User's Manual

CHAPTER 7
REPEATING FEATURES
Revised: 5 Dec 12 7-3 EST P/N AA107-210CM
RAPID SPANNING TREE PROTOCOL (RSTP)
The ESTeem Model 210 uses Rapid Spanning Tree Protocol (RSTP - IEEE 802.1d) to determine the radio routing structure of the
wi
rel
ess network. This RSTP functions the same as standard Spanning Tree Protocol (STP) listed below, but the network
recovery is three times faster. If the 210 is used in a network that has any older STP only modems, the entire network will be STP.
SPANNING TREE PROTOCOL (STP)
The ESTeem Model 210 uses standard Ethernet Spanning Tree Prot
ocol
(STP) or Rapid Spanning Tree Protocol (RSTP) to
determine the radio routing structure of the wireless network. The primary purpose of STP/RSTP is to make sure that “network
loops” are not created. A network loop is having two communication paths to the same destination where the remote device would
receive the same data multiple times. If there were no way to control the data flow, this data would be constantly passed around
this loop causing a “packet storm” that would shut down the entire network. The Spanning Tree Protocol will block all these
redundant links.
The STP operation begins by determining which Ethernet device on the network will be the Root Bridge. All Ethernet networks
have a Root
Bridge that is selected by the lowest MAC address. All path costs are evaluated against this Root Bridge device to
determine routing and which paths will be blocked. On a wired Ethernet network, the location of the Root Bridge is not really
Figure 3: Programming Example #1 Diagram