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CONFIGURATION
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4.7. VRRP Configuration
To enter the VRRP configuration select the VRRP menu item. VRRP protocol (Virtual
Router Redundancy Protocol) is a technique, by which it is possible to forward routing from
main router to backup router in the case of the main router failure. If the Enable VRRP is
checked, then it is possible to set the following parameters. Parameter Virtual Server IP
Address sets virtual server IP address. This address should be the same for both routers.
A connected device sends its data via this virtual address. Parameter Virtual Server ID
distinguishes one virtual router on the network from others. This implies that the main and
backup routers must use the same value for this parameter. The router, with higher priority
set by the parameter Host Priority, is the main router. According to RFC 2338 the main router
has the highest possible priority - 255. The backup router has priority in range 1 – 254 (init
value is 100). The priority value equals 0 is not allowed.
It is possible to set Check PPP connection flag in the second part of the window.
The currently active router (either main or backup) will send testing messages to defined
Ping IP Address at periodic time intervals (Ping Interval) with setting time of waiting for
answer (Ping Timeout). The function check PPP connection is used as a supplement of
VRRP standard with the same final result. If there are no answers from remote devices (Ping
IP Address) for a defined number of probes (Ping Probes), then connection is switched to the
other line. It is possible to use for example a DNS server of mobile operator as a test
message (ping) IP address. There's an additional way for evaluating the state of the active
line. It is activated by selecting Enable traffic monitoring parameter. If this parameter is set
and any packet different from ping is sent to the monitored line, then any answer to this
packet is expected for Ping Timeout. If Ping Timeout expires with no answer received then
process of testing the active line continues the same way like in the case of standard testing
process after first test message answer drops out.