|
Gigabit Ethernet technology is fully backward compatible with
the existing Ethernet protocol, but increases speed tenfold over
Fast Ethernet to 1000 Mbps, or 1 gigabit per second (Gbps). The
Gigabit Ethernet protocol has been ratified by IEEE under the 802.3-2000
standard, which encompasses the previous 802.3z and 802.3ab standards.
The original Ethernet specification was defined by the frame format
and support for CSMA/CD (Carrier Sense Multiple Access with Collision
Detection) protocol, full duplex, flow control, and management objects
as defined by the IEEE 802.3 standard. Gigabit Ethernet looks identical
to Ethernet from the data link layer upward and implements all these
functions. At the physical layer, in addition to UTP cables, Gigabit
Ethernet supports fiber optic media, enabling it to deliver the
1 Gbps data rate as a campus backbone.
An Ethernet Media Access Control (MAC), (Layer 2 of the OSI model)
connects to the PHY (Layer 1) physical media (optical or copper).
Ethernet architecture further divides the PHY into a Physical Media
Dependent (PMD) and a Physical Coding Sublayer (PCS). Optical transceivers,
for example, are PMDs. The 1000BASE-X PCS consists of coding (e.g.,
8b/10b) and Auto-Negotiation functions.
Advantages of Gigabit Ethernet
- Uses the same frame format and transmission schemes as fast
Ethernet.
- Uses the same management schemes as existing Ethernet.
- Minimal training investment is required. Design, installation
and configuration remain the same.
- Not as support intensive. Familiarity with the protocol and
methodologies means less impact on MIS resources.
|
