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Line Speeds and Performance 185

Line Speeds and Performance

Although the Eicon SNA Gateway software lets you adjust network parameters

for the best performance, certain restrictions inherent to the network itself can

limit throughput. Line speeds in excess of 128 kbps are possible on dedicated

lines, but public X.25 data networks may be as slow as 2400 bps. A slow line

will be filled before the Eiconcard reaches its transmission capacity.

Note

To modify the parameters discussed in this section, run the Eicon

Configuration Program. If you are unfamiliar with communications protocols,

you should not experiment with parameter settings.

Propagation Delay

Propagation delay is a pitfall of public networks. Propagation delay is the time

taken for signal transmission, error checking, and queuing between all the

nodes in the transmission path. On some links, such as the ones serviced by

satellites, round trip transmission time can approach a full second. Large

propagation delays are often observed during heavy traffic periods.

Two features of the X.25 protocol work to minimize the impact of propagation

delay.

• X.25 does error checking between intermediary nodes. This allows packets

to be transmitted without waiting for end-to-end acknowledgment.

• X.25’s windowing capability increases the number of packets that can be

sent before receiving confirmation from the next node in the transmission

path.

Novell NetWare Networks

Different versions of Novell NetWare IPX on the gateway and the

workstation(s) can reduce performance or cause problems Make sure you use

the latest version of IPX on the gateway and workstations(s).

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Eicon Networks C21 Guida di Installazione Pagina 185