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<== Date ==> <== Thread ==>

Subject: RE: CA gateway question
From: "Jeff Hill" <[email protected]>
To: "'Martin L. Smith'" <[email protected]>, "'Artem Kazakov'" <[email protected]>
Cc: "'Ken Evans'" <[email protected]>, "'Ralph Lange'" <[email protected]>, "'EPICS-tech-talk'" <[email protected]>
Date: Wed, 29 Nov 2006 15:19:58 -0700
> Also, I'm not sure what would happen to the client if the
> particular gateway serving a PV stops .... would the client be able
> to automatically get the PV from the other gateway ?? I'm not sure.

The client library would eventually find the PV in the other gateway, and
connect through the other gateway. How fast it would switch over depends on
how it lost contact with the original gateway. If the network path to the
original gateway was severed it might take a relatively longer amount of
time to switch over - approximately as long as the TCP keep-alive interval
parameter specifies. If the gateway process is stopped, but its host is
still alive and responding on the network, then the client library would
take a relatively shorter amount of time to discover the problem and switch
over to the other gateway - approximately EPICS_CA_CONN_TMO seconds. The
software is specially designed to operate this way with recent versions of
R3.14 so that there isn't a tendency in EPICS systems for congestion
feedback.

Jeff



Replies:
Re: CA gateway question Artem Kazakov
References:
Re: CA gateway question Martin L. Smith

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