• SonicOS 8 Rules and Policies
• Overview
  • Working with SonicOS
  • SonicOS Workflow
  • How to Use the SonicOS Administration Guides
  • Guide Conventions
• Access Rules
  • Setting Firewall Access Rules
    • About Connection Limiting
    • Using Bandwidth Management with Access Rules
      • Enabling Bandwidth Management on an Access Rule
    • Creating Access Rules
    • Configuring Access Rules for IPv6
      • About Stateful Packet Inspection Default Access Rules
    • Enabling and Disabling Access Rules
    • Editing Access Rules
    • Deleting Access Rules
    • Restoring Access Rules to Default Settings
    • Displaying Access Rules
      • By Zones
      • By Column
    • Displaying Access Rule Traffic Statistics
    • Configuring Access Rules for NAT64
    • Configuring Access Rules for a Zone
    • Access Rules for DNS Proxy
    • User Priority for Access Rules
  • Access Rule Configuration Examples
    • Enabling Ping
    • Blocking LAN Access for Specific Services
    • Allowing WAN Primary IP Access from the LAN Zone
• NAT Rules
  • About NAT in SonicOS
  • About NAT Load Balancing
    • Determining the NAT LB Method to Use
    • Caveats
    • How Load Balancing Algorithms are Applied
    • Sticky IP Algorithm Examples
      • Example One - Mapping to a Network
      • Example Two - Mapping to an IP Address Range
  • About NAT64
    • Use of Pref64::/n
  • About FQDN-based NAT
  • About Source MAC Address Override
  • Viewing NAT Policy Entries
    • Changing the Display
    • Filtering the Display
    • Displaying Information about Policies
  • Adding or Editing NAT or NAT64 Rule Policies
  • Deleting NAT Policies
  • Creating NAT Rule Policies: Examples
    • Creating a One-to-One NAT Policy for Inbound Traffic
    • Creating a One-to-One NAT Policy for Outbound Traffic
    • Inbound Port Address Translation via One-to-One NAT Policy
    • Inbound Port Address Translation via WAN IP Address
    • Creating a Many-to-One NAT Policy
    • Creating a Many-to-Many NAT Policy
    • Creating a One-to-Many NAT Load Balancing Policy
    • Creating a NAT Load Balancing Policy for Two Web Servers
    • Creating a WAN-to-WAN Access Rule for a NAT64 Policy
    • DNS Doctoring
• Routing
  • About Routing
    • About Metrics and Administrative Distance
      • About Metrics
      • About Administrative Distance
    • Route Advertisement
    • ECMP Routing
    • Policy-based Routing
    • Policy-based TOS Routing
    • PBR Metric-based Priority
    • Policy-based Routing and IPv6
    • OSPF and RIP Advanced Routing Services
      • About Routing Services
        • Protocol Type
        • Maximum Hops
        • Split-Horizon
        • Poison Reverse
        • Routing Table Updates
        • Subnet Sizes Supported
        • Autonomous System Topologies
      • OSPF Terms
    • Drop Tunnel Interface
    • App-based Routing
  • Rules and Policies > Routing Rules
    • Configuring Routing Rules
      • Adding Static Routes
      • Probe-Enabled Policy-based Routing Configuration
• DNS Rules
  • Creating DNS Filtering Profiles
  • Configuring DNS Filtering
    • Creating DNS Policy Rules
      • Editing DNS Policies
      • Deleting DNS Policies
    • Configuring Global DNS Filtering Settings
    • Configuring DNS Filtering Custom Domains
  • Viewing DNS Rules Information
    • Viewing DNS Rules Using the Dashboard
    • Viewing DNS Filtering Reports
• Content Filter Rules
  • About Content Filtering Rules (CFS)
    • About Content Filter Rules
    • About UUIDs for CFS Policies
    • About Content Filter Action Objects
    • How CFS Works
  • Configuring CFS Policies
    • About the Content Filter Rule Table
      • Searching the Content Filter Rule Table
    • Adding a Content Filter Rule
    • Editing a Content Filter Rule
    • Deleting Content Filter Rules
• App Rules
  • About App Rules
    • What are App Rules?
      • About App Rules Policies
      • About App Rules Capabilities
    • Benefits of App Rules
    • How Does Application Control Work?
    • About App Rules Policy Creation
    • Licensing App Rules and App Control
    • Terminology
  • Rules and Policies > App Rules
    • Configuring an App Rules Policy
  • Verifying App Rules Configuration
    • Useful Tools
      • Wireshark
      • Hex Editor
  • App Rules Use Cases
    • Creating a Regular Expression in a Match Object
    • Policy-based Application Rules
    • Logging Application Signature-based Policies
    • Compliance Enforcement
    • Server Protection
    • Hosted Email Environments
    • Email Control
    • Web Browser Control
    • HTTP Post Control
    • Forbidden File Type Control
    • ActiveX Control
    • FTP Control
      • Blocking Outbound Proprietary Files Over FTP
      • Blocking Outbound UTF-8 / UTF-16 Encoded Files
      • Blocking FTP Commands
    • Bandwidth Management
    • Bypass DPI
    • Custom Signature
    • Reverse Shell Exploit Prevention
      • Generating the Network Activity
      • Capturing and Exporting the Payload to a Text File Using Wireshark
      • Creating a Match Object
      • Defining the Policy
• Endpoint Rules
• SonicWall Support
  • About This Document

About NAT Load Balancing

Network Address Translation (NAT) and Load Balancing (LB) provide the ability to balance incoming traffic across multiple, similar network resources. Do not confuse this with the Failover & Load Balancing feature in SonicOS. While both features can be used in conjunction, Failover & Load Balancing is used to actively monitor WAN connections and act accordingly on failure/recovery of the WAN interface(s), and NAT LB is primarily used to balance incoming traffic.

Load Balancing distributes traffic among similar network resources so that no single server becomes overwhelmed, allowing for reliability and redundancy. If one server becomes unavailable, traffic is routed to available resources, providing maximum up-time.

This details how to configure the necessary NAT, load balancing, health checks, logging, and firewall rules to allow systems from the public Internet to access a virtual IP that maps to one or more internal systems, such as web servers, FTP servers, or SonicWall SMA appliances. This virtual can be independent of the firewall or it can be shared, assuming the firewall itself is not using the port(s) in question.

The load balancing capability in SonicOS, while fairly basic, satisfies the requirements for many network deployments. Network administrators with environments needing more granular load balancing, persistence and health-check mechanisms are advised to use a dedicated third-party load-balancing appliance.

• Determining the NAT LB Method to Use
• Caveats
• How Load Balancing Algorithms are Applied
• Sticky IP Algorithm Examples