Load Distributor (LoDi)


Load Director (LoDi) is a product which distributes telephony load (calls) across multiple devices. In it's simplest form LoDi is a load balancer, sending calls to PBX's or other devices downstream based on their availabile capacity and capabilities. The result is optimal use of each downstream device's capacity and capabilities.

LoDi's call distribution algorithms range from simple round-robin and waterfall to sophisticated and user-defined algorithms. Alternatively, LoDi can dynamically determine the capacity of downstream devices and direct calls based each device's available capacity. LoDi includes agents for monitoring downstream PBX's (such as Digium's Asterisk), REST based interfaces for querying intelligent PBX's, and user defined rules for calculating device capacity in realtime (for legacy devices/PBX's).

LoDi's is also a technology gateway, bridging various technologies, protocols, codecs, and more. LoDi can accept calls from TDM trunks, SIP trunks, IAX trunks, H323 trunks, and more and deliver them to any other trunking technology. Similarly, LoDi can offload processing from downstream devices by performing codec conversion, SSL decoding, etc. LoDi can even rewrite headers and send calls to different routes/extensions/trunks/etc. downstream with modified headers. The administrator can also decide if LoDi should stay in the call stream.

LoDi is available as a turnkey hardware device, a virtual device (for AWS / VMware), or as a software package which can be added to a Linux server. LoDi's capacity is limited only by the platform on which it runs. LoDi can also be clustered to create a high-availability load distributor, including comprehensive failure sensing as well as replication and synchronization of configuration and operating data between LoDi servers. LoDi uses the HAAst™ engine to create a robust high availability load distribution service. LoDi can also use the SecAst™ engine to provide anti-fraud and anti-hacking capabilities at the load distribution point.

LoDi is an easy to use solution, with shell (command line), telnet, socket, and web interfaces, suitable for beginners and experts alike. LoDi is ideal for large multi-site call centers, or businesses with a cross-section of PBX / device technologies which must be integrated into a seemless fabric.

LoDi is available in Free and Commercial editions. The Free edition is suitable for companies wanting to test if the basic functionality & compatibility meets their needs. In addition, the Free edition is a functional and useful load balancer for small multi-site environments. The commercial edition is suitable for companies with large multi-site PBX's, and/or the need to integrate incompatible trunk technologies.

LoDi is available in both free and commercial editions. You can get LoDi, as well as more documentation, at www.telium.ca.

Pre-Defined Distribution Algorithms

LoDi can direct traffic to any number of downstream devices using a range of predefined algorithms. Predefined algorithms include round robin (send an arriving call to the next device in order), waterfall (sending all calls to the current device until it runs out of capacity, then overflow to the next device), count equalization (send calls to keep all devices with an equal call count), fractional capacity equalization (send calls to keep all devices with an equal call count / call capacity fraction), lowest count (send calls to the device with the lowest call count), lowest fraction capacity (send calls to the device with the lowest call count / call capacity fraction), and more.

User Defined Distribution Algorithms

LoDi can direct traffic to any number of downstream devices using user-defined algorithms. LoDi can determine call destinations based on simple or complex rules the administrator defines (even interacting with external services to calculate the optimal downstream target). LoDi can also coordinate distribtion with HTTP/HTTPS load balancers to ensure call and browser traffic are sent to associated destinations.

Intelligent Agents

LoDi can query downstream devices to determine their capacity and dynamically adjust the call destination accordingly. LoDi includes an intelligent agent which runs on the same platform as a Digium Asterisk based PBX. The agent keeps LoDi up to date on desination capacity(ies), CPU load, IO load, etc. to ensure each PBX operates at optimal capacity.

Header Rewrite

When sending calls to downstream devices using a VoIP protocol (eg: SIP), LoDi can manipulate the header to provide additional information or change the destination of any call. Rules allow LoDi to intelligently change extensions, insert SIP header data from other sources, etc.

Trunk Protocol Conversion

LoDi can serve as a trunk gateway, enabling businesses to integrate incompatible trunk technologies. LoDi can intelligently extract/insert header information (for VoIP protocols) to facilitate downstream processings, and ensure capture of critical information from the original trunk protocol. LoDi supports SIP, IAX2, H323, and PRI (T1/E1) trunking technologies.

Codec Conversion

LoDi can offload codec conversion (i.e. transcoding) from downstream devices by converting between a variety of codec's including: G.711 ulaw, G.711 alaw, G.722, G.726, G.729, GSM, iLBC, LPC10, and Speex. The administrator can control permitted codec's by inbound and outbound trunk, allowing LoDi to offload transcoding work from downstream devices.

Intelligent Fallback

LoDi can treat Asterisk peers as equals (with either peer continuing in an active role indefinitely) or as primary/backup (with the backup peer returning control to the primary peer when possible). LoDi intelligently transfers control from the backup peer to the primary peer only once the systems are stable and the cluster is reconnected, only during a specified time window, only when the systems are idle, etc. as specified by the administrator. This intelligent fallback feature allows administrators to move VoIP traffic back to a primary system when users are least affected.

High Availability / Clustering

LoDi servers can be clustered to create a high availability load distribution service. LoDi is fully compatible with the HAAst engine to create a robust cluter, capable of detecting a broad range of failures and rapidly transferring control to its peer. Using the HAAst engine Lodi peers exchange configuration information, operational data, and more. LoDi clusters can even be combined with PBX clusters to provide the ultimate high availability for mission critical telephony environments.

Event Handler System

One of advanced features of LoDi is the event handler system, which lets administrators hook any program/script into events generated by or detected by LoDi. For example, events related to up/downstream trunk loss, destination at capacity, etc. can trigger scripts which take remedial action, notify administrators, change routes, etc.

LCD Interface

End users and administrators will appreciate the ability to quickly view the status of the LoDi server (and cluster) from an LCD panel directly on the front of the PBX chassis. Administrators can optionally enable control of LoDi from the panel as well, allowing end-users to promote/demote/shutdown a LoDi cluster member with the push of a button on the front of the chassis.

Telnet Interface

Administrators will be immediately comfortable with the simple and powerful telnet interface to LoDi. The server can be managed and controlled from a telnet interface, whether from a PC, a tablet, or a cell phone. The interface includes online help, and user friendly rich terminal output.

Browser Interface

Seasoned administrators and novices alike will be comfortable with the simple and powerful browser (web) interface to LoDi. The server can be managed and controlled from any browser, including a PC, a tablet, or a cell phone. The interface includes simple control over the cluster, viewing of event logs, and more.

Socket & PHP & REST Interfaces

Developers will appreciate the socket, PHP, and REST (Representational State Transfer) interfaces to LoDi, as the power and control of LoDi can be easily expanded and integrated with other system administration and monitoring tools. LoDi includes sample code to demonstrate how to extract data and control LoDi via a web service, via a PHP class, and via the socket interface. LoDi monitoring can also be connected to commercial and free monitoring tools (eg: Nagios).


LoDi is available as a turnkey hardware device, as a virtual machine (for VMware), or as a package which can be installed on a Linux OS. LoDi is simple to install and integrate into any existing environment. New installations can be up and running within 2 hours; and repeat installations (for integrators) can be completed within 20 minutes.


The LoDi software is produced by Telium. Telium can be reached at www.telium.ca or info@telium.ca

Created by: ocgltd, Last modification: Sat 15 of Jul, 2017 (16:35 UTC)
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