (four bits banged out simultaneously) but this is disabled in the firmware) (5)
- 16 MByte SDRAM (1x ESMT M12L128168A) (6)
- 802.11n WLAN driver (1 x Ralink RT3390) interfaced to the TC3162 via the PCIe bus, and using the RT3090 driver (7)
- 10/100 MBps Ethernet switch (1 x Ralink TC2206) (8)
- ZyNOS BootBase v. VTC_SPI1.6 (bootloader with SPI flash support, and ZyXEL BootExtension) (9)(10)
- HTP_TC v 0.05 (Hardware Test Program, disabled)
- RAS v.1.08 (ZyXEL Router Application Software)
Edited by asbokid (Sun 26-Jun-11 14:39:11)