---
title: "Ring2All SBC - Dispatcher & Load Balancing Module Documentation"
description: "Documentation for Dispatcher & Load Balancing"
---

## Table of Contents
1. [Module Overview (Technical)](#1-module-overview-technical)
2. [Module Overview (Commercial/Business)](#2-module-overview-commercialbusiness)
3. [Module Overview (End User/Administrator)](#3-module-overview-end-useradministrator)
4. [Configuration Sections](#4-configuration-sections)
5. [Settings Reference](#5-settings-reference)
6. [Common Scenarios & Examples](#6-common-scenarios--examples)
7. [Limitations & Important Notes](#7-limitations--important-notes)
8. [Troubleshooting Tips](#8-troubleshooting-tips)
9. [Glossary](#9-glossary)

---

## 1. Module Overview (Technical)

### What Is the Dispatcher Module?

The **Dispatcher Module** in Ring2All SBC manages high-availability Session Border Controller traffic distribution, round-robin load balancing, weight-based routing, and automated failover monitoring across groups of Telephony Server media nodes, PSTN gateways, and carrier SBCs.

Powered by Kamailio's `dispatcher` module, Ring2All SBC sends active SIP `OPTIONS` keepalive pings at regular intervals to verify gateway health. If a node fails to respond or returns server errors (e.g. 500, 503), the Dispatcher instantly marks it as inactive (`IP_INACTIVE`) and re-routes pending traffic to healthy nodes.

### Architecture

```
┌─────────────────────────────────────────────────────────────────┐
│           Ring2All SBC - Dispatcher Architecture                 │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│  Inbound SIP Traffic ──> Kamailio SBC Core (Dispatcher)         │
│                                │                                │
│                     ┌──────────┼──────────┐                     │
│                     │ (Options Keepalive) │                     │
│                     ▼          ▼          ▼                     │
│                ┌────────┐ ┌────────┐ ┌────────┐                 │
│                │ Node 1 │ │ Node 2 │ │ Node 3 │                 │
│                │ (Active) │ (Active) │ (Failed)                 │
│                └────────┘ └────────┘ └────────┘                 │
│                     │          │          X (Skipped)           │
│                     └──────────┴──────────┘                     │
│                                │                                │
│                                ▼                                │
│                     Telephony Server / Carrier Pool                   │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘
```

---

## 2. Module Overview (Commercial/Business)

### Business Benefits

1. **Zero-Downtime Telephony Operations**: Automatically detects gateway failures in under 2 seconds, preventing dropped calls and agent downtime.
2. **Optimal Capacity Utilization**: Distributes traffic evenly across media servers according to processing capacity (weight algorithms).
3. **Carrier Cost Optimization**: Route traffic dynamically based on dispatcher group rules and carrier priorities.

---

## 3. Module Overview (End User/Administrator)

### What Can You Do in This Module?

- **Define Dispatcher Groups**: Create logical pools for Telephony nodes, PSTN Trunks, or Outbound Carriers.
- **Configure Load Balancing Algorithms**: Choose between Hash-based (Call-ID, From-URI), Round-Robin, or Weight-based distribution.
- **Set Probing Parameters**: Define SIP `OPTIONS` ping intervals, timeout limits, and failure thresholds.
- **View Gateway Health Status**: Real-time status monitoring (Active, Inactive, Probing, Disabled).

---

## 4. Configuration Sections

### 1. Dispatcher Rules Grid
Lists all registered gateways with group IDs, destination URIs, weights, priority, and real-time status.

### 2. Gateway Properties Form
Allows adding or editing destination URIs (`sip:192.168.10.32:5060`), flags, socket bindings, and description.

---

## 5. Settings Reference

| Field Name | Type | Options / Format | Description |
| :--- | :--- | :--- | :--- |
| `setid` | Integer | Positive integer (e.g. `10`) | Dispatcher Group ID. |
| `destination` | Input | `sip:host:port` | SIP URI of target gateway or media server. |
| `flags` | Integer | Bitmask (e.g. `8` = Probing) | Operational flags for Kamailio dispatcher. |
| `priority` | Integer | 0-100 | Routing priority order within dispatcher set. |

---

## 6. Common Scenarios & Examples

### Scenario: Configuring High-Availability Telephony Cluster

1. Create Dispatcher Set `1` for Telephony Server Media Pool.
2. Add Node A: `sip:192.168.10.30:5060`, Priority `10`, Flags `8`.
3. Add Node B: `sip:192.168.10.31:5060`, Priority `10`, Flags `8`.
4. Kamailio pings both nodes every 5 seconds. If Node A goes down, all traffic seamlessly flows to Node B.

---

## 7. Limitations & Important Notes

- Ensure `ds_ping_interval` is set between 2s and 10s to avoid unnecessary network overhead while maintaining rapid failover.

---

## 8. Troubleshooting Tips

| Symptom | Probable Cause | Solution |
| :--- | :--- | :--- |
| Node marked `INACTIVE` | Firewall blocking SIP `OPTIONS` | Verify port 5060 UDP is allowed between Kamailio and media nodes. |
| Dispatcher rules not reloading | Memory cache not synced | Run `kamcmd dispatcher.reload` via SBC CLI or API. |

---

## 9. Glossary

- **Dispatcher Set**: Logical grouping of destinations sharing the same routing policy.
- **Probing**: Periodic transmission of SIP `OPTIONS` pings to verify destination health.