Siemens SCALANCE X320-3LD FE Operating Instructions Manual page 312

Appendix
A.1 TP port
Autonegotiation
Autonegotiation means the automatic detection of the functionality of the port at the opposite
end. Using autonegotiation, network components or end devices can detect the functionality
available at the port of a partner device allowing automatic configuration of different types of
device. With autonegotiation, two components connected to a link segment can exchange
parameters and set themselves to match the supported communication functionality.
Note
With devices that do not support autonegotiation, the IE Switch X-300 port must be set
manually to the speed and duplexity settings of the device (in other words, the identical
setting).
Note
The IE Switch X-300 is a plug-and-play device that does not require settings to be made for
commissioning.
MDI /MDIX autocrossover function
The advantage of the MDI /MDIX autocrossover function is that straight-through cables can
be used throughout and crossover Ethernet cables are unnecessary. This prevents
malfunctions resulting from mismatching send and receive wires. This makes installation
much easier for the user.
The IE Switches X-300 all support the MDI / MDIX autocrossover function.
Note
Autocrossover works only in autonegotiation is enabled. If the setting is fixed, there is no
autocrossover (see Glossary).
Note
Please note that a direct connection between two ports on the IE Switch X-300 or an
accidental connection over several IE Switches X-300 can cause illegal formation of loops
unless RSTP or STP is activated. Such a loop can lead to network overload and network
failures.
312
Operating Instructions, 05/2016, A5E01113043-20
SCALANCE X-300