3Com 3C17203 - SuperStack 3 Switch 4400, Implementation Manual

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Switch Features Explained 19
capabilities — these capabilities are by default the parameters that
provide the highest performance supported by the port.
1000BASE-SX ports do not support auto-negotiation of port speed.
Ports operating at 1000 Mbps only support full duplex mode.
For details of the auto-negotiation features supported by your Switch,
please refer to the Management Quick Reference Guide that
accompanies your Switch.
Duplex
Full duplex mode allows packets to be transmitted and received
simultaneously and, in effect, doubles the potential throughput of a link.
Flow Control
All Switch ports support flow control, which is a mechanism that
minimizes packet loss during periods of congestion on the network.
Flow control is supported on ports operating in half duplex mode, and is
implemented using the IEEE Std 802.3-2002 (incorporating 802.3x) on
ports operating in full duplex mode.
Smart Auto-sensing
Smart auto-sensing allows auto-negotiating multi-speed ports, such as
10/100 Mbps or 100/1000 Mbps, to monitor and detect high error rates,
or problems in the “physical” interconnection to another port. The port
reacts accordingly by tuning the link from its higher speed to the lower
supported speed to provide an error-free connection to the network.
1000BASE-SX ports do not support smart auto-sensing.
For more information about auto-negotiation and port capabilities, see
Chapter 2 “Optimizing Bandwidth” .
Multicast Filtering Multicast filtering allows the Switch to forward multicast traffic to only
the endstations that are part of a predefined multicast group, rather than
broadcasting the traffic to the whole network.
The multicast filtering system supported by your Switch uses IGMP
(Internet Group Management Protocol) snooping to detect the