Iqos; Forced Roaming On Ip Down; Link Check; Redundancy - Siemens SCALANCE W786-xPRO Operating Instructions Manual

Configuration / project engineering
5.1 Technical basics
5.1.2

iQoS

Client-specific bandwidth reservation
iQoS (Quality of Service) is technique with which clients are assigned a certain bandwidth.
Due to this assignment, there is a high probability that data transmission to these clients will
be within a defined period. This technique can be useful when response times must be
guaranteed.
5.1.3

Forced Roaming on IP Down

Functional description
"Forced Roaming on IP down" monitors the connection to a specific IP address cyclically.
This is achieved using ICMP packets (Echo Request/Reply or Ping). If the IP connection
aborts; in other words, there is no ping reply from the other end, a deauthentication frame is
sent to all WLAN clients. The relevant WLAN interface is then disabled.
The IP connection continues to be monitored and the WLAN interface is enabled again as
soon as the access point has received a ping reply from the pinged station.
The mechanism makes it possible, for example, to monitor a connection between wireless
clients and a server. If the server can no longer be reached over the access point, the clients
are deauthenticated and the WLAN interface of the access point is disabled. The clients
roam and then connect to a different access point from which the server can be reached. As
soon as the first access point can reach the server again, it re-enables its WLAN interfaces.
5.1.4

Link Check

Device-related connection monitoring
The Link Check function provides device-related connection monitoring for a maximum of ten
wireless nodes logged on at the SCALANCE W78x. This service can be compared with the
link on a wired connection. The function monitors whether the node is available over the
wireless medium. If no packet is received from the node or sent successfully after half of the
configured monitoring time, the SCALANCE W78x attempts to send a test packet to the
node.
5.1.5

Redundancy

Redundant connection between two SCALANCE W78x devices
You can configure two SCALANCE W78x devices with two wireless interfaces so that there
is a redundant wireless connection. The redundancy function causes an automatic failover to
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Operating Instructions, Release 08/2007, C79000-G8976-C221-02
SCALANCE W786-xPRO