100Base-Fx And 1000Base-Sx Ports - Cisco Catalyst 2950 Hardware Installation Manual

Chapter 2 Overview
Note
Note

100BASE-FX and 1000BASE-SX Ports

78-11157-05
When connecting the switch to workstations, servers, and routers, be sure to use
a twisted-pair straight-through cable. When connecting the switch to hubs or other
switches, use a twisted-pair crossover cable. Pinouts for the cables are described
in Appendix B, "Connectors and Cables."
The 10/100/1000 ports on the Catalyst 2950T-24 switch can be explicitly set to
operate at 10, 100, or 1000 Mbps but only in full-duplex mode. The 10/100/1000
ports on the Catalyst 2950 LRE switches can be explicitly set to operate at 10
or 100 Mbps in full- or half-duplex mode or at 1000 Mbps in full-duplex mode.
The 10/100/1000 ports can also be set for speed autonegotiation, compliant with
IEEE 802.3AB. In all cases, the cable length from a switch to an attached device
cannot exceed 328 feet (100 meters).
On the Catalyst 2950 LRE switches, the four input uplink ports are bundled as two
logical ports, each consisting of a copper 10/100/1000 port and a fiber-optic SFP
module slot, respectively.
Within each logical port, you can use only the copper or the fiber-optic port at one
time. If a Catalyst 2950 LRE switch senses more than two connections for both
logical ports, the switch chooses the fiber-optic connections over the copper
connections in default operation.
See the "SFP Module Slots" section on page 2-14
uplink logical ports.
The 100BASE-FX and 1000BASE-SX ports both use 50/125- or 62.5/125-micron
multimode fiber-optic cabling. The 100BASE-FX ports operate only at 100 Mbps
in full-duplex mode, and the 1000BASE-SX ports operate only at 1000 Mbps in
full-duplex mode.
In full-duplex mode, the cable length from a 100BASE-FX port on a switch to an
attached device cannot exceed 6562 feet (2 kilometers). The cable length from
a 1000BASE-SX port on a switch to an attached device cannot exceed 1804 feet
(550 meters).
Catalyst 2950 Desktop Switch Hardware Installation Guide
Front-Panel Description
for more information on LRE
2-11