Siemens DataNET Hub (DNH) user manual DataNET Hub Hierarchy, Ethernet Bridging

Overview, Continued

DataNET Hub Hierarchy

A network of DataNET hubs forms a tree-like hierarchy. A DNH may connect to as many as eight “down-stream” devices (Maxum Analyzers or Advance Hub Uplink port). Each down-stream DNH, in turn, connects to another eight, and so on. No architectural limit is placed on the depth of the DataNET hub hierarchy. In practice, propagation time considera- tions and hub loading should allow hierarchies at least six or seven lay- ers deep without incurring excessive timing delays.

Figure 1-2. DataNET Hub Hierarchy

DataNET hub

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DataNET hub

Ethernet

DataNET hub

DataNET hub

DataNET hub
DataNET hub	DataNET hub

DataNET hub

Ethernet Bridging

Figure 1-3 illustrates two separate trees of DataNET hubs that share an Ethernet segment.

A hub can also connect to-and-from an Ethernet device or an Ethernet compatible Advance Network Gateway (ANG) unit or to and from a non- redundant Ethernet connection. A tree of DataNET hubs can function as an Ethernet bridge, transparently connecting all the Ethernet segments that are attached at any point on the hierarchy. The DataNET hub soft- ware does not implement any software protocols (e.g. IEEE 802.1 span- ning tree) to prevent routing loops. Thus, each tree of DataNET hubs may connect to any Ethernet segment at exactly one point. Multiple Da- taNET trees may share Ethernet links.

Figure 1-3. Ethernet

Bridging

Ethernet	DataNET hub
	Ethernet

DataNET hub

	DataNET hub
	DataNET hub
Ethernet	DataNET hub
	DataNET hub

DataNET hub

Ethernet

DataNET hub

DataNET hub

2000585-001 Introduction • 3