SteelHead™ Deployment Guide : Path Selection : Overview of Path Selection
  
Overview of Path Selection
Path selection is a RiOS technology commonly known as intelligent dynamic WAN selection. You can use path selection to define a specific WAN gateway for certain traffic flows, overriding the original destined WAN gateway.
WAN egress control is a transparent operation to the client, server, and any networking devices such as routers or switches. When you configure path selection, the SteelHead can alter the next hop gateway transparently for the client traffic. This granular path manipulation enables you to better use and more accurately control traffic flow across multiple WAN circuits.
You must know the following nomenclature prior to reading the information in this chapter:
  • Topology - The topology combines a set of parameters that enables a SteelHead to build its view onto the network. The topology consists of network and site definitions, including information about how a site connects to a network. With the concept of a topology, a SteelHead automatically builds paths to remote sites.
    • For more information about topology IP segment parameters, see Topology.
  • Uplinks - An uplink is a logical medium that connects the site to a WAN network. A site can have a single or multiple uplinks to the same network and can connect to multiple networks. You can use multiple uplinks to the same network for redundancy. Uplinks serve as a logical connection that path selection uses to steer traffic. Local site uplinks are of upmost relevance for path selection.
    • For more information on uplinks, see Defining a Site.
  • Destination site - A destination site provides the IP segment parameter for a path selection rule destined towards a preconfigured remote site destination. The Any parameter selection is a blend of all configured custom sites, and the DefaultSite selection indicates any destination excluding preconfigured custom sites.
    • For details, see Configuring the Local Site and Configuring the Default Site.
  • Applications - An application is a set of criteria to classify traffic. The definition of an application enables the SteelHead to ensure that the traffic belonging to this application is treated according how you have configured it. Technically this means that the SteelHead can allocate the necessary bandwidth and priority for an application to ensure its optimal transport through the network. You can define an application on manually configured criteria or by using the AFE, which can recognize more than 1200 applications.
    • For more information about applications and the AFE, see Application Definitions.
  • Relay - Relay is traffic specified by the rule to be subject to path selection internal switching and follows the normal client default gateway (the original path) as intended by the end client or routed LAN.