Clarion M10 Series Bedienungsanleitung PDF herunterladen (Seite 7)

C-SPEC CORPORATION WIRELESS PRODUCTS

CLARION MerLAN M10 5

multiple ethernet devices. Duplicate frames that the MerLAN M10 does not

filter out will be removed by a function of the Network Operating System.

The maximum number of re-transmissions is seven (eight transmissions

total) after which the data is dropped and the successful transmission will

depend upon another re-transmission provided by the Network Operating

System protocol. The value of the ACK frame time-out is currently fixed at

300 micro seconds. It will be updated to a user definable time through the

configuration process in the future to support various ranges of wireless link

distances.

FLOW CONTROL

When no buffers are available for an Upload of AUI frames to the MerLAN

M10, the unit will take one of two separate courses depending upon the

option selected during the configuration process. The first course of action,

which is also the default, is for the unit to invoke flow control by using the

collision signal to force the ethernet card into its exponential back-off

algorithm. Because there are eight upload buffers, this flow control can

always maximize the RF throughput even though the attached device may

delay re-offering frames. The second course of action, which is an option that

can be chosen during the configuration process, is to ignore upload frames

when no upload buffer is available. This may be required when the MerLAN

M10 is connected to multiple computers (e.g., via a hub) which might be

disrupted by excessive collision indications. However, ignored frames will

incur a large delay for retransmission by the level-4 transport protocol (TCP,

SPX), or may not be re-offered at all for datagrams (UDP, IPX). Although

using the collision signal for flow control is the default, the user must make

an informed selection between the two possibilities based upon network

topology, acceptable link behavior, and the requirements of the application

software.

SECURITY

Since secure data is a great concern with any wireless transmission system,

the MerLAN M10 offers excellent security without using conventional

cryptography. The security of the data transmissions is achieved by

continuously changing and pseudo-randomly selecting spreading codes. The

user may select from 2

(64K) different sequences to determine the order in

which the spreading codes are used. This provides excellent security against

eavesdropping by unintended parties. The actual sequences can be selected

through the configuration process provided by the MerLAN M10

configuration software.

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Clarion M10 Series Bedienungsanleitung Seite 7