Parallel Redundancy Protocol; Vlan - Siemens SCALANCE XB-200 Configuration Manual

Technical basics

4.5 VLAN

For a redundant link as shown in the figure, two devices must be configured as standby
redundancy switches within a network segment. In this case, network segments are rings
with a redundancy manager. Instead of rings, network segments might also be linear.
The two standby redundancy switches connected in the configuration exchange data frames
with each other to synchronize their operating statuses (one device is master and the other
slave). If there are no problems, only the link from the master to the other network segment
is active. If this link fails (for example due to a link-down or a device failure), the slave
activates its link as long as the problem persists.
4.4.5

Parallel Redundancy Protocol

Parallel Redundancy Protocol
The "Parallel Redundancy Protocol" (PRP) is a redundancy protocol for Ethernet networks. It
is defined in Part 3 of the IEC 62439 standard. This redundancy method allows data
communication to be maintained without interruption/reconfiguration time if there are
interruptions in the network.
The PRP method is supported, for example, by the devices of the SCALANCE X-200RNA
product line.
Overlong frames
When sending PRP frames, the IE switch expands the frame with a PRP trailer. With frames
with the maximum length, appending the PRP trailer results in an overlong frame that
exceeds the maximum permitted frame length (according to the IEEE 802.3 standard).
To prevent data loss with overlong frames, all network components located in a PRP
network must support a frame length of at least 1528 bytes.
The devices described in this manual can be used in PRP networks, see also section
"Configuration limits (Page 19)".
4.5 VLAN
Network definition regardless of the spatial location of the nodes
VLAN (Virtual Local Area Network) divides a physical network into several logical networks
that are shielded from each other. Here, devices are grouped together to form logical groups.
Only nodes of the same VLAN can address each other. Since multicast and broadcast
frames are only forwarded within the particular VLAN, they are also known as broadcast
domains.
The particular advantage of VLANs is the reduced network load for the nodes and network
segments of other VLANs.
32
SCALANCE XB-200/XC-200/XP-200 Web Based Management
Configuration Manual, 07/2016, C79000-G8976-C360-04