Expand Configuration and Management Manual (G06.24+)

Expand Configuration and Management Manual—523347-008
3-1
3 Planning a Network Design
This section describes the network design decisions you must make before installing
and configuring a new Expand network or when modifying an existing Expand network.
Topics described in this section include
•
Selecting Line Protocols on page 3-1
•
Defining Paths Between Systems on page 3-7
•
Selecting Special Features on page 3-12
•
Designing the Network Topology on page 3-13
•
Creating a Network Diagram on page 3-16
Selecting Line Protocols
The Expand subsystem supports a variety of different protocols and communications
methods to enable you to connect systems in local area network (LAN) or wide area
network (WAN) topologies. This subsection discusses the advantages and
disadvantages of each of the protocols and communications methods supported by the
Expand subsystem.
Dedicated Lines
The direct-connect line-handler process implements the High-level Data Link (HDLC)
protocol and operates with conventional voice-grade leased-line and switched-line
facilities, private facilities, and fractional Transmission Group 1 (T1) facilities.
The major benefits of dedicated lines are
•
Performance. Dedicated lines can be permanently allocated by the telephone
network or carrier and can be conditioned to support fast, reliable data
communications.
•
Fault-tolerance. You can use the Expand multi-line path feature to enhance the
reliability of dedicated lines. Using this feature, you can configure up to eight
parallel lines between nodes. You should avoid using channels on the same
multiplexer for lines in a multi-line path between two nodes.
The major disadvantage of dedicated lines is inflexibility. When a dedicated line is
leased, it can only be altered by prior arrangement with the telephone company.
Note. This section is intended to help you make some basic design decisions; it is not meant
to be a comprehensive network design guide. You should consult your HP representative for
more detailed design information.