3Com TR - Manual (Page 66)

4-8 C HAPTER 4: C ONFIGURING WITH THE VT100 I NTERFACE
ring ahead in the queue. The frame that has been
buffered for the busy or down queue is discarded
so that deliverable packets can proceed.
■ Disabled—In the disabled mode, neither Flow
Control or Non-blocking are in use.
1 Set this field to one of the aforementioned fields by
toggling the [Space Bar].
2 Press [Return].
Setting Port Speed
Speed sets the data rate of ports. Choices:
■
16 Mbps (default)
■
4 Mbps
1 Set this field by toggling the [Space Bar].
2 Press [Return].
Setting Forwarding Mode
Set the forwarding mode for individual ports using
this field. Choices:
■ Store & Forward—In this mode, packets are
received and buffered (stored) in their entirety until
they are forwarded. Errored frames will not be for-
warded on the source ring. Although this guaran-
tees packet stability, it also involves a transit delay.
■ Cut-thru—Cut-thru avoids the transit delay found
in standard store-and-forward methods. Cut-thru
can only be applied between ports that are operat-
ing at the same wire speed or from a high-speed
port to a low-speed port.
■
Dynamic Cut-thru—Dynamic Cut-thru monitors
the error rates on the port. If a user-defined thresh-
old is exceeded, the switch port changes to
store-and-forward until the error rate reduces.
Once the error rate is reduced, the switch returns
to cut-thru mode.
1 Set this field by toggling the [Space Bar].
2 Press [Return].
Dynamic Cut-Thru Threshold%
The Dynamic Cut-Thru Threshold% field allows you
to view the forwarding mode threshold percentage,
which determines the degree to which errored pack-
ets are allowed to pass before the Switch 2000 TR
reverts to Store & Forward mode. These thresholds
apply only when the Switch 2000 TR is configured in
Dynamic Cut-thru mode. The two threshold fields are:
■ Rising Threshold—When this threshold is
exceeded, the Switch 2000 TR reverts to
Store&Forward mode.
■ Falling Threshold—When this threshold is
crossed, the Switch 2000 TR reverts to Cut-thru
mode.
Setting the Locally Admin. Address
The Locally Administered Address field allows you to
assign individual MAC addresses to each port. This
feature is useful for identifying specific ports by their
addresses.