Hrp - Siemens SCALANCE XM-400 Configuration Manual

Technical basics
4.6 Redundancy mechanism
● Alternate port (substitute for the root port)
A substitute for the root port is configured. If the connection to the root bridge is lost, the
device can establish a connection over the alternate port without any delay due to
reconfiguration.
● Reaction to events
Rapid spanning tree reacts to events, for example an aborted connection, without delay.
There is no waiting for timers as in spanning tree.
● Counter for the maximum bridge hops
The number of bridge hops a package is allowed to make before it automatically becomes
invalid.
In principle, therefore with rapid spanning tree, alternatives for many parameters are
preconfigured and certain properties of the network structure taken into account to reduce the
reconfiguration time.
Multiple Spanning Tree Protocol (MSTP)
The Multiple Spanning Tree Protocol (MSTP) is a further development of the Rapid Spanning
Tree Protocol. Among other things, it provides the option of operating several RSTP instances
within different VLANs or VLAN groups and, for example, making paths available within the
individual VLANs that the single Rapid Spanning Tree Protocol would globally block.
Common and Internal Spanning Tree (CIST)
CIST identifies the internal instance used by the switch that is comparable in principle with an
internal RSTP instance.
4.6.2

HRP

HRP - High Speed Redundancy Protocol
HRP is the name of a redundancy method for networks with a ring topology. The switches are
interconnected via ring ports. One of the switches is configured as the redundancy manager
(RM). The other switches are redundancy clients. Using test frames, the redundancy manager
checks the ring to make sure it is not interrupted. The redundancy manager sends test frames
via the ring ports and checks that they are received at the other ring port. The redundancy
clients forward the test frames.
If the test frames of the RM no longer arrive at the other ring port due to an interruption, the
RM switches through its two ring ports and informs the redundancy clients of the change
immediately. The reconfiguration time after an interruption of the ring is a maximum of 300 ms.
Standby redundancy
Standby redundancy is a method with which rings each of which is protected by high-speed
redundancy can be linked together redundantly. In the ring, a master/slave device pair is
configured and these monitor each other via their ring ports. If a fault occurs, the data traffic
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SCALANCE XM-400/XR-500 Web Based Management (WBM)
Configuration Manual, 05/2017, C79000-G8976-C248-12