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As promised on the ad hoc call, here is my understanding of Stefan Buntz’s multidrop topologies: Assume: ‘head node’ is as discussed in EPON – this is the node that controls the multipoint protocol. All other nodes are clients. Passive Linear: Stub length < 100mm Overall length, including < 25m Minimum spacing between nodes: 500mm Maximum spacing between nodes: 7900mm (8 m including 2 100mm stubs) Maximum number of nodes: 8 (including head node) No other constraints on node placement (no constraint on granularity) David Brandt variation for industrial: 45mm shortest between nodes on linear topology.
Questions:
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Does minimum spacing include the stub lengths?
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It appears from slide 4 that there may be minimums on overall length (8m) and stub length (50mm) – is this true?
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Would a terminator be placed at the far-end, or at the head-node?
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Is the ‘head node’ always at one end? Passive Star: Head stub length (head node to passive star center) < 100mm Maximum star branch length – 7900m (8m including head-node stub) Minimum star branch length – 1000mm Maximum number of nodes – 8 (including head node) One node per branch No constraint on the granularity of branch length Questions: Is the minimum head stub length > 50mm Maximum total cable length – is this constrained? 7900 x 7 + 100 = 55400 mm (~55m) – is this correct? Placement of termination – at head end, distributed, or on one end of a linear What MDI return loss might be assumed at the branch ends? (100BASE-T1?) George Zimmerman, Ph.D. President & Principal CME Consulting, Inc. Experts in Advanced PHYsical Communications 310-920-3860 |