3com 7600 Benutzerhandbuch
11-4
C
HAPTER
11: E
THERNET
LAN
S
AND
B
RIDGES
IN
THE
7600 C
ARD
10 or 100 Mbps Speed
The 7600 Card can communicate with either a 10 Mbps or in a 100
Mbps communication rate. This capability is available for the Tx port
type only. The Fx ports communicate in 100 Mbps only. The Tx ports
also have a speed auto-negotiation capability. When speed
auto-negotiation is selected, the speed in which the 7600 Card chooses to
operate is determined by the communication speed available in the
device with which it is communicating. If the device with which it
communicating also has a 100 Mbps speed (such as another 7600 Card)
then it communicates in 100 Mbps, otherwise it communicates in 10
Mbps. The Fast Ethernet uses a lower bit-time (the time duration of each
bit transmitted), but leaves the remainder of the Ethernet CSMA/CD
unchanged.
Mbps communication rate. This capability is available for the Tx port
type only. The Fx ports communicate in 100 Mbps only. The Tx ports
also have a speed auto-negotiation capability. When speed
auto-negotiation is selected, the speed in which the 7600 Card chooses to
operate is determined by the communication speed available in the
device with which it is communicating. If the device with which it
communicating also has a 100 Mbps speed (such as another 7600 Card)
then it communicates in 100 Mbps, otherwise it communicates in 10
Mbps. The Fast Ethernet uses a lower bit-time (the time duration of each
bit transmitted), but leaves the remainder of the Ethernet CSMA/CD
unchanged.
Cabling
Fast Ethernet supports structured wiring composed of category 3, 4, and
5 unshielded twisted pair (UTP), 150 ohm shielded twisted pair (STP) and
fiber. These media specifications cover almost all cable types currently in
use. Equally important, all supported media types can be mixed together
and connected through a repeater or switch, just as with the earlier
Ethernet media types.
5 unshielded twisted pair (UTP), 150 ohm shielded twisted pair (STP) and
fiber. These media specifications cover almost all cable types currently in
use. Equally important, all supported media types can be mixed together
and connected through a repeater or switch, just as with the earlier
Ethernet media types.
To support these various wiring types, Fast Ethernet provides three
transceiver types. A transceiver is that portion of an adapter containing
the analog circuitry necessary to transmit and receive data on a physical
cable. In Table 11-2, each transceiver type supports a different set of
cable applications. It lists two twisted-pair-type transceivers and one fiber
transceiver. These three Fast Ethernet transceiver technologies are
complementary. The 7600 Card module uses the STP and fiber cable
types.
transceiver types. A transceiver is that portion of an adapter containing
the analog circuitry necessary to transmit and receive data on a physical
cable. In Table 11-2, each transceiver type supports a different set of
cable applications. It lists two twisted-pair-type transceivers and one fiber
transceiver. These three Fast Ethernet transceiver technologies are
complementary. The 7600 Card module uses the STP and fiber cable
types.
Table 11-2 Cable Support by Transceiver Type
Transceiver type
Cable type
Number of
pairs (fibers)
pairs (fibers)
Notes
100BASE-T4
Category 3 UTP
Category 4 UTP
Category 5 UTP
Category 4 UTP
Category 5 UTP
4
4
5
4
5
Workhorse design
for category 3 cable,
100-m link span
for category 3 cable,
100-m link span
100BASE-TX
Category 5 UTP
150
150
Ω
STP
2
2
2
Only needs two
pairs, 100-m link
span
pairs, 100-m link
span
abtthgde.book Page 4 Tuesday, June 23, 1998 10:29 AM