The Realtek Remote Control Protocol (RRCP), developed by Realtek, is an Application layer protocol, running directly over an Ethernet frames. Main idea behind this protocol is to allow direct access to the Ethernet switch controller's internal register over an Ethernet network itself. This approach allows to avoid cost of including a processor, RAM, Flash memory, etc. in a managed Ethernet switch. Instead, all "intelligence" is targeted to reside in a nearby computer, running special RRCP-aware Ethernet switch management software.
Contents
Packet types
All packets are transmitted as Ethernet frames with EtherType 0x8899. Details on the RRCP protocol are listed in the datasheets of some chipsets with RRCP support: RTL8324BP and RTL8326.
Hello
Used to initiate scan for RRCP-capable switches in a network segment, and to fetch some their parameters.
Hello reply
Is sent by an RRCP-capable switch as a response to a valid "Hello" packet. Contains some their parameters, such as IDs, and MAC addresses.
Get
Used to fetch value from internal switch controller's register.
Get reply
Is sent by an RRCP-capable switch as a response to a valid "Get" packet. Contains requested register number and value, that was read from it.
Set
Used to set an internal switch controller's register to a certain value. Contains register number and a value to be written to register. No acknowledgment is generated by a switch.
Loop Detect packet
Is not a part of RRCP protocol itself, but is closely associated, being an underlying mechanism for a simplified Spanning tree protocol substitute in RRCP-capable switch controllers.
Echo request
Is not a part of RRCP protocol itself, but is closely associated, being an underlying mechanism for a Layer-2 analog of ICMP Echo request (Type 8) message in RRCP-capable switch controllers.
Echo reply
Is not a part of RRCP protocol itself, but is closely associated, being an underlying mechanism for a Layer-2 analog of ICMP Echo reply (Type 0) message in RRCP-capable switch controllers.
Hardware
Currently, RRCP protocol is officially working on Realtek's RTL8316BP, RTL8318P and RTL8324P switch controller chips. Unofficially, it also found to be working on RTL8316B, RTL8324, RTL8326 and RTL8326S.