Digi TX54, User Manual

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Routing Virtual Router Redundancy Protocol (VRRP)
TX54 User Guide 375
(config network ddns new_ddns_instance)> retry_interval 600s
(config network ddns new_ddns_instance)>
The default is 60s .
13. (Optional) Set the number of times to retry a failed IP address update:
(config network ddns new_ddns_instance)> retry_count value
(config network ddns new_ddns_instance)>
where value is any interger. The default is 5 .
14. Save the configuration and apply the change:
(config)> save
Configuration saved.
>
15. Type exit to exit the Admin CLI.
Depending on your device configuration, you may be presented with an Access selection
menu . Type quit to disconnect from the device.
Virtual Router Redundancy Protocol (VRRP)
Virtual Router Redundancy Protocol (VRRP) is a standard for gateway device redundancy and failover
that creates a "virtual router" with a floating IP address. Devices connected to the LAN then use this
virtual router as their default gateway. Responsibility for the virtual router is assigned to one of the
VRRP-enabled devices on a LAN (the "master router"), and this responsibility transparently fails over
to backup VRRP devices if the master router fails. This prevents the default gateway from being a
single point of failure, without requiring configuration of dynamic routing or router discovery
protocols on every host.
Multiple TX54 devices can be configured as VRRP devices and assigned a priority. The router with the
highest priority will be used as the master router. If the master router fails, then the IP address of the
virtual router is mapped to the backup device with the next highest priority. Each VRRP router is
configured with a unique LAN IP address, and the same shared VRRP address.
VRRP+
VRRP+ is an extension to the VRRP standard that uses network probing to monitor connections
through VRRP-enabled devices and can dynamically change the priority of the devices, including
changing devices from master to backup, and from backup to master, even if the device has not
failed. For example, if a host becomes unreachable on the far end of a network link, then the physical
default gateway can be changed by adjusting the VRRP priority of the TX54 device connected to the
failing link. This provides failover capabilities based on the status of connections behind the router, in
addition to the basic VRRP device failover. For TX54 devices,
SureLink is used to probe network
connections.
VRRP+ can be configured to probe a specified IP address by either sending an ICMP echo request
(ping) or attempting to open a TCP socket to the IP address.
Configure VRRP
This section describes how to configure VRRP on a TX54 device.