Guralp Systems CMG-DCM build <10,000 - Manual (Page 159)

Operator's Guide
If the GSL-EAM has multiple network addresses, you can limit the GDI
link receiver to use only one of them by entering it in the “Local IP
address” field. If left blank, the receiver will listen on all configured
addresses.
The default GDI link port is 1566 but this can be over-ridden if desired
- you would want to do this if you had multiple instances running on
the same address - by entering a port name or number in the “Local
port/service” field.
Backfill is the process whereby missing data is recovered. It can be
disabled if desired but, in most cases, you should leave this enabled.
The remainder of the screen contains a table within which you can
configure the GDI link servers to which this receiver should listen.
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