Overriding VRRP Configuration

About this task

A default gateway is a critical resource for connectivity. However, it's prone to a single point of failure. Thus, redundancy for the default gateway is required by the access point. If WAN backhaul is available, and a router failure occurs, then an access point should act as a router and forward traffic on to its WAN link.

Define an external VRRP (Virtual Router Redundancy Protocol) configuration when router redundancy is required in a wireless network requiring high availability.

The election of a VRRP master is central to the configuration of VRRP. A VRRP master (once elected) performs the following functions:

Responds to ARP requests
Forwards packets with a destination link layer MAC address equal to the virtual router MAC address
Rejects packets addressed to the IP address associated with the virtual router, if it is not the IP address owner
Accepts packets addressed to the IP address associated with the virtual router, if it is the IP address owner or accept mode is true

Nodes that lose the election process enter a backup state where they monitor the master for any failures. In case of a failure, one of the backups becomes the master and assumes the management of the designated virtual IPs. A backup does not respond to an ARP request, and discards packets destined for a virtual IP resource.

To define the configuration of a VRRP group:

Procedure

Select Configuration → Devices from the web UI.
The Device Configuration screen displays a list of managed devices or peer controllers, service platforms, or access points.
Select a target device in the lower left-hand side of the UI.
You can also select a target device by double-clicking it in the list in the Device Configuration screen.
Select Profile Overrides.
Select VRRP.

Note
A blue override icon (to the left of a parameter) defines the parameter as having an override applied. To remove an override go to the Basic Configuration section of the device and click Clear Overrides. This removes all overrides from the device.

Device Overrides - VRRP Screen

Review the following VRRP configuration data to assess whether a new VRRP configuration is required or whether an existing VRRP configuration can be modified or removed:


Virtual Router ID	A numerical index (from 1 - 255) used to differentiate VRRP configurations. The index is assigned when a VRRP configuration is initially defined. This ID identifies the virtual router for which a packet is reporting status.
Description	A description assigned to the VRRP configuration when it was either created or modified. The description is implemented to provide additional differentiation beyond the numerical virtual router ID.
Virtual IP Addresses	The virtual interface IP address used as the redundant gateway address for the virtual route.
Interface	The interfaces selected on the access point to supply VRRP redundancy failover support.
Priority	A numerical value (from 1 - 254) used for the virtual router master election process. The higher the numerical value, the higher the priority in the election process.

Click Add to create a new VRRP configuration.
Click Edit to modify or override the attributes of a existing VRRP configuration. If necessary, existing VRRP configurations can be selected and permanently removed by clicking Delete.
Device Overrides - VRRP - Virtual Router Screen
If you are creating a new VRRP configuration, assign a Virtual Router ID from 1 - 255.
In addition to functioning as numerical identifier, the ID identifies the virtual router for which a packet is reporting status.

Define the following VRRP General parameters:


Description	In addition to an ID assignment, a virtual router configuration can be assigned a textual description (up to 64 characters) to further distinguish it from others with a similar configuration.
Priority	Use the spinner control to set a VRRP priority setting from 1 - 254. The controller or service platform uses the defined setting as criteria in selection of a virtual router master. The higher the value, the greater the likelihood of this virtual router ID being selected as the master.
Virtual IP Addresses	Provide up to eight IP addresses representing the Ethernet switches, routers, or security appliances defined as virtual router resources.
Advertisement Interval Unit	Select either seconds, milliseconds or centiseconds as the unit used to define VRRP advertisements. After an option is selected, the spinner control becomes enabled for that Advertisement Interval option. The default interval unit is seconds. If you are changing the VRRP group version from 2 to 3, the advertisement interval must be in centiseconds. Use VRRP group version 2 when the advertisement interval is either in seconds or milliseconds.
Advertisement Interval	After an Advertisement Interval Unit is selected, use the spinner control to set the interval the VRRP master sends out advertisements on each of its configured VLANs. The default setting is 1 second.
Preempt	Select this option to ensure a high priority backup router is available to preempt a lower priority backup router resource. The default setting is enabled. When selected, the Preempt Delay option becomes enabled to set the actual delay interval for pre-emption. This setting determines if a node with a higher priority can take over all the Virtual IPs from the nodes with a lower priority.
Preempt Delay	If the Preempt option is selected, use the spinner control to set the delay interval (in seconds) for preemption.
Interface	Select this value to enable or disable VRRP operation and define the VLAN (1 - 4,094) interface where VRRP will be running. These are the interfaces monitored to detect a link failure.

Refer to the Protocol Extension field to define the following:


Sync Group	Select the option to assign a VRRP sync group to this VRRP ID‘s group of virtual IP addresses. This triggers VRRP fail over if an advertisement is not received from the virtual masters that are part of this VRRP sync group. This setting is disabled by default.
Network Monitoring: Local Interface	Select wwan1, pppoe1, and VLAN ID(s) as needed to extend VRRP monitoring to these local access point interfaces. Once selected, these interfaces can be assigned an increasing or decreasing level or priority for virtual routing in the VRRP group.
Network Monitoring: Critical Resource	Assign the priority level for the selected local interfaces. Backup virtual routers can increase or decrease their priority in case the critical resources connected to the master router fail, and then transition to the master state themselves. Additionally, the master virtual router can lower its priority if the critical resources connected to it fails, so the backup can transition to the master state. This value can only be set on the backup or master router resource, not both. Options include None, increment-priority and decrement priority.
Network Monitoring: Critical Resource Name	Select each critical resource needed for monitoring. The action specified in the Critical Resource drop-down menu is applied to each selected critical resource.
Network Monitoring: Delta Priority	Use this setting to decrement the configured priority (by the set value) when the monitored interface is down. When critical resource monitoring is enabled, the value is incremented by the setting defined.