User guide

A-12 Cisco 2500 Series Access Server User Guide
LANs and WANs
Ethernet LANs
The IEEE has established Ethernet as standard 802.3. Ethernet uses a 10-Mbps bus.
Ethernet LANs use carrier sense multiple access collision detect (CSMA/CD) for bus
access control. Several physical layer implementations have been established for Ethernet;
the more common implementations are as follows:
• 10Base5—Ethernet on thick coaxial cable. This implementation was based on the
original Ethernet and is not in common use today. Maximum segment length is 1,640
feet (500 m).
• 10Base2—Ethernet on thin coaxial cable. 10Base2 cabling is similar in appearance to
TV cable, but uses a different specification. Maximum segment length is 656 feet
(200 m).
• 10BaseT—Ethernet on unshielded twisted-pair (UTP) wiring. 10BaseT is similar to the
wiring used for phones, but must meet certain electrical standards in order to be used.
Maximum segment length is 328 feet (100 m).
Configuring Ethernet
Special configuration commands are not required for the Ethernet interface on the
Cisco 2500 series access server. The Ethernet configuration commands are as follows:
• show interface—an EXEC command that displays information about the interfaces
attached to the access server.
• [no] shutdown—a config-interface subcommand, that enables or disables operation of
the configured interface.
Token Ring LANs
The IEEE has established Token Ring as standard 802.5. Different physical
implementations of Token Ring are available, including variations on shielded twisted-pair
(STP) and UTP cabling. Token Ring is very common in IBM environments.
Token Ring can operate at two different ring speeds: 4 Mbps and 16 Mbps. All devices on
the ring must agree on the operating speed.