SM-Ethernet User Guide
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4.8.5
VPN
A VPN (
Virtual Private Network
) is a method of using a non-secure or public network
that allows devices to be connected together as if they were connected on a private
network. A typical example would be the connection of two remote offices such as
London and New York. Each office would require a high speed Internet connection and
a firewall (
or VPN device
). In order to configure the VPN, encryption keys are
exchanged so that both offices can communicate. The data is then sent across the
Internet (
or shared network
) in an encrypted form, giving the illusion of a single
connected network (
speed limitations may apply
). This is generally used as a low-cost
alternative to a private leased line. Configuration of VPNs is beyond the scope of the
document.
4.9
Typical network connections
4.9.1
Single PC to SM-Ethernet
To connect a PC to the SM-Ethernet using the default setting of Pr
MM.43
requires a
crossover cable. This allows the two devices to communicate without the need to
change any settings on SM-Ethernet or the use of a switch or hub.
Figure 4-3 Connecting a single PC to SM-Ethernet using a crossover cable
When purchasing network cables it is recommended that a different color (
e.g. pink
) is
used for crossover cables to allow easy recognition. When connecting as in Figure 4-3,
to avoid the need for crossover cables it is possible to change the SM-Ethernet RJ45 port
to use a non-crossover cable by setting Pr
MM.43
to 1. This will force SM-Ethernet to
detect the type of cable used when it initialises allowing either type to be used. If auto-
detect is disabled (Pr
MM.43
=0) a cross-over cable is needed or you need to connect via
a switch. For more information see
SM-Ethernet enable auto-crossover detection
cross over cable
NOTE
Some PCs and network switches provide auto-crossover correction and therefore the
need for a crossover cable may not be necessary. Refer to the PC or network switch
documentation for confirmation.
NOTE
Summary of Contents for SM-Ethernet
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