IBM 8230 Controlled Access Unit

The IBM 8230 Controlled Access Unit Models 003, 013, and 213 are intelligent, Token-Ring workgroup concentrators that provide flexible connectivity for anywhere from 2 to 92 devices (operating at 4 or 16 Mbps) on a token-ring network. The IBM 8230 Controlled Access Unit Models 04A and 04P are suitable for a variety of environments in which low-end token-ring concentration is required.
Mix and match media support (Models 3, 13 and 213).

Plug-in Lobe Insertion Units (LIUs) grow networks in 2, 3 or 4 port increments (Models 3, 13 and 213).

Lobe Attachment Modules (LAMs) extend base unit connectivity (Models 3, 13 and 213).

Dual Ring Redundancy feature automatically recovers from breaks in the ring media (Models 3, 13 and 213).

Active ports for reliable connections over long distances, or passive ports where active ports are not required.

Ring-In/Ring-Out modules connect workgroups backbone rings with either copper or fiber.

Fully interoperable with products that comply with IEEE 802.5 standards.

Failing ring segments are automatically disconnected.

Automatic speed detect assures correct speed attachment speed without operator intervention.

SNMP-based (including RMON) and OSI-based (CMOL) graphical management applications.

— networking.ibm.com