Specifications

A.11 FDDI Tree Configuration Examples
FDDI Configuration Capabilities A–17
A.11 FDDI Tree Configuration Examples
The DEChub 900 backplane supports many types of FDDI tree configurations. FDDI
trees can be contained within the hub backplane and can connect an individual tree in
the hub backplane to a higher level of a tree, or can be used to interconnect other
hubs.
This section provides five examples of FDDI tree configurations that are supported
in the DEChub 900 backplane:
• Example 1 — Self-contained Tree of Concentrators in Hub Backplane
• Example 2 — Self-contained Tree of Switches and Concentrators in Hub Back-
plane
• Example 3 — Tree Connections to an External Concentrator
• Example 4 — Dual Homing and Connection to an External Ring
• Example 5 — FDDI Tree Extensions
A.11.1 Example 1 — Self-contained Tree of Concentrators in Hub Back-
plane
In this example (see Figure A-10), an FDDI tree is constructed entirely within the
Hub backplane. The backplane ports of the concentrator modules are enabled as M
ports and S ports. The front panel ports become M ports.
The module that is installed in the highest slot number of the Hub (Concentrator 3) is
designated as the top of the tree, and its M port connects to the S port of the module
with the second highest slot number (Concentrator 2).
Two Hub backplane channels are required for each connection. In Figure A–10, a
total of four backplane channels are in use.