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146 C
HAPTER
8: E
THERNET
Ethernet Overview
Ethernet is a standardized, switched, packet-based network that supports
an exponential hierarchy of three line speeds:
■
10 Mbps — Ethernet
■
100 Mbps — Fast Ethernet
■
1000 Mbps — Gigabit Ethernet
All speeds of Ethernet are based on an IEEE 802.3 standard protocol
called Carrier Sense Multiple Access with Collision Detection (CSMA/CD),
which controls network access. With CSMA/CD, a station that intends to
transmit listens for other Ethernet traffic on the network. When the
station does not detect network activity, the station transmits.
Features You can configure these features on Ethernet ports:
■
Port state
— Whether a port is
enabled
(placed online) or
disabled
(placed off-line)
■
Port label — An alphanumeric port identifier
■
Port mode — Port speed (10 Mbps, 100 Mbps, or 1000 Mbps) and
duplex mode (half-duplex or full-duplex)
■
Autonegotiation — A feature that allows some ports to
automatically identify and negotiate speed and duplex mode with a
receiving device
■
Flow control — A Fast Ethernet or Gigabit Ethernet port mode that
pauses and resumes transmissions
■
PACE
®
Interactive Access — An algorithm that reduces network
jitter, provides reliable timing, and optimizes LAN bandwidth use
In addition, some important Ethernet features depend on which Ethernet
equipment you use, how you configure it, and how you connect it:
■
Trunking — Increases bandwidth between switches and servers
■
Trunk Control Message Protocol (TCMP) — Increases the
availability of trunked links by handling physical configuration errors
■
Gigabit Interface Converter (GBIC) — A Gigabit Ethernet port
media type that allows you to hot-swap one media connector without
affecting the other connectors