HP 600 Series, Services And Applications

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Inverse multiplexers are available from several companies including Ascend,
Simplex, and Presticom. Additional features can include data compression,
Switched 56 and PSTN switched-circuit types, and leased-line support with
incremental switched-circuit bandwidth.
Application Recovery
One question that often arises when considering router networks with
backup mechanisms is: “Will my application recover transparently after a
primary circuit fails?”. There are two requirements that must be met for
network applications to recover when failures in router-based networks
occur:
First, the router network must have another route to the target sys-
tem or network, and the routers must be able to detect failures and
establish alternate routes quickly. The routing protocols, as well as
the Spanning Tree Protocol, meet the fast switching criteria.
Second, the network architecture on which the application runs
must have recovery mechanisms (usually in the transport layer) to
tolerate brief communication failures.
Applications running at the time of the failure may or may not recover
transparently. IP applications will almost always recover transparently.
NetWare users may receive an “Abort, Retry, Fail” message. (Answering
“Retry” will generally succeed in restoring communications.) DECnet
applications may fail when default network parameters are used. However,
you may modify DECnet transmission parameters to increase the applica-
tions’ tolerance of temporary network failures.
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Improving Network Availability
Application Recovery
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