You can use the lobe port on an IBM 8238 Fiber or Copper RI/RO Feature to attach the stack to a backbone ring.
The below illustration show physical and logical diagramsof the backbone ring attachement. The physical diagram shows a
Fiber RI/RO Feature. However, you can connect the Copper RI/RO Feature using the same method.
To attach the hub stack to a backbone ring:
Use the SET HUB RIRO_MODE ISOLATED mgmt. command to isolate the RI/RO Feature from
the main stack ring (token_ring_1). For example: