Wavetronix Click 342 (lean managed ethernet switch) (CLK-342) - Managed Switches User Guide - Manual (Page 61)

60 CHAPTER 6 • RAPID SPANNING TREE
A data path can also be a connection of a Spanning Tree switch to:
˽ A termination device.
˽ A network segment in which no loops may occur, which consists of several infrastruc-
ture components (hubs or switches) without Spanning Tree support.
Notes on Rapid Spanning Tree
The following rules regarding Spanning Tree must be observed:
1 Spanning Tree transparency for all infrastructure components – All infrastructure
components used in your network that do not actively support Spanning Tree must be
transparent for Spanning Tree messages (BPDUs) and must forward all BPDUs to all
ports without modifying them. When Spanning Tree is disabled, the switch is transpar-
ent for BPDUs.
2 At least one active Spanning Tree component per loop – An active Spanning Tree
component supports the Spanning Tree Protocol, sends/ receives and evaluates BP-
DUs, and sets its ports to the relevant STP states. Each loop in a network must have at
least one active Spanning Tree component to disintegrate the loop.
Example: The example topology below contains six loops (see Figure 6.7). Each of these
loops contains active STP components, e.g., device 4 and device 2. In this way, all loops are
broken by STP.
Figure 6.7 – Example Topology
3 No more than 10 active Spanning Tree components in the topology when using
Spanning Tree default settings – The ability to disintegrate any topology to form a
tree without loops requires a complex protocol that works with several variable tim-
ers. These variable timers are dimensioned using IEEE standard default values so that
a topology with a maximum of ten active Spanning Tree components always results in
a stable network.
In the examples below, two network segments are connected via redundant data paths (see
Figure 6.8 and 6.9). Two STP components have ports in the Blocking state (highlighted in