Allied Telesis AT-MR820TR CentreCOM 8-Port Ethernet External Stackable Hub

The CentreCOM Micro Hubs are twisted pair hubs intended to connect as many as eight IEEE 802.3 10Base-T network segments through one unit. Each hub has one twisted pair port specifically designed with an uplink (cascading) capability supporting a Media Dependent Interface (MDI/MDI-X) crossover switch. As many as four hubs can be cascaded together to form an independent workgroup containing as many as 26 nodes. To form an independent workgroup, the micro hubs are equipped with a Backbone Enable/Disable Switch to separate (or reconnect) all connected or cascaded nodes from the backbone ports. The CentreCOM Micro Hubs also contain two additional ports for attachment to the Local Area Network (LAN) backbone. One such port is configured with an Attachment Unit Interface (AUI), which with an external transceiver can provide attachment to thick coax, twisted pair or fiber optic media. The other port is configured with a Bayonet Nut Couple (BNC) connection for direct attachment to thin coax media. Either port may be selected manually with a Media Select Switch.

These micro hubs utilize the latest IC and Surface Mount Technology (SMT), which increase functionality and reliability. Additionally, these hubs are small in size, yet they provide the complete functionality of large hubs including packet regeneration and network partitioning. The packet regeneration results in a higher performance network by regenerating preamble, retiming the data packets and extending collision fragments to ensure collision enforcement by all nodes. Each segment automatically detects the polarity of the receive pair and reverses should the pair be incorrectly installed. The IEEE - defined link integrity test function continually monitors the receive pair to ensure link continuity. It also includes a partitioning capability where each segment automatically disconnects itself after repeated collisions are detected. The hubs supports jabber lock-up protection on all interfaces, preventing transceiver lock-up resulting from packets that exceed the maximum packet length.