NonStop NS-Series Planning Guide (H06.03+)

ServerNet Communications Network
HP Integrity NonStop NS-Series Planning Guide—529567-004
3-2
Concurrent Messages
fabric and the Y fabric, together provide a fault-tolerant interconnection for the
ServerNet network.
Each processor complex connects to both fabrics with ServerNet adapters also
connecting to both fabrics. The X fabric and the Y fabric are independent and
therefore, are not connected to each other. Communications occurring on one
ServerNet fabric cannot cross over to the other ServerNet fabric.
Concurrent Messages
The ServerNet communications network allows many messages to be sent
concurrently.
Processors and I/O devices communicate over point-to-point ServerNet links
connected by ServerNet routers, which are crossbar switches that can simultaneously
connect any input with any output.
Interconnected Components
The ServerNet communications network allows numerous connections among many
types of system components. Because each ServerNet link is point-to-point, different
ServerNet links can be in use simultaneously with different messages.
For example, logical processor 0 might receive two kinds of messages simultaneously:
data from an I/O device and messages from another processor.
This structure allows you to transfer data directly between any two components on the
ServerNet communications network.
Fault Tolerance for Complex Operations
The ServerNet architecture extends fault tolerance to operations that previously
required a system outage. You can add, online, not only individual components but
also entire enclosures. To add modular components online, see the NonStop NS-
Series System Expansion and Reduction Guide.
ServerNet Communications Network
This subsection illustrates the ServerNet communications network in each of the major
enclosures. The ServerNet architecture uses two redundant networks with the
hardware resources of the processors, storage devices, and communications adapters
arranged in a star configuration around a functional pair of hubs: the p-switches and
the ServerNet switch boards in each IOAM enclosure.