Cisco SG550XG-24F - STP Status and Global Settings

Spanning Tree
STP Status and Global Settings
223 Cisco Sx350, SG350X, SG350XG, Sx550X & SG550XG Series Managed Switches, Firmware Release 2.2.5.x
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The device supports the following Spanning Tree Protocol versions:
• Classic STP – Provides a single path between any two end stations, avoiding and
eliminating loops.
• Rapid STP (RSTP) – Detects network topologies to provide faster convergence of the
spanning tree. This is most effective when the network topology is naturally tree-
structured, and therefore faster convergence might be possible. RSTP is enabled by
default.
• Multiple STP (MSTP) – MSTP is based on RSTP. It detects Layer 2 loops, and
attempts to mitigate them by preventing the involved port from transmitting traffic.
Since loops exist on a per-Layer 2-domain basis, a situation can occur when a port is
blocked to eliminate a STP loop. Traffic will be forwarded to the port that is not
blocked, and no traffic will be forwarded to the port that is blocked. This is not an
efficient usage of bandwidth as the blocked port will always be unused.
• MSTP solves this problem by enabling several STP instances, so that it is possible to
detect and mitigate loops separately in each instance. This enables a port to be blocked
for one or more STP instances but non blocked for other STP instances. If different
VLANs are associated with different STP instances, then their traffic will be relayed
based on the STP port state of their associated MST instances. Better bandwidth
utilization results.
STP Status and Global Settings
The STP Status and Global Settings page contains parameters for enabling STP, RSTP, or
MSTP.
Use the STP Interface Settings page, RSTP Interface Settings page, and MSTP Properties page
to configure each mode, respectively.
To set the STP status and global settings:
STEP 1 Click Spanning Tree > STP Status & Global Settings.
STEP 2 Enter the parameters.
Global Settings:
• Spanning Tree State—Select to enable on the device.
• STP Loopback Guard—Select to enable Loopback Guard on the device.
• STP Operation Mode—Select an STP mode.