Key Concepts And Product Features - Fortinet FortiWAN Administration Manual

Introduction

Key Concepts and Product Features

WAN load balancing (WLB)
General speaking, load balancing are mechanisms (methods) for managing (distributing) workload across available
resources, such as servers, computers, network links, CPU or disk storage. The FortiWAN's WAN load balancing aims
to distribute (route) WAN traffic across multiple network links. The major purposes are optimizing bandwidth usage,
maximizing transmission throughput and avoiding overload of any single network link. When we talk about WAN load
balancing, it always implies automatic traffic distribution across multiple network links. Different from general routing,
WAN load balancing involves algorithms, calculations and monitoring to dynamically determine the availability of
network links for network traffic distribution.
Installation
FortiWAN is an edge device that typically connects an internal local area network (LAN) with an external wide area
network (WAN) or the Internet. The physical network ports on FortiWAN are divided into WAN ports, LAN ports and
DMZ (Demilitarized Zone) ports, which are used to connect to the WAN or the Internet, subnets in LAN, and subnets in
DMZ respectively. Please refer to FortiWAN QuickStart Guides for the ports mapping for various models.
Bidirectional load balancing
Network date transmission passing through FortiWAN is bidirectional that are inbound and outbound. Network data
transmission contains session establish and packet transmission. An inbound session refers to the session which is
established from elsewhere (external) to the FortiWAN (internal), while an outbound session refers to the session
which is established from the FortiWAN (internal) to elsewhere (external). For example, a request from the internal
network to a HTTP server on the Internet means the first asking packet is outgoing to the external server, which is an
outbound session established. Inversely, a request from the external area to a HTTP server behind FortiWAN means
the first asking packet is incoming to the internal server, which is an inbound session established. No matter which
direction a session is established in, packets transmission might be bidirectional (depends on the transmission
protocol employed). FortiWAN is capable of balancing not only outbound but also inbound sessions and packets
across multiple network links.
Auto Routing (Outbound Load Balancing)
FortiWAN distributes traffic across as many as 50 WAN links, under control of load balancing algorithms. FortiWAN's 7
advanced load balancing algorithms let you easily fine-tune how traffic is distributed across the available links. Each
deployment can be fully customized with the most flexible assignment of application traffic in the industry.
Multihoming (Inbound Load Balancing)
Many enterprises host servers for email, and other public access services. FortiWAN load balances incoming requests
and responses across multiple WAN Links to improve user response and network reliability. Load balancing algorithms
assure the enterprise that priority services are maintained and given appropriate upstream bandwidth.
Fall-back or Fail-over
FortiWAN detects local access link failures and end-to-end failures in the network and can either fall-back to remaining
WAN links or fail-over to redundant WAN links, if needed. Fall-back and Fail-over behavior is under complete control of
the administrator, with flexible rule definitions to meet any situation likely to occur. Links and routes are automatically
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Key Concepts and Product Features
FortiWAN Handbook
Fortinet Technologies Inc.