Standard Local Survivability (SLS) consists of a module built in to G430 Branch Gateway or G450 Branch Gateway to provide partial backup gateway controller functionality. The gateway provides the backup function when the connection with the primary controller is lost. To provide Communication Manager functionality when no link is available to an external controller, you can use a G430 Branch Gateway or G450 Branch Gateway without a local S8300E. Standard Local Survivability (SLS), Local Survivable Processor (LSP), and Branch Session Manager (BSM) are compatible with Edge Friendly Branch Survivability.