These two terms actually refer to different things:
Ethernet
is a communication technology and
IEEE802.3
is a variety of Ethernet. Ethernet, in the more specific sense, is a
carrier sense, multiple
access/collision detection (CSMA/CD)
local area network. An Ethernet network uses these
attributes—carrier sense, multiple access, and collision detection—to enhance communication. This
definitely does
not
mean that Ethernet is the only technology that uses these attributes. In today’s
technical jargon, however, the term
Ethernet
is getting closer to meaning
all
CSMA/CD technologies.
Both Ethernet and IEEE 802.3 are broadcast networks. All frames that cross a given segment
can be heard by all machines populating that segment. Because all machines on the segment have
equal access to the physical media, each station tries to wait for a quiet spot before it transmits its
data. If two machines talk at the same time, a collision occurs.
Ethernet services both the Physical and Data Link layers, whereas IEEE 802.3 is more concerned
with the Physical layer and how it talks to the Data Link layer. Several IEEE 802.3 protocols
exist; each one has a distinct name that describes how it is different from other IEEE 802.3
protocols. Table 36.3 summarizes these differences.
TABLE 3 6 . 3
IEEE 802.3 Characteristics
802.3
Values
Data Rate
(Mbps)
Signaling
Method
Maximum
Segment
Length (m) Media Topology
10Base5 10 Baseband 500 50 Ohm coax Bus
10Base2 10 Baseband 185 50 Ohm coax Bus
1Base5 1 Baseband 185 Unshielded twisted pair Star
10BaseT 10 Baseband 100 Unshielded twisted pair Star
100BaseT 100 Baseband 100 Unshielded twisted pair Star
10Broad36 10 Broadband 1800 75 Ohm coax Bus
1000BaseT 1000 Baseband 100 Unshielded twisted pair Star
Table 36.3 is an excerpt from Cisco documentation; for the full document,
please see
www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/
ethernet.htm
.
In Table 36.3, you will notice that the terms baseband and broadband are used to describe
the signaling type. In a baseband transmission, only a single frequency is used for sending data,
and therefore only a single signal can be sent over the same media. A broadband signal multiplexes
multiple signals of different frequencies together on the same physical media.
Though not specifically called out in the table, there are four different IP encapsulation types
supported by Cisco for Ethernet: ARPA, SNAP, Novell-Ether, and SAP. Of these, ARPA is the
default encapsulation type used.