ServerNet Cluster 6780 Operations Guide (G06.29+, H06.06+, J06.03+)

ServerNet Cluster Software
ServerNet Cluster 6780 Operations Guide—525606-004
A-5
Expand-Over-ServerNet Line-Handler Processes
SNETMON Interaction With the Expand Line-Handler
Processes
SNETMON interacts with the Expand line-handler processes using the NAM protocol
to:
•
Enable Expand line-handler processes to synchronize with each other during
startup.
•
Enable detection that the remote Expand line-handler process is down.
•
Inform the appropriate local line-handler process when the ServerNet cluster
connection to a remote node goes down.
Expand-Over-ServerNet Line-Handler Processes
The Expand subsystem is the networking software that connects NonStop S-series
servers and other NonStop servers. It extends the operation of the fault-tolerant
NonStop Kernel operating system to dispersed nodes. Expand-over-ServerNet is a
communications medium for the Network Access Method (NAM). For more details on
the Expand subsystem, see the Expand Configuration and Management Manual.
The Expand-over-ServerNet line-handler processes manage security-related
messages and forward packets outside the ServerNet cluster. Secure message-system
traffic between processes on different ServerNet nodes travels through the Expand-
over-ServerNet line handlers and through the local message system between the
communicating processes and the line handlers. Nonsecure message-system traffic
flows directly between processors through the intersystem message-system ServerNet
connections as directed by the Network Routing Table (NRT) under the control of
Expand.
Expand-over-ServerNet lines are configured using the WAN subsystem.
Like the Expand-over-FOX line-handler process, each Expand-over-ServerNet line-
handler process can support only a single line and a single neighbor node. So the
Expand-over-FOX line-handler process and the Expand-over-ServerNet line-handler
process are always separate processes with different logical devices (LDEVs).
Note. Other messages, such as incoming and outgoing data, usually bypass the Expand-over-
ServerNet line-handler process and are handled directly by the ServerNet X fabric and Y fabric
and the message system. This behavior is known as Expand bypass mode.