Specifications

RADring
Installation & Operation Manual Functional Description
3/11/98 12:33 Access Modules Functional Description 2-17
2.7 Access Modules Functional Description
TL-4 Four-port
Lobe Access
Modules
The TL-4 lobe access modules include four independent lobe interfaces,
enabling attachment of four stations to the ring. Each lobe circuit is
normally in bypass unless the attached station requests insertion into the
ring. The lobe circuit remains in bypass if the station is inactive, to indicate
that the lobe cable is disconnected or there is a cable fault. Under
RADview Network Management the bypass state can also be
independently controlled. Status indicators are provided for module power,
to indicate that at least one port is under management, and to each port to
indicate inserted/bypassed status.
The TL-4 lobes do not require resetting upon installation. Each module is
completely independent of the modules preceding or following it, enabling
hot insertion or removal of the module from the ring, unless the module has
been set to TERMINATE.
The TL-4 module can be configured as a terminating card to provide ring
separation between two adjacent modules. When the module is positioned
as the (furthest right) end card of a lobe's module group (and is configured as
the terminating card), it isolates the module group from the other lobe
access modules on its right to establish ring separation. If, in this instance, the
terminating module is removed, the two module groups join together to
form a single module group.
The phantom circuit for the TL-4 module has an operating voltage of 4.5
±0.6V, and an operating current of 1.0 mA @ 5.0 V. The DC resistance from
transmit to receive is 5.00 ±0.15 kΩ, while both the insertion and removal
time is 5 msec for each lobe.
TL-4/A Active Access Modules
TL-4/AS, TL-4/ASD, TL-4/AU, TL-4/ASU and TL-4/CX lobe circuits are active
with regard to the Token Ring signal, with the exception of the TL-4/CX. The
IEEE 802.5 signal is regenerated in the direction of the station with clock
extraction at each lobe interface, in accordance with the IEEE 802.5 draft for
active retiming lobes. The TL-4/A modules ensure added reliability by
providing bit match detection and correction. If an interface card, set to the
incorrect speed (4/16 Mbps) with respect to the rest of the network, attempts
to insert into the network, it will be automatically bypassed. This ensures
continuous network operation. The TL-4/CX transmits the signal over a
coaxial cable without retiming. At the station end of the TL-4/CX module, a
TXC balun must be used to allow connection of the coaxial cable to the
interface card (NIC).