Load Balancing

Introduction

Load Balancing is a method aiming to spread traffic across multiple links to get better link usage. This can be done one per-packet or per-connection basis.

Method	Per-connection	Per-packet
Firewall marking	Yes	Yes
ECMP	Yes	No
PCC	Yes	No
Nth	Yes	Yes
Bonding	No	Yes
OSPF	Yes	No
BGP	Yes	No

Methods

Failover

You have Dual Wan connection and you want to create a link failover? In case, link to WAN1 goes down and link to WAN2 becomes active, you simply have to configure routes: Two gateway failover

Firewall marking

This method uses firewall packet marking to select one from multiple gateways.

• Per-Traffic Load Balancing
• Load Balancing over Multiple Gateways
• Manual:Load balancing multiple same subnet links

ECMP (Equal Cost Multi-Path)

This method uses multiple gateway with same cost.

• ECMP load balancing with masquerade
• ECMP Failover Script
• Manual:IP/Route#Multipath (ECMP) routes

PCC (Per Connection Classifier)

• Manual:PCC

Nth

• NTH load balancing with masquerade
• NTH load balancing with masquerade (another approach)
• Manual:NTH in RouterOS 3.x

Bonding

Can combine multiple links to achieve: higher speed, failover, load balancing.

• Bonding Examples

More detailed information about "bonding" you can find here: Manual:Interface/Bonding

OSPF

Two or more links are setup with dynamic routing protocol OSPF with equal cost. Then equal multipath routing is used.

• Manual:Routing/OSPF
• Manual:Route Selection Algorithm in RouterOS#Load balancing and dynamic routing protocols

BGP

• Manual:BGP Load Balancing with two interfaces
• Manual:Simple BGP Multihoming#Load_sharing_setup

External links

• wikipedia:Load balancing (computing)