3Com EtherLink III ISA 3C509B-COMBO, Руководство пользователя

Страница: 87 / 110

Advanced Options Tab B-3
The following advanced values can be modified to regulate PACE
traffic on the network.
FIFO Packet Threshold
Controls the number of non-PACE packets that the network driver
allows in the FIFO ahead of PACE packets. A smaller number
decreases the time between PACE packets, but it can also
decrease performance. The recommended setting is 3.
Concurrent UDP Streams
Controls the number of simultaneous multimedia UDP packet
streams that the network driver can handle at any given time. For
many applications, the number of UDP streams is the same as the
number of connections.
For example, a videoconference with three people at three
different sites uses three concurrent UDP streams for the video
data. The concurrent UDP streams setting must be a power of two
(2, 4, 8, 16, etc.), but the optimal value varies depending on your
PC and the application that you are running.
Although a video server can support up to 32 connections, a client
may only want to conference with four other people at a time.
The recommended setting is 16.
Low-Priority Ratio
When PACE support is enabled, high-priority packets are always
transmitted before low-priority packets. If a high-priority application
sends out a sufficiently high number of high-priority packets,
low-priority packets may not be sent.
To prevent this problem, the driver uses a ratio setting to periodically
send out a low-priority packet (if one is waiting to be sent). For
example, if a value of 1000 is entered, one low-priority packet
would be sent for every 1,000 high-priority packets. The
recommended setting is 25.
Natural Packet Interval
To communicate packet priority to interconnect devices (repeaters,
switches, and the like), the PACE driver slightly modifies the
Ethernet packet. Because of this, connection problems may
result when these modified packets are sent out for long periods
of time during which no low-priority packets are sent. To get
around this problem, the driver can be configured to periodically
send out an unaltered, natural packet. The recommended setting
is 180 seconds.