Space Wire Protocol ID Steve Parkes Space Technology

Space. Wire Protocol ID Steve Parkes Space Technology Centre University of Dundee Scotland, UK

Aim § The protocol identification scheme aims to § allow different protocols to operate concurrently over a Space. Wire network § without them interfering with each other § To achieve this an identifier is given to each protocol § Units receiving packets process and respond to them § according to the protocol specified by the protocol identifier on the packet. Parkes 2 MAPLD 2006 222

Logical Address Logical Protocol Address ID Logical Address with Protocol ID Path Logical Protocol Address ID Path Address with Protocol ID Parkes § Logical Address always used § After path address removed logical address is present § Check that packet is intended for the node it arrived at § Use 254 if node does not have a logical address 3 MAPLD 2006 222

Space. Wire Protocol Identifier Logical Address Protocol ID EOP Rest of Packet Logical Address with Protocol ID Path Address Logical Address Protocol ID Rest of Packet EOP Path Address with Protocol ID Path Address Parkes Path Address Logical Address Protocol ID 4 Rest of Packet EOP MAPLD 2006 222

Protocol Identifier § Protocol identifier (PID) § § Parkes single byte immediately following logical address PID value of zero reserved for protocol ID extension PID value of 255 is reserved 5 MAPLD 2006 222

Protocol Identifier § PIDs in range 1 to 239 assigned by the Space. Wire working group § § Parkes PIDs 1 upwards for recommended protocols PIDs 239 downwards for supported legacy protocols PIDs 1 -239 guaranteed not to clash i. e. each supported protocol has a unique PID 6 MAPLD 2006 222

Protocol Identifier § PIDs in the range 240 to 254 § available for experimental use § might clash with protocols being developed by other users § Concurrent operation of different protocols only assured for protocols in the range 1 to 239 § Proven protocols may be recommended for adoption by the Space. Wire working group § Once adopted § given unique protocol identifier in the range 1 to 239 § added to Space. Wire standard Parkes 7 MAPLD 2006 222

Ignoring unknown protocols § If packet arrives at destination with PID that is not supported (unknown) by that destination § Destination shall ignore the packet and delete it. § Count of the number of packets with unknown PIDs should be kept and made available by the destination. Parkes 8 MAPLD 2006 222

Extended Protocol Identifier Logical Address 0 Extn PID Logical Address with Extended Protocol ID Logical Path Address 0 Extn PID Path Address with Extended Protocol ID § § Parkes § PID with value zero (00 h) used to extend number of available PIDs Two more bytes follow reserved zero PID Forming a 16 -bit extended protocol identifier Allows up to 65535 protocols to be carried over a Space. Wire network Unlikely that extended PID will be used 9 MAPLD 2006 222

Extended Protocol Identifier § § § Parkes Implementation of the extended protocol identifier NOT mandatory If extended protocol identifier not implement then reception of a PID of value zero shall be ignored destination should record count of the number of packets it received with an extended PID Extended PID with value 000000 h is reserved and shall be ignored when received. 10 MAPLD 2006 222

Extended Protocol Identifier § Extended PIDs with values in range 000001 h 0000 FFh § represent same protocols as non-extended PIDs § with values 01 h to 0 FFh respectively § e. g. protocol 02 h is the same as protocol 000002 h. § Extended protocols 000001 h-0000 FFh are reserved § one byte IDs are used for these protocols Parkes 11 MAPLD 2006 222

Existing Protocols § Recommended § 1: Remote Memory Access Protocol (RMAP) § 2: Space. Wire working group working on reliable transport protocol § Legacy § 239: STUP for SMCS-332 ASIC configuration § 238: Proposal for RDDP Parkes 12 MAPLD 2006 222