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Table 1 lists the Token Ring industry guideline for the maximum lobe length of shielded twisted-pair
(STP) and unshielded twisted-pair (UTP) cable.
Table 1 Industry Lobe Length Guideline
Lobe lengths for Digital’s MAUs exceed the industry guideline. Specifically, lobe lengths can be longer
than the industry guideline for STP cable and UTP level 5 cable at 4 Mb/s. See Table 2, Digital Lobe
Length Guideline, for the maximum lobe lengths for Digital’s MAUs. Also refer to either “DEChub 900
MultiSwitch Configuration or DEChub ONE Configurations” below for more configuration information.
Table 2 Digital Lobe Length Guideline
1
1
All distances include patch cables and hub connections.
Digital recommends that you keep lobe lengths within the maximums found in the industry guideline
whenever possible. This allows for future network expansion and upgrade. When current needs
dictate the longer lobe lengths, you can increase lobe lengths up to the maximums in Digital’s guideline
without any negative effect on the network.
DEChub 900 MultiSwitch Configuration
Multiple Hubs
A repeater is needed in each hub to connect hubs in a multiple hub network. Refer to the
appropriate Token Ring repeater manual for specific information.
DEChub ONE Configurations
Unshielded Twisted-Pair Cable Configurations:
Multiple MAUs in One Wiring Closet at 16 Mb/s
At 16 Mb/s, a maximum of five MAUs can be in one wiring closet without affecting maximum lobe
length. Subtract 10 meters from the lobe lengths in Table 2 for each additional MAU above five in a
wiring closet.
Multiple Wiring Closets
Digital recommends that you use repeaters to segment the ring in a network with multiple wiring
closets. In some situations, only one, or no repeaters, are required. Refer to the appropriate
Token Ring repeater manual for specific information.
UTP STP
Speed Level 3 Level 5
4 Mb/s 100 m (327 ft) 100 m (327 ft) 100 m (327 ft)
16 Mb/s 65 m (213 ft) 100 m (327 ft) 100 m (327 ft)
DECmau 900TL 11
UTP STP
Speed Level 3 Level 5
4 Mb/s 100 m (327 ft) 200 m (655 ft) 376 m (1235 ft)
16 Mb/s 65 m (213 ft) 100 m (327 ft) 173 m (569 ft)