Black Box LH8050A, Installation And User Manual

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Black Box Mixed-Media Fiber Hubs Installation and User Guide (4/99)
Twisted pair user cable length, TL < (4 BT) / (1.112 m/BT)
TL < 3.6 meters for two hub-to-hub cascading cables
⇒
2
meters (6 ft.) length max. for each of the cascade segments,
In the above example, 75 is the BT delay for 70m of Category 5 cable (1.112 BT/m), 80 is the
bit time delay for each LH8050A front-to-front ports, 100 is the BT delay for the TX DTE pair
in the user stations, and 2 BT is the safety margin applied.
26
Figure 3.6.1b: Multiple
cascaded LH8050A Mixed-
Media Fiber Hubs
Note that the cascading
of multiple LH8050A Mixed-
Media hubs is a capability beyond
what industry standards normally
permit, and is different from what competitive 100Mbps Class II hub products normally allow.
This additional cascading level and cable length is due to the relatively shorter bit time (80 BT
actually measured, for front-port-to-port) delay of the LH8050A vs. the industry standard
delay of 92 BT for Class II repeaters. The installation flexibility and network growth potential
is accordingly better with LH8050As than with hubs that merely meet the standard.
Table 3.6.1c shows maximum cable lengths for common network configurations
using industry standard repeater PDV numbers. Calculations such as above should be
performed using measured PDV data supplied by the equipment manufacturer in important
installations.
Table 3.6.1c: Maximum segment lengths for common network configurations
Number
of Hubs
Repeater
Hop Count
Max. User
Segment
Lengths (m)
Max. Inter-
Repeater (Cascade)
Length (m)
Notes
1 1 100.0 n.a. All ports TX
2 2 100.0 5.0 All ports TX
2 2 92.0 20.0 All ports TX
3+ 3 60.0 1.0 All ports TX
Instructions for connecting the LH8050A Mixed-Media Hubs to the various Fast
Ethernet media are given in the following sections.
3.6.2 Connections to NICs which support Auto-Negotiation
2 meter Cat. 5 cable
for cascading
All user devices connected
via Cat. 5 twisted pair cable
of up to 75m length.
10 10 0
PWR BRD
ACT
COL
Magnum 8000 X
Mixed Media Hub
GAR TT RE
1
R L S R L S R L S R L S R L R L R L R L R L R L R L R L R L R L R L R L
10 10 0
PWR BRD
ACT
COL
Magnum 8000 X
Mixed Media Hub
GA T RRET
1
R L S R L S R L S R L S R L R L
R L
R L R L R L R L R L R L
R L R L R L
10 10 0
PWR BRD
ACT
COL
Magnum 8000 X
Mixed Media Hub
GAR TT RE
1
R L S R L S R L S R L S R L R L
R L
R L R L R L R L R L R L
R L R L R L