--- title: "Internet overflow" canonical: "https://docs.aryaka.com/space/KNOW/1299775754/Internet%20overflow" format: markdown --- ANAPs deployed in edge routed mode (ERM) can support dual ISP links. One ANAP interface is specified as the primary ISP link and is used for internet traffic by default. The other ANAP interface is specified as the secondary ISP link. Internet Traffic Controller (ITC) controls which interface is used for your internet traffic by monitoring the interfaces' ICMP health to determine their current status (GOOD or BAD). If the interface for the primary ISP link is BAD, internet traffic is switched to the secondary ISP link. Internet Overflow is an additional feature that you can have Aryaka support enable if you want to use both ISP links for your internet traffic. If both interfaces have an ITC status of GOOD, Internet Overflow determines which ISP link to use based on link utilization. Each ISP link is configured with high and low capacity parameters (described in the following section) that are used to determine link utilization. Link utilization is continuously monitored and subsequent new internet traffic flows are directed towards the appropriate ISP link as required. Internet Overflow functionality When Internet Overflow is enabled on an ANAP, the following default parameters are used to determine the ISP links used for internet traffic: Primary High Limit—80% of the primary ISP link capacity. Primary Low Limit—70% of the primary ISP link capacity. Secondary High Limit—90% of the secondary ISP link capacity. Secondary Low Limit—80% of the secondary ISP link capacity. The primary and secondary limit percentages can be customized as per your organization's requirements. Contact Aryaka Support for details. Based on the default configuration, Internet Overflow processes internet traffic as follows: When both ISP links are connected, one must be configured as the primary connection and the other as the secondary connection. For each new internet traffic flow, the two ISP links are continuously monitored for link utilization. Under normal circumstances, internet traffic uses the primary interface until the Primary High Limit (80% of capacity) is reached. If the primary ISP link utilization exceeds the Primary High Limit, evaluate the secondary ISP link utilization: If the secondary link utilization is below the Secondary Low Limit - 80%, the internet traffic flow is switched to the secondary ISP link. If the secondary link utilization is not below the Secondary Low Limit (80% of capacity), continue using the primary ISP link for internet traffic flows.  If the secondary ISP link is currently being used for the internet flows, evaluate the following: If the primary link utilization is below the Primary Low Limit (70% of capacity), switch all new internet traffic flows to the primary link. If the secondary link utilization is below Secondary High Limit (90% of capacity), and the primary link utilization is above Primary Low Limit (70% of capacity), the internet traffic flow remains on the secondary link. If the secondary link utilization is above Secondary High Limit (90% of capacity), and the primary link utilization is above the Primary Low Limit (70% of capacity), the new internet traffic flow switches to the primary link.  Any time the utilization on the primary or secondary link is between the respective High Limit and Low Limit percentages, both links are considered overloaded and the preference is given to the primary link for the internet traffic flow. ITC performs checks on both the primary and secondary connections and compares the performance to the respective Low Limit percentage and routes the new internet traffic flow as appropriate. Monitor ISP link utilization ISP link utilization can be visualized in MyAryaka for both ISP links, as described in the following procedure: To view a site's ISP link utilization Log in to MyAryaka . The Home page appears. Click  SD-WAN   > Monitor in the left navigation pane. The Site: < siteName > page appears. Click the Reference Site drop-down list and select the site whose ISP link utilization you want to monitor. Click the Direct Internet bubble in the WAN Traffic by Network graph. The Network: Direct Internet page appears. Click the Time drop-down list and select the time period you want to view data for, then click Apply . The graphs update to display data for the selected time period. The Network Traffic by Provider graph displays the amount of traffic for each ISP link during the selected time period. Monitor ISP link health ISP link health, as determined by ITC, can be visualized in MyAryaka for both ISP links, as described in the following procedure: To view a site's ISP link health Log in to MyAryaka . The Home page appears. Click SD-WAN > Monitor in the left navigation pane. The Site: < siteName > page appears. Click the Reference Site drop-down list and select the site whose ISP link health you want to monitor. Click the Direct Internet bubble in the WAN Traffic by Network graph. The Network: Direct Internet page appears. Click the Health icon in the navigation bar located at the bottom of the page. The Health page appears and displays the following graphs for the selected site: ITC Latency ITC Loss Click the Time drop-down list and select the time period you want to view data for, then click Apply . The graphs update to display data for the selected time period. View preferred ISP link  Internet Overflow functionality is a subset of the Internet Traffic Controller service. You can verify that Internet Traffic Controller is enabled and view your preferred ISP link on a site's status details page. To view a site's status details page Log in to MyAryaka. The Home page appears. Click SD-WAN >  Status in the left navigation pane. The SD-WAN Status page appears. Click the entity you want to view details for in the Network Discovery diagram or table. The page appears and displays the following tabs if relevant to the selected site: Summary POP Tunnels Site Pairs Edge Links Routing ANAP Network Virtual Machine Security DCHP and DNS Click ANAP . The ANAP tab page appears: Click the Plus sign + icon for Internet Traffic Controller (ITC). Additional details are displayed. The interface with (Preferred) next to its status indicates the ISP link that is currently being used for your internet traffic.          In this topic Related topics Dual ISP support View a site’s status ANAP configuration - Edge Routed Mode