Guralp Systems CMG-DCM build <10,000 - Manual (Page 161)

Operator's Guide
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12.2 Güralp Secure TCP Multiplexer
The Güralp Secure TCP Multiplexer (GSTM) is a method by which
TCP and UDP connections can be tunnelled in both directions over a
single TCP connection. It is an essential tool in situations where local
network service providers cannot provide fixed (static) IP addresses.
For example, in an installation involving a single, central data
collection point and multiple, remote sensor sites it is sometimes
impractical for the sensor sites to be allocated static IP addresses.
Using GSTM allows the remote sites to initiate a single GSTM TCP
connection to the central site. Once established, further TCP and UDP
connections can be initiated in either direction: their packets are
tunnelled over the GSTM link.
If no sites in an array can be assigned fixed IPs, including the central
data collection point, a GSL-EAM or GSL-NAM can be installed
anywhere that has a fixed IP address and used as a communications
hub. All sites initiate GSTM connections to the hub, which can then
act as a communications router, forwarding individual connections as
required.
The initial link is established from a GSTM client to a GSTM server.
12.2.1 The GSTM Client
To set up a GSTM client on the CMG-EAM, connect to the CMG-EAM
configuration system via web or terminal. From the main screen select
“Services”, then “Guralp secure TCP multiplexor client”. The next
screen shows a list of all GSTM client instances that have been
configured on the CMG-EAM.
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