Ri/Ro-Like Connection - Cabletron Systems SmartSTACK STS16-20RM Installation And User Manual

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RI/RO-Like Connection

Two different types of RI/RO connections are used on the UTP cables and fiber
RI/RO connections on the switch.
UTP RI/RO Connection
A UTP RI/RO connection is only available on STS16-20RM, on ports 19 and 20.
This feature allows the switch to connect to CAU/LAM systems using the RI/RO
connections thus providing a RI/RO-like functionality. This enables the switch to
be easily installed in existing Token Ring networks.
A loop-back function has been implemented on these ports so that if the port is
disabled or the switch is powered off there will not be a break in the attached main
ring. This means that attaching a cable from the RI port of a MAU port to one of
the two switch ports in effect joins the primary and the backup ring in a MAU/CAU
main ring system. Connecting the other end of the RI/RO connection to the other
switch port, creates redundant paths because the two switch ports are connected to
the same segment. Therefore, the IEEE Spanning Tree Protocol (STP) must be
enabled, which will place one port in forward and the other in blocked mode. If
there is a break in the main ring, the STP will place both ports in forward mode, and
all MACs on both segments will be relearned.
If a switch port has been configured to RI/RO mode, it will automatically sense
whether the port has been connected to RI or RO of the MAU.
Note: It is not possible to automatically verify whether an UTP/STP port has been
connected according to the configuration. Any errors, such as attaching port 19 or
20 to a normal MAU port when the STS16-20RM port has been configured for
RI/RO, will cause a complete disruption of the ring to which the port is attached.
Therefore, be careful when using the RI/RO feature.
Fiber RI/RO Connection
Fiber RI/RO is available for all twenty ports on the STS16-20FRM Switch and on
fiber expansion modules. This mode allows the switch to connect to fiber devices
that does not conform to 802.5j specifications.
SmartStack STS16-20RM/STS16-20FRM Token Ring Switches, P/N: 9032957-01 Switch Overview