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Routing
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 Connect EZ 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 Connect EZ 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 Connect EZ devices,
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 Connect EZ device.
Required configuration items
Enable VRRP.
n
The interface used by VRRP.
n
The Router ID that identifies the virtual router instance. The Router ID must be the same on all
n
VRRP devices that participate in the same VRRP device pool.
The VRRP priority of this device.
n
The shared virtual IP address for the VRRP virtual router. Devices connected to the LAN will use
n
this virtual IP address as their default gateway.
See
Configure VRRP+
network probing to monitor connections through VRRP-enabled devices and dynamically change the
VRRP priorty of devices based on the status of their network connectivity.
WebUI
Digi Connect EZ 4/4i User Guide
for information about configuring VRRP+, an extension to VRRP that uses
Virtual Router Redundancy Protocol (VRRP)
SureLink
is used to
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