Magnum 6K32 & 6K32T Managed Switch Installation and User Guide (12/05)
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4.5
Flow-control, IEEE 802.3x standard
Magnum 6K32T Switches incorporate a flow-control mechanism for Full-
Duplex mode. The purpose of flow-control is to reduce the risk of data loss if a long
burst of activity causes the switch to save frames until its buffer memory is full. This is
most likely to occur when data is moving from a 100Mb port to a 10 Mb port and the
10Mb port is unable to keep up. It can also occur when multiple 100Mb ports are
attempting to transmit to one 100Mb port, and in other protracted heavy traffic situations.
Magnum 6K32T Switches implement the 802.3x flow control (non-blocking)
on Full-Duplex ports, which provides for a “PAUSE” packet to be transmitted to the
sender when the packet buffer is nearly filled and there is danger of lost packets. The
transmitting device is commanded to stop transmitting into the 6K32T Switch port for
sufficient time to let the Switch reduce the buffer space used. When the available free-
buffer queue increases, the Switch will send a “RESUME" packet to tell the transmitter
to start sending the packets. Of course, the transmitting device must also support the
802.3x flow control standard in order to communicate properly during normal operation.
Note: When in Half-Duplex mode, the 6K32T Switch implements a back-pressure
algorithm on 10/100 Mb ports for flow control. That is, the switch prevents frames from
entering the device by forcing a collision indication on the half-duplex ports that are
receiving. This temporary “collision” delay allows the available buffer space to improve
as the switch catches up with the traffic flow.
5.0
Magnum 6K32T Managed Switch Port Modules
This chapter describes each Port Module (PM), including appearance,
functionality, and status displays.
5.1
Inspecting the Package and Product
This section applies only to PMs shipped as separate items, i.e., 6K32T PMs
not factory installed in a Magnum 6K32T modular slot.
Examine the shipping container for obvious damage prior to
installing a 6K32T PM; notify the carrier of any damage you believe occurred
during shipment or delivery. Inspect the contents of this package for any signs
of damage and ensure that the items listed below are included.
This package should contain:
6K32T PMs
Installation instructions, with illustrations
Remove the 6K32T PM(s) from the shipping container. Be sure to
keep the shipping container should you need to ship any of the PMs separately
