Cabletron Systems STS16-20D, STS16-20R - page 122

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SmartStack STS16-20D/STS16-20R Token Ring Switches Installation and User Guide Switch Configuration
Force AC Bits on SR Frames
This field specifies if AC bits will be set unconditionally when a port forwards
certain LLC frames. Possible values are Yes and No (default).
BRF MTU (actual)
Display only. The MTU the BRF uses at the moment.
Port MTU
Configures the Maximum Transmission Unit size of the information field of
packets to be sent or received. Possible values are 1,500 and 4,472, 8,144, 17,800
and USE Brf (default).
The actual value used is the lower of the configured value and the actual BRF MTU.
➽Note! See the description on frame length limit on page41 in Chapter 3, “Preparing
for Installation”.
Forwarding Mode
The forwarding mode that will be used by this port, when forwarding frames to
other ports in this box. Cut-through is possible only if all exit ports are running 16
Mbps. Possible values are auto, cut-through, and store & forward. The default is
auto. If the forwarding mode is set to auto, the actual mode will depend on the
number of errors that occur on this port during the sampling interval. If the error
rate is below the error low threshold, cut-through mode is used. If the error rate is
above the Error High Threshold value, store & forward is used. The store &
forward mode is always used for ports with a media speed of 4 Mbps.
Error High Threshold
This field is only valid when Forwarding Mode is set to auto. It is used to force a
port to store & forward mode when the percentage of errors detected in the Error
Sampling Interval is greater than the Error High Threshold. Possible values are
0–100 percent. The default value is 10 percent.
Error Low Threshold
This field is only valid when Forwarding Mode is set to auto. It is used to return
a port to cut-through mode when the percentage of errors detected in the Error
Sampling Interval is less than the Error Low Threshold. Possible values are
0–100 percent. The default value is 1 percent.
Error Sampling Interval
This field is only valid when Forwarding Mode is set to auto. It specifies a
sampling period in minutes. The sampling period is used when counting errors to
determine a port’s forwarding mode. Possible values are 1–60 minutes. The default
value is 10.