Andrew SmartLine 16, Руководство пользователя

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Introduction
1-2
SmartLine 16 User’s Guide
corrected, the ring is automatically switched back to the primary
ring.
SmartLine 16s share the same out-of-band network manager as its
cousin the SmartLine 8122. You can intermix a stack of up to eight
SL16s and/or SL8122s and manage them all with a PC console
connected to the serial port of the first unit. You can connect the PC
management console either directly to the first unit in a stack or
operate the console remotely by using a dial-up modem.
The SmartLine Manager software is a Windows-based GUI
(Graphical User Interface) program that can present a front panel
graphic for each unit in the stack. This gives the manager a view of
the front panel LED status and switch settings. It also allows you to
control ring access and enable/disable speed detection on individual
lobe ports.
1.2 Token Ring Theory
Token Ring LANs adhere to the IEEE 802.5 standard. Briefly stated,
each workstation connected must pass a data packet, called a token,
received from an upstream workstation to the next downstream
workstation. Because the workstations connect in a ring or loop,
tokens pass through all active workstations. Also, because each
workstation retransmits the token, transmission line losses do not
limit cable lengths to the extent they do in other LAN configurations.
Because tokens move in only one direction, collision of packets is
not a concern.
All workstations connected to a Token Ring LAN require an adapter
card in one of the expansion slots of the workstation. Each adapter
card can recognize tokens, transmit data, generate tokens, and detect
faults. For the purpose of error recovery, one adapter card acts as the
Active Token Monitor. Should this card fail to operate, the error
recovery chore passes to another adapter card.
Token frames contain fields for starting and ending delimiters,
source and destination addresses, data, and data checking. The
ending delimiter contains a token bit that indicates whether or not the