ServerNet Cluster 6780 Planning and Installation Guide (G06.28+, H06.05+)

Table Of Contents
Planning for Installation and Migration
ServerNet Cluster 6780 Planning and Installation Guide527301-005
3-20
Task 10: Plan the Expand-Over-ServerNet Lines
Plan for Compatibility With Other Expand Lines
Nodes in a ServerNet cluster coexist as systems belonging to an Expand network.
ServerNet clusters are compatible with other Expand lines supported for that system
such as ATM, Ethernet, Fast Ethernet, FOX, Token Ring, and other LAN or WAN lines.
For example, a NonStop S-series server can simultaneously function as a node in a
FOX ring and a node in a ServerNet cluster. Using different hardware components to
route the packets provides physical coexistence:
Logical coexistence of the ServerNet cluster subsystem and the ServerNet/FX adapter
subsystem is provided by using different line-handler processes (Expand-over-
ServerNet versus Expand-over-FOX) to handle incoming and outgoing Expand
messages and packets.
Expand Time Factors
Expand Time Factors (TFs) are numbers assigned to a line, and reported for a path
and a route. $NCP uses TFs to make routing decisions to ensure that a message gets
to its destination in the most efficient way possible. $NCP determines the best-path
route based on the time factors (TFs) and hop counts (HCs) of available routes.
Although $NCP might be aware of several routes to a destination node, only a single
route is active at any one time. This single route, which is the most efficient route at a
given point in time, is called the best-path route.
Table 3-13. Number of Line-Handler Processes Required
Number of
ServerNet
Nodes
Number of Expand-Over-
ServerNet Line-Handler
Processes for Each Node
Total Number of Expand-Over-ServerNet
Line-Handler Processes
16 15 240
24 23 552
32 31 992
48 47 2256
64 63 4032
72 71 5112
96 95 9120
Note. ServerNet cluster technology permits a wide variety of Expand network topologies to be
constructed. To find out which topologies have been tested and approved, contact your service
provider.
FOX nodes ServerNet/FX adapters and fiber-optic cable for routing
ServerNet nodes Cluster switches, and fiber-optic cable for routing