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IP SLA Tab

Configuration > Templates & Policies > TCAs > IP SLA

Using a polling process, IP SLA (Internet Protocol Service Level Agreement) tracking provides the ability to generate specific actions in the network that are completely dependent on the state of an IP interface or tunnel. The goal is to prevent black-holed traffic. For example, associated IP subnets could be removed from the subnet table, and also from subnet sharing, if the LAN-side interfaces on an appliance go down.

This tab displays all of the IP SLA rules configured on the selected appliances. To add or modify rules, click the edit icon to the left of any row in the table.

IP SLA Monitor Use Cases

The following examples describe five basic use cases for IP SLA monitoring.

Example #1 – Ping via Interface

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  • Two passthrough tunnels configured for Internet breakout and High Availability.

  • If the Primary passthrough tunnel goes down, traffic goes to Backup tunnel.

  • The IP SLA Rule would look like this, with the same tunnel specified for the Down and Up Actions.

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Example #2 – HTTP/HTTPS via Interface

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  • Two passthrough tunnels configured for Internet breakout and High Availability.

  • If the Primary passthrough tunnel goes down, traffic goes to Backup tunnel.

  • The IP SLA Rule would look like this, with the same tunnel specified for the Down and Up Actions.

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  • In the URL(s) field, the protocol identifier is required only when specifying HTTPS, as in https://www.google.com.

Example #3 – Monitor Interface (LAN0)

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  • On EdgeConnect - A, we want subnet advertising to be conditional on LAN0 being up.

  • Its IP SLA Rule would look like this, with the Default Subnet Action being to resume advertising subnets.

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Example #4 – Monitor Interface (WAN0) to Ensure High Availability

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  • If WAN0 goes down on the VRRP Master, we want to decrease its Priority so that traffic goes to the VRRP Backup.

  • Its IP SLA Rule would look like this, with the Default Subnet Action being to revert to the original Priority.

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    NOTE: In this instance, the WAN0 interface was given the label MPLS to match the service to which it connected.

Example #5 – Monitor VRRP

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  • To monitor the VRRP router state, use VRRP Monitor and specify the interface on which the VRRP instance is configured.

    In this example, it is LAN0.

  • Here we are looking at an instance where the VRRP role changes, but priority does not, for whatever reason.

  • Its IP SLA Rule would look like this, with the Default Subnet Action being to revert to the original Priority.

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    NOTE: In this instance, the WAN0 interface was given the label MPLS to match the service to which it connected.

  • Another option would be to specify Down Action = Modify Subnet Metric. The Web UI automatically produces another field in which you can add a positive value to the current subnet metric. Up Action = Default Subnet Action would return the subnet metric to its original value.

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IP SLA Tab

Use this dialog box to set rules to your IP SLA. Define the Monitor and Actions by completing the following steps.

Monitor

There are four options to choose from for a Monitor:

OptionDescription
InterfaceMonitors the operational status of a specific local interface.
PingMonitors the reachability of a specific IPv4 address.
HTTP/HTTPSMonitors the reachability of an HTTP/HTTPS endpoint.
VRRP MonitorMonitors the VRRP router state (TRUE if Master; FALSE if Backup) for a VRRP instance(s) on an interface.

Based on the Monitor chosen, the Web UI displays the appropriate fields and options.

Actions

There are eight available Down Actions:

Down ActionDescription
Remove Auto SubnetRemove from the subnet table an auto subnet for a port (including all VLAN and subinterface subnets).
Increase VRRP PriorityIncrease the configured VRRP router priority by a delta amount.
Decrease VRRP PriorityDecrease the configured VRRP router priority by a delta amount.
Enable TunnelEnable a passthrough (internet breakout) tunnel Up for IP Tracking (SLA) purposes.
Disable TunnelDisable a passthrough (internet breakout) tunnel Up for IP Tracking (SLA) purposes. The tunnel no longer can be used for load balancing purposes (when load balancing traffic between multiple passthrough tunnels), although it still can be used as a last resort for traffic forwarding.
Disable Subnet SharingDisable subnet sharing of subnets to other EdgeConnect peers on the appliance.
Modify Subnet MetricAdd a metric delta to the metric of all subnets shared with EdgeConnect peers.
Advertise SubnetsAdvertise subnets to EdgeConnect peers.

There are two default Up Actions:

Up ActionDescription
Default Subnet ActionThis reverts whatever was the Down Action back to the normal state. Examples:
  • If Down Action = Disable Subnet Sharing, the Up Action re-enables Subnet Sharing.
  • If Down Action = Remove Auto Subnets, the Up Action re-adds the auto subnet.
  • If Down Action = Modify Subnet Metric, the Up Action restores subnet metrics to their original values.
VRRP DefaultReverts the VRRP priority back to the configured value.

NOTE: If a default Up Action is used, it must match the Down Action.


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