Siemens 6GK5204-0BA00-2KB2, Руководство по эксплуатации, Страница: 20 / 176

The SCALANCE X-200RNA can manage a maximum of 1023 MAC addresses.
Note
Keep to the maximum permitted cable lengths of the devices you are using. You will find the
permitted cable lengths in the technical specifications.
Example
Figure 4-1 Schematic diagram of the "Parallel Redundancy Protocol"
With the "Parallel Redundancy Protocol" (PRP), each node must transmit Ethernet frames on two
independent, parallel networks. These are two physically separate networks with a bus (linear),
star or ring topology. The PRP destination device must also be connected to the two networks.
This then receives each frame twice. The first frame is forwarded to the application. The second
frame received is recognized and discarded. This achieves N-1 redundancy without
reconfiguration (= bumpless switchover).
Note
Overlong frames
When a SCALANCE X204RNA IE switch feeds a frame with the maximum length into a PRP
network, the IE switch appends a PRP trailer to the frame. 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.
You will find a list of compatible devices that support processing of overlong frames in the
section "PRP-compatible devices (Page 155)".
Network topologies and redundancy
4.1 PRP
SCALANCE X-200RNA
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Operating Instructions, 04/2022, C79000-G8976-C342-07