Cabletron-systems 2000 User Manual download pdf (Page 54)

The SmartSwitch 2000 Chassis View

2-32 Managing the Hub

Use the options in this window to select the desired mode:

Standard Mode

In Standard Mode, an interface can only either transmit or receive at any given

time, and must wait for one activity to be completed before switching to the next

activity (receive or transmit). In this mode, standard wire speeds (10 Mbps for

Ethernet, 100 Mbps for FDDI) are available.

Full Duplex

In Full Duplex Mode, an interface can both receive and transmit packets at the

same time, effectively doubling the available wire speed to 20 Mbps (for Ethernet)

or 200 Mbps (for FDDI).

Be sure to click on the Apply button to set your changes; note that the interfaceÕs

current mode can be determined by the Þeld selected in the window.

TIP

Note that, if you select the ConÞguration option available for a Fast Ethernet interface,

an entirely different window will appear; see ConÞguring Fast Ethernet Ports on First

Generation Devices, on page 2-33, or ConÞguring Ethernet Ports on Second

Generation Devices, on page 2-38, for information on conÞguring these ports.

WARNING

For standard Ethernet interfaces, Full Duplex should only be enabled on an interface that

has a connection to a single destination address at the other end of the connection (i.e., it is

not a segment with an attached repeater cascading the connection to multiple destination

addresses).

Full Duplex mode disables the collision detection circuitry at the interface, so that both

Transmit and Receive wires can be used simultaneously. With a single destination address

at the other end of the connection (for example, if the connection was to a full duplex

interface on another switching device, or if a single Þle server was connected to the full

duplex switch port), this essentially doubles the available bandwidth from 10 Mbit/sec to

20 Mbit/sec. Note that the interface at the other end of the connection must also have Full

Duplex enabled at the attached interface.

Full Duplex mode must be disabled if the interface is communicating with multiple

destinations simultaneously (i.e., if a repeater is cascaded from the interface), since

Ethernet relies on Collision Sense for proper operation.

Similarly, an FDDI Full Duplex connection must also only be run point-to-point between

two supporting FDDI interfaces (e.g., another HSIM-F6), since the dual bandwidth is

attained by running data on both primary and secondary paths simultaneously. Since

Full Duplex overrides standard FDDI protocol (and eliminates ring redundancy), it will

not operate in a ÒringÓ conÞguration, but only as a point-to-point high speed data trunk

between hubs. Note that you must use Local Management to conÞgure your HSIM-F6 for

Full Duplex operation prior to making physical connections. Refer to your Local

Management Guide for more information.

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Cabletron-systems 2000 User Manual Page 54