ServerNet Cluster Manual

ServerNet Cluster Description
ServerNet Cluster Manual—520575-003
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Node-Numbering Agent (NNA) FPGA
The NNA FPGA controls ServerNet addressing on the external ServerNet fabrics. The
FPGA contains circuitry that modifies the SID or the DID of each packet so the packets
are routed correctly between each node.
Note. The NNA FPGA modifies only one of the fields (DID or SID) and the CRC checksum of
each packet. The ServerNet address and data payload fields are not modified.
Figure 1-12. ServerNet Packet and ServerNet ID
H A D C
Key
A = 4-Byte ServerNet Address
D = 0-Byte to 64-Byte Data
C = 4-Byte Cyclic Redundancy Check (CRC) Code
ServerNet Packet
ServerNet ID
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Bits
ServerNet
Node
Routing ID
VST040.vsd
1-Bit Acknowledge/Negative Acknowledge/Negative Acknowledge
H = 8-Byte Header
20-Bit Destination ServerNet ID (DID)
20-Bit Source ServerNet ID (SID)
4-Bit Transaction Type
8-Bit Data Length
4-Bit Transaction ID
1-Bit Primary/Alternate Path
1-Bit Request/Response
5 Bits Reserved