3Com NETBuilder SI, Инструкция по использованию

Страница: 170 / 212

170 A
PPENDIX
D: C
ONNECTORS AND
C
ABLES
WAN Connector
and Cables
The WAN connector can be an ISDN S/T (model 43x and 53x), ISDN U
(model 44x and 54x), 56/64 Kbps CSU/DSU (model 45x and 55x), or
T1/FT1 CSU/DSU (model 46x and 56x) connector, depending on the
interface module installed.
ISDN S/T Cable To connect a model 43x or model 53x bridge/router to an ISDN network,
use a Category 5 shielded twisted-pair cable with an RJ-45 connector on
both ends. 3Com does not supply this cable.
Table 23 Maximum Cable Length in Example Collision Domain Diameters
Maximum Combined Cable Length, by Interface
Scenario TX and/or T4 FX Only FX & TX FX & T4
No Repeaters
(see Figure 22) 100 m 412 m not applicable not applicable
One Class 1 repeater *
(see Figure 23)
200 m — 100 m max. on
each side of the repeater
272 m 260.8 m
100 m max. TX
Remaining length of FX
231 m
100 m max. T4
Remaining length of FX
One Class 2 repeater †
(see Figure 23)
200 m — 100 m max . on
each side of the repeater
320 m 308.8 m
100 m max. TX
Remaining length of FX
304 m ‡
100 m max. T4
Remaining length of FX
Two Class 2 repeaters
(see Figure 24) 205 m — 100 m max . per
cable span
228 m 216.2 m
105 m max. total TX, 100
m max. per TX cable span
Remaining length of FX
263.3 m
‡
105 m max. total T4, 100
m max. per T4 cable span
Remaining length of FX
* A high-delay repeater as specified in IEEE 802.3 standards. A Class 1 repeater usually connects dissimilar media, for instance, UTP to
fiber.
† A low-delay repeater as specified in IEEE 802.3 standards. A Class 2 repeater usually connects similar media, for instance, UTP to UTP.
‡ This scenario is unlikely, because Class 2 repeaters do not usually connect FX to T4.