Vector Routing Algorithm

Only the XOS platform incorporates this sophisticated algorithm for determining next session routing while maintaining persistence for each new network connection.

Routing Methods

The Vector Routing algorithm is designed to provide two fundamental services, dynamic network load balancing across multiple paths and reliability assurance in the event that one or more of those paths should fail.

Vector Routing uses various metrics (below) to determine how new network sessions should be routed over the various active links. Unlike other load balancing solutions, it does not use simple Robin-Robin balancing. Instead the algorithm is continuously fed metric information which it uses to determine the best next hop for outbound connections.

• Link Utilization
• Network Latency
• Link Packet Loss
• Calculated Jitter
• Administrative Weights

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.

VirtualNAT

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

Vector Routing routes traffic between the LAN and multi-WAN environment. This is accomplished by continuously evaluating the metric information obtain from the WAN links, as well as the multi-level outage detection system.

This same process is used for inbound connectivity (multi-WAN to LAN) as well. There are some significant differences however when inbound sessions are being balanced, particularly when applications like VPN and VoIP are concerned. For these applications, standard proxy services do not work well, if at all, and thus One-to-One NAT is generally recommended.

In these cases, a Vector Map is also required in order to ensure INBOUND session persistence, as seen in the diagram below.

Inbound sessions must be matched to their outgoing interface. Most firewalls and core Internet routers will drop sessions which appear to come from multiple sources.