Siemens DataNET Hub (DNH) - Manual (Page 11)

2000585-001 Introduction •••• 3
Overview, Continued
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.
DataNET hub
DataNET hub
DataNET hub
DataNET hub
DataNET hub
DataNET hub DataNET hub G
DataNET hub
Ethernet
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.
DataNET hub
DataNET hub
DataNET hub
DataNET hub
DataNET hub
Ethernet
Ethernet
Ethernet
DataNET hub
DataNET hub
DataNET hub
DataNET hub
Ethernet
DataNET Hub
Hierarchy
Figure 1-2. DataNET Hub
Hierarchy
Ethernet Bridging
Figure 1-3. Ethernet
Bridging