This HOW-TO describes method of enabling RRCP protocol on switches, that contains RRCP-capable switch controller (i.e. RTL8316B, RTL8318P, RTL8324, RTL8326 or RTL8326S), but RRCP protocol does not work out-of-the-box.
4. Solder it in place.
Some switches (like D-Link DES-1024D and Compex SXP1224B) already have EEPROM soldered and RRCP enabled, but contains original Realtek crap (52:54:4С:01:02:03) instead of normal MAC-adrress, so using such devices in production is impossible (you can have no more than one device in L2-segment). The original solution was to desolder EEPROM chip, program it with appropriate data and solder it back (like in method 1). But there is much simpler solution: EEPROM write-enabling
Pin 7 (“WP”) of 24C02 EEPROM chip is responsible for write-protecting it. Chip can be writen, if this pin is logic-low (voltage is near GND level). If pin 7 is logic-high (voltage near VCC level), chip is write-protected. I.e. D-Link DES-1024D's 24C02 has this pin in logic-high level due to R5 resistor tieing it to VCC (see picture):
Note, that Pin 7 contains no internal pull-up inside chip, thus, when pin is floating it reads low level. So, to write-enable EEPROM chip, we need to solder off R5 resistor. You may even simply (carefully!) destroy R5, if can't desolder small parts.
This method is for switches, containing no place for EEPROM chip. RTL83xx chips supports one more method of cofiguring (pin-strapping). To use this method, you need to solder in resistor (470 Ohm to 10kOhm) beetwen appropriate pin(s) and ground (power) plane (details is chip-dependent).
Note, that this method implies a 2 serious limitations:
1) Switch will have no MAC adderess (it will have 00:00:00:00:00:00 as MAC address to be exact) - and as you guess, you can't have more than one such switch in a network. Moreover, some “smart” switches (at least, 3COM's 3c1100/3c3300) tend to filter out ethernet frames with 00:00:00:00:00:00 as destination MAC address, and you will never reach your RRCP-enabled-by-pinstrap switch if such “smart” switch is in the middle.
2) No configuration is saved permanently - you need to constantly (maybe one time per minute - from crontab) reconfigure such switch in order to survive switch reboot seamlessly
Pin 121(EnRRCP) is used in RTL8316B to preconfigure RRCP protocol enabled. You need to pull-up this pin to enable RRCP (i.e. solder in resisior beetween pin 121 and power-plane - VCC). Neareset pins, connected to VCC are 114 and 128. Note, that Pin 121 is also used as output for port 5, so do not try to connect it to VCC directly - you will burn port 5.
Pin 35(DisRRCP) is used in RTL8326/RTL8326S to preconfigure RRCP protocol enabled. You need to pull-down this pin to enable RRCP (i.e. solder in resisior beetween pin 35 and ground-plane - GND). Neareset pin, connected to GND is 34. Note, that Pin 35 is also used as output for port 10, so do not try to connect it to GND directly - you will burn port 10.