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EtherLite Concurrent Connections EtherLite Concurrent Connections
Symptom:
How many concurrent connections can be made on the
EtherLite?
Solution:
While most of our EtherLite products support up to 6
concurrent "host" connections, those connections do not have to be
from hosts running the same operating system. They can be a mixture of hosts
running any of our supported operating systems.
Keep in mind that we are being careful to differentiate
between sharing PORTS and sharing UNITS. While UNITS can be shared, PORTS may
not!
If more than one host attempts to open one of the serial
ports at the same time, the open will succeed for the first host there. The
other hosts will simply see an open failure (no lost data or damage, just a
failed open attempt). When sharing a single EtherLite between multiple hosts,
the administrator must simply make sure not to configure more than one host to
try and use the same port unless carefully managed between the hosts, based on
knowledge of each other.
The only requirements for a host to successfully make a
connection to an EtherLite are:
- There must be bootp/DHCP services on the (sub)net
where the EtherLite exists, and it does NOT have to be one of the
hosts running our driver.
- The host must have our driver loaded and have TCP/IP
access to the EtherLite.
- The host must NOT be the one which exceeds the
"concurrent host connection" limit for the EtherLite (See NOTES
below).
If a host attempts to make a connection to an EtherLite
which is out of available connections, that connection will simply fail. The
driver will assume the unit is "offline", failing, or powered off, and
automatically start retrying until the connection is established. If the
connection takes minutes without succeeding, an error will be passed back to the
application.
Exceeding a "host limit" can be a big problem,
as it may cause hosts to "lose and regain" units seemingly at random.
If an EtherLite has one available connection, and two hosts wish to use it, the
connection is simply given to who gets there first, NOT to who might have
had it previously. This can be very confusing, so one should take care to
administrate this correctly!
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