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SwitchKit Redundancy

Overview

In the basic SwitchKit architecture, all call processing and OAM functions are performed through the LLC. All applications require the LLC for communicating with the switch. If the LLC stops running, no further call processing can take place. To eliminate the LLC as a single point of failure, run a redundant LLC.

Description

The Redundant LLC (RLLC) is a hot standby for the Primary LLC (PLLC). The RLLC mirrors the state of the PLLC, and, if the PLLC goes down, RLLC becomes the primary LLC. All applications connect to the RLLC automatically.

Running LLC in Redundant Mode

To run the LLC in redundant mode, use the -r argument. The -r flag tells the RLLC where to find the PLLC. This can consist of just a host name, or optionally a host name followed by a colon followed by a TCP port where the primary LLC is waiting for connections. By default, it assumes the default port of 1312. See Running Redundant LLCs.

You cannot run two LLCs on the same host computer accepting socket connections on the same port.

Running SwitchManager in Redundant Mode

For redundancy, SwitchManager uses the LLC and Application Redundancy. See Redundancy (10-1) in the SwitchKit Programmer’s Guide. When multiple SwitchManagers connect to LLC, the first one connected becomes Primary. This SwitchManager remains primary unless there is an LLC switchover. In this case, the new active LLC selects the first SwitchManager that connects as primary. In some cases, this induces a switchover of SwitchManagers, which is transparent to the system.

Specifying the location of the RLLC for Applications

Once you are running an RLLC, all applications that connect to the PLLC, including SwitchManager, must know the location of the RLLC so they can automatically reconnect to the RLLC in case of a PLLC failure. This is done through the following environment variables:

• SK_RLLC_HOST

• SK_RLLC_PORT

These values must be set before the applications are run. They are only examined upon start-up. You cannot dynamically configure SwitchKit Redundancy. Please refer to Environment Variables Modify SwitchKit Default Behavior

Example

For example, in the default file, you could have:

rllc_host: pc2

rllc_port:1200

This would specify to all applications starting up that there is a redundant LLC running on host pc2, on the TCP port of 1200. Environmental variables must be set the same on both the Primary host and the Redundant host.