Operation Manual

89
Spanning Tree Loops
Loops occur when alternate routes exist between hosts.
Loops in an extended network can cause the Switch
toforwardtrafcindenitely,resultinginincreased
trafcandreducingnetworkefciency.OncetheSTP
isenabledandcongured,primarylinksareestablished
and duplicated links are blocked automatically. The
reactivation of the blocked links is also accomplished
automatically. STP provides a tree topology and other
Spanning tree versions supported include STP, Multiple
Spanning Tree Protocol (MSTP), and Rapid Spanning Tree
Protocol (RSTP). Please note that only one spanning
tree can be active on the Switch at a time. The default
setting is: RSTP.
STP: Select whether to Enable or Disable the
spanning tree operation on the Switch.
Force Version:
Select the Force Protocol Version parameter
for the Switch.
• STP (Spanning Tree Protocol) - IEEE
802.1D.
• RSTP (Rapid Spanning Tree Protocol) - IEEE
802.1w.
• MSTP (Multiple Spanning Tree Protocol) -
IEEE 802.1s.
Once a stable network topology has been established,
all bridges listen for Hello Bridge Protocol Data Units
(BPDUs) transmitted from the Root Bridge of the
Spanning Tree. If a bridge does not receive a Hello BPDU
afterapredenedinterval(knownastheMaximumAge),
the bridge will assume that the link to the Root Bridge
is down and unavailable. This bridge then initiates
negotiationswithotherbridgestorecongurethe
network to reestablish a valid network topology.