A Link Balancer is a network-based appliance designed to proactively manage bandwidth and multiple ISP or private links. Typically, these devices are installed between the firewall and modems and/or routers as shown in the following diagram to the right:
Link Balancers will perform the following functions:
- Link failover: should an ISP link not be available one or more links will handle the traffic until the troubled link returns to normal.
- Outbound traffic balancing: the link balancer will be able to distribute traffic leaving the organization across available links based on organizational preferences
- Inbound traffic balancing: through DNS (Domain Name Service) interception, a link balancer will be able to distribute incoming traffic across all selected links. Common examples include roaming VPN clients, webmail access, transactional applications and email retrieval by remote users.
- Session persistence management: with certain types of traffic, sessions such as SIP (VoIP), HTTPS (secure web site access) and FTP (File Transfer Protocol) cannot be balanced.