3Com 5500-EI Getting Started Manual page 17

Switch 5500 Family — Front View 17
You can disable auto-negotiation. You can manually configure these
ports to 10 Mbps half duplex, 100 Mbps half duplex,
10 Mbps full duplex, or 100 Mbps full duplex. It is not possible to
manually configure a 1000 Mbps link because auto-negotiation is
mandatory in the 1000 Mbps standard. If you disable auto-negotiation,
Auto MDIX cannot function and the ports become fixed in MDIX
(cross-over) mode.
If you disable auto-negotiation on a 1000 Mbps port, the speed drops to
the highest available speed, which is 100 Mbps by default.
1000BASE-X SFP Ports The 1000BASE-X SFP (Small Form Factor Pluggable) ports support fiber
Gigabit Ethernet short-wave (SX), long-wave (LX), long-haul (LH70), and
copper (T) SFP Transceivers in any combination. This offers you the
flexibility of using SFP transceivers to provide connectivity between the
Switch and remote 1000 Mbps workgroups, or to create a high capacity
aggregated link backbone connection.
The default state for these ports is auto-negotiation enabled, where the
speed, duplex and flow control modes are negotiated. As the speed and
duplex modes are fixed by the media type, only the flow control is
negotiated with the link partner. Alternatively, auto-negotiation can be
disabled (except 1000BASE-T where auto-negotiation is mandatory) and
the flow control setting can be manually configured.
You can also use these ports for stacking the 5500 SI and EI. For
information about stacking these switches, see the section entitled
"Guidelines For Interconnecting Units" on page 78.
100BASE-X SFP Ports The Switch 5500-EI FX has 24 100BASE-X SFP ports. These are 100Mbps
(Switch 5500-EI FX ports that can use multi-mode fiber optic cables of up to 2km and
only) single-mode fiber optic cables of up to 10km.
You must manually configure duplex and flow control.
The Switch 5500-EI FX supports copper transceivers on the Gigabit SFP
ports only.
Console Port The console port allows you to connect a terminal and perform remote or
local out-of-band management. As the console port on the Switch is an
RJ-45 port, you must connect an RJ-450 to DB9 converter cable to a
standard null modem cable in order to connect a terminal.