EnGenius EWS Series User Manual page 106

Loops occur when alternate routes exist between hosts. Loops in an extended network can cause the
Switch to forward traffic indefinitely, resulting in increased traffic and reducing network efficiency. Once
the STP is enabled and configured, 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
Multiple Spanning Tree Protocol (MSTP) defined in IEEE 802.1s, enables multiple VLANs to be mapped to
reduce the number of spanning-tree instances needed to support a large number of VLANs. If there is
only one VLAN in the network, a single STP works appropriately.
If the network contains more than one VLAN however, the logical network configured by a single STP
would work, but it becomes more efficient to use the alternate paths available by using an alternate
spanning tree for different VLANs or groups of VLANs. MSTP (which is based on RSTP for fast
convergence) is designed to support independent spanning trees based on VLAN groups. MSTP provides
multiple forwarding paths for data traffic and enables load balancing.
STP and RSTP prevent loops from forming by ensuring that only one path exists between the end nodes
in your network. RSTP is designed as a general replacement for the slower, legacy STP. RSTP is also
incorporated into MSTP. With STP, convergence can take up to a minute to complete in a larger network.
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