Fast Root Failover Operation; Configuring Stp Globally - Siemens RX1500 User Manual

RUGGEDCOM ROX II
User Guide
NOTE
Careful network analysis and planning should inform each step of creating an MSTP network.
NOTE
MSTP does not need to be enabled to map a VLAN to an MSTI. However, the mapping must be
identical for each bridge that belongs to the MSTP region.
1. Disable STP. For more information, refer to
2. Configure one or more Multiple Spanning Tree Instances (MSTI), each with a unique bridge priority. For more
information, refer to
3. Create static VLANs and map them to the MSTIs. For more information, refer to
Static VLAN".
4. Configure the cost and priority for each switch or trunk port that will transmit/receive MST BPDU (Bridge
Protocol Data Unit) traffic. For more information, refer to
Priorities".
5. Set the STP protocol version to MSTP, configure the MST region identifier and revision level, and then
enable STP. For more information, refer to
Section 5.34.4

Fast Root Failover Operation

In mesh network topologies, the standard RSTP algorithm does not guarantee deterministic network recovery
time in the case of a root switch failure. Such a recovery time is difficult to calculate and can be different (and may
be relatively long) for any given mesh topology. This configuration parameter enables Siemens's enhancement
to RSTP, which detects a failure of the root switch and performs some extra RSTP processing steps, significantly
reducing the network recovery time and making it deterministic.
This feature is only available in RSTP mode. In MSTP mode, the configuration parameter is ignored.
In a single ring topology, this feature is not needed and should be disabled to avoid longer network recovery
times due to extra RSTP processing. The Fast Root Failover algorithm must be supported by all switches in the
network, including the root, to guarantee optimal performance. However, it is not uncommon to assign the root
role to a switch from a vendor different from the rest of the switches in the network. In other words, it is possible
the root might not support the Fast Root Failover algorithm. In such a scenario, a relaxed algorithm should be
used, which tolerates the lack of support in the root switch.
Section 5.34.5

Configuring STP Globally

To configure global settings for the Spanning Tree Protocol (STP), do the following:
1. Change the mode to Edit Private or Edit Exclusive.
2. Navigate to switch » spanning-tree. The Spanning Tree, eRSTP and RSTP (Common) Instance forms
appear.
Fast Root Failover Operation
Section 5.34.5, "Configuring STP
Section 5.34.8.3, "Adding a Multiple Spanning Tree
Section 5.34.5, "Configuring STP Globally"
Globally".
Instance".
Section 5.34.9, "Managing Port Costs and
Chapter 5
Setup and Configuration
Section 5.35.4.2, "Adding a
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