Allied Telesis AT-MR420T, Installation Manual

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Topology
22
MDI/MDI-X Switch and Uplink Port
While any RJ45 port can be used to cascade repeaters, port 4/8 has
been specifically designed with an uplink (cascading) capability, by
providing a Media Dependent Interface (MDI/MDI-X) switch.
Cascading through port 4/8 means if a single, standalone AT-MR420T/
AT-MR820T Micro Repeater can support 4/8 ports, when a second
AT-MR420T/AT-MR820T Micro Repeater is uplinked (cascaded) using
the port 4/8 of the first unit to any port of a second unit. A maximum of
four repeaters (the four repeater rule) can be interconnected. The
network effectively consists of 6 nodes for the AT-MR420T and 14
nodes for the AT-MR820T. The Uplink port is located on the back
panel, as shown in Figure 13.
Figure 13: Uplink Port
Port 4/8 has the ability to become a dedicated uplink port. To facilitate
this process, it uses a Media Dependent Interface (MDI/MDI-X) switch.
An MDI/MDI-X switch is a crossover/straight-through cable selection
slide switch. As shown in Figure 13, the MDI/MDI-X switch converts
the 10Base-T (RJ45) Port 4/ 8, to an uplinkable port that allows one
repeater to connect to another repeater without requiring special
crossover cables.
MRx20T(UTP)Ver6_Book Page 22 Thursday, April 3, 1997 5:18 PM