Network switches come in two different flavors: managed, where you have some interface to configure and monitor the equipment, and unmanaged where the device just does what it is supposed to do and you can’t really control it. [Tiziano Bacocco] wanted to manage his cheap unmanaged switch, so he did what any good hacker would do: he opened it up.
Inside the Digicom 10/100 switch he found an IP178CH controller IC and a quick search turned up a data sheet. [Tiziano] noticed there were three ways to configure the switch: Some hardware pins could control very basic functions; an EEPROM (absent on the PCB) could configure the device; or the chip would accept commands via a synchronous serial port.
Since the datasheet covered the protocol required, [Tiziano] commandeered an Arduino Pro Mini and used it to send commands to configure the switch. A few resistors and some quick code allowed him to control VLAN and other functions on the switch via the USB port. Of course, he mentioned you could use a Raspberry Pi if you wanted a network interface–or maybe that’s a good excuse to use one of those Ethernet shields you got on clearance at Radio Shack.
Continue reading “Managing an Unmanaged Switch”
[Kenneth Finnegan’s] post about this 24-Port HP ProCurve 2824 Ethernet Switch teardown was a delight to read. He’s taking an introduction to networking class at California Polytechnic State University. One of their labs included virtual machines shooting thousands of new MAC addresses at the thing all at once. Despite it’s ability to switch data at a blazing fast rate, it’s ability to deal with that many new hardware identifiers was less than impressive. He wanted to find out why and it just so happened he had one of these in his parts bin at home (which he refers to as if it’s a high-powered RPG character).
The mainboard is divided into three major blocks: the power supply, the switching hardware, and the processor that makes this a manged switch. Although he covers all of these pieces (and the switching stuff is very interesting to learn about) it is the processor section that was causing the aforementioned slowdown. It’s a 266MHz PowerPC chip with a measly 64 MB of RAM. Of course this doesn’t need to be any more powerful since all traffic from previously ‘learned’ MAC addresses gets handled by the switching block and never touches the processor portion.
Don’t miss the end of his post where he discusses how the filtering caps, and semi-isolated ground planes help to tame the beast created from all of this high-speed switching.