Digi TransPort WR31 User Manual page 161

Configure network interfaces
Enable VRRP+ Probing
Enables VRRP+ probing on this Ethernet interface. VRRP with probing differs from standard
VRRP in that it dynamically adjusts the VRRP priority of an interface and if necessary, changes
the status of that interface from master to backup or vice-versa. It does this by probing an
interface, either by sending an ICMP echo request (PING) or by attempting to open a TCP socket
to the specified Probe IP address. Therefore, VRRP operation is enhanced to ensure a secondary
router can take over under a wider range of circumstances.
Send p probe to IP address a.b.c.d TCP port n
Configures VRRP+ to send a probe packet to desired IP address and TCP port. The TCP port is
needed if the probe type is TCP. The routing code determines which interface to use. This allows
the router to test other interfaces and adjust the VRRP priority according to the status of that
interface. For example, the user may wish to configure probing in such a way that the Digi router
WAN interface is tested, and adjust the VRRP priority down if the WAN is not operational. Another
example would be to probe the WAN interface of another VRRP router, and adjust the local VRRP
priority up if that WAN interface is not operational. When configured to probe in this manner, it is
necessary to configure a second Ethernet interface to be on the same subnet as the VRRP
interface. This is because you cannot use the VRRP interface when it is in backup mode. The
probes should be sent on this second interface. The second interface has the other VRRP router
as its gateway. Configure the routing table to direct packets for the probe address to the desired
interface.
every n seconds when in Backup state
The interval between successive probe attempts when the interface is in Backup state.
every n seconds when in Master state
The interval between successive probe attempts when the interface is in Master state.
Adjust priority n dir after x probe failures
Controls by how much and in which direction the VRRP priority is adjusted when the specified
number of probes have failed.
Reset probe failure count after n probe successes
The number of consecutive successful probes required before the current failure count is reset
to 0.
Digi TransPort WR Routers User Guide
Configure Ethernet interfaces
161