Enhanced Session Policies (ESP)™

Only the Edge platform combines this form of enhanced session control with advanced policy-routing. When deployed in a multilink environment, this technology can ensure that critical applications maintain the session persistence required in order to prevent disconnects which can happen when ISP links are load balanced.

Session Persistence is critical for maintaining connectivity when load balancing Internet traffic across multiple links. The problem is that most link load balancers do not incorporate the ability to properly monitor, manage, and control session persistence across various types of network applications and those which do, often require that ALL traffic be forced out a specific WAN link.

This translates either to non-optimized performance, or potential disconnects for mission critical traffic, either of which is a significant issue for maintaining productive end-user connectivity.

By design the EdgeXOS platform has built-in technology which ensures reliable bandwidth management across multiple WAN links, and thus our products ensure both optimized performance when utilizing multiple links AND complete session persistence for mission critical applications like VoIP, Citrix, CRM and ERP.

Intelligent Vector Mapping

Vector Maps are used to ensure session persistence so that traffic that comes in via a particular WAN link goes back out the same link. This is critical for most web-based e-commerce applications, including SSL based applications.

By creating Vector Maps, an IT administrator can ensure proper application balancing and failover for inbound services. This is a key component to providing a total network load balancing solution. Generally Vector Maps are required whenever PAT or One-to-One NAT mappings are used for inbound services.


Similar to application proxy solutions VirtualNAT enables inbound services to be proxied to internal servers and network devices. There are some limitations to VirtualNAT (it does not support some applications) and always shows inbound connections coming from the Edge appliance. However it's simple configuration makes it the favorable method for load balancing inbound traffic under most circumstances.

How Does It Work

Our ESP technology tracks sessions in real-time and will automatically ensure that each session maintains its "stickiness" to a specific WAN link once the session has been initiated. The administrator also has the ability to re-direct application traffic on a per application and/or per destination basis.

Further, the network administrator can also create policy routes whereby the ESP module will split sessions between links but only when those sessions can be split without causing disconnect problems. This capability is unique in the EdgeXOS platform and is one of the ways in which we ensure network optimization in multi-link deployments.

By monitoring each outbound session the EdgeXOS platform is able to optimize outbound connections by fully utilizing each WAN link to its fullest which maximizes ROI for the end-user.