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Elfiq Core Technologies |
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The Elfiq Link Balancer (or Link LB) provides redundant connectivity by balancing multiple Internet and private links from various providers. This technology is also known as a WAN load balancer.
Elfiq Link Balancers are built around our Elfiq Operating System (EOS) which has proven to be very powerful and robust. The hardware platform for our products has no mechanical parts, which reduces the risk of hardware failures. Our product's entire configuration resides in Flash memory on the device to enhance robustness and performance. Physical redundancy is available with rackmount models.
In summary, the Elfiq Link LB differentiates itself by operating at the data link network layer (layer 2) to manage synchronous or asynchronous telecommunication links. This prevents the use of complex protocols, such as BGP (Border Gateway Protocol) to support multiple links. It usually resides between the external routers and the firewall, or any other public or private link, and its installation is completely transparent to the rest of the network.
Link Balancer vs router
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A router will typically handle 2 links with different weights in a failover scenario for outgoing traffic. It verifies the availability ONLY of its next hop to deactivate a route and use the second one. It is a failover scenario.
An Elfiq Link Balancer permanently monitors its links to verify their availability by polling far into the Internet. Link LB keeps real time metrics like the response time trip (RTT) and bandwidth usage of each link. Those metrics are used for algorithm decision making and to verify logical routing errors on the ISP network (for example loops). The Link LB can support many links in parallel to their maximum usage for optimizing available bandwidth to users.
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A router can NOT select a route in real time based on the link states and metrics. A router will route packets without modifying the packet IP source, this means the packet could come back on the failed link. This is not viable for supporting INCOMING services on a multi-homed network. For the services accessed from the outside and for remote users (VPN, SMTP, WEB SERVER, terminal server, etc.), Elfiq Link Balancers add intelligence to the DNS service to handle DNS requests and give the selected link IP address for optimized performances and 100% availability. Routers are UNABLE of those functionnalities to insure availability of incoming services at all times.
Elfiq LB algorithms are very granular and can be applied on all combination of source IP/destination IP/protocol/port and link. This ensures optimal control of all traffic flows.
Installation
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The physical installation of the Elfiq Link Balancer is the simplest on the market. All you need to do is plug in two Ethernet cables and traffic will automatically start to flow through the unit. Afterwards, all that will be needed is to create balancing rules so you can tailor the load balancing to your needs.
The Elfiq Link Balancer is completely independent from the other systems, as well as Internet service providers. You do not need any special configuration in your telco routers. The Link LB does not use BGP (Border Gateway Protocol) and does not require an ASN (Autonomous System Numbers) either. Since it operates at the data link layer (layer 2) of the OSI model, no network or sub network changes are required. |
Primary Link (inline operation)
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When installing an Elfiq Link Balancer, an organization usually already has infrastructure in place and one telecommunication link. This first link is called the primary link. The firewall and all servers are configured with the IP addresses of the primary link. The strength of the Elfiq Link LB is that it keeps the primary link concept and manages to load balance traffic on all links transparently. This means the firewall and servers never know they are being balanced. No reconfiguration or IP address migration is required. The Link LB must be perceived as a "black box" that is transparent to the rest of your network and manages all links according to advanced algorithms.
Operating at the data link layer (layer 2), the Elfiq Link Balancer does not require any IP addresses, except for the dedicated management interface. It’s practically invisible to the rest of the network, which makes it a highly secure device. |
Virtual Forwarder Interface module(s)
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A Virtual Forwarder Interface (or VFI) can be defined as a network bridge (data link layer of the OSI model) which handles all tasks related to packet balancing by the Elfiq Link Balancer.
The basic role of the virtual forwarder interface is to forward traffic between two or more interfaces while providing a fast packet interception service. A VFI consists of a minimum of 2 physical network interfaces, with at least one of them acting as the inside interface, and the other(s) as the outside interface(s) to handle the different links.
The LB-2000 and higher models can load multiple instances of the VFI module (up to five). Refer to the product specifications for additionnal information. Each one has it's own ports and configuration and run as a virtual link balancer into the same device for custom balancing scenarios and global geographic balancing (Global Geolink). |
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Failover mode
Robust and flexible, Elfiq Link LB integrates a real time failover engine, allowing the addition of a second link balancer in a fault tolerant configuration. The Link Balancer's system and configuration reside in FLASH memory on the device, thus eliminating the use of any mechanical parts (e.g. hard disk) and therefore reducing the risk of failure.
Configuration
Besides being able to adapt to any type of link, the Elfiq Link Balancer uses advanced load balancing algorithms on different protocols to manage traffic on multihomed networks. Algorithms can be used both for incoming and outgoing traffic. Another strength of the Elfiq Link Balancer is its granularity. Algorithms for load balancing can be applied to entire protocols or specific to source IP/ports. Balancing rules can use different algorithms:
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Round Robin (RR)
Weight First Algorithm (WFA)
Least Traffic First Algorithm (LTFA)
Equalized Traffic First Algorithm (ETFA)
Weighted and Equalized Traffic First Algorithm (WFA-ETFA)
Ordered Preferred First Algorithm (OPFA)
Round Robin No-Gmac (RR-nogmac)
Best SitePath First Algorithm (BSFA) |
Inbound requests can be distributed to multiple servers. The Link LB supports persistent sessions (or persistence) under a variety of protocols. This is required for compatibility reasons. The most common protocols are FTP, IPsec and PPTP.
Traffic segmentation
Quality of Service with a single link requires the use of expensive devices with mitigated results. Multiple links preserves redundancy and give more options to the network administrator. For the most efficient Quality of Service, Elfiq recommends to do traffic segmentation.
The strength of the Elfiq Link Balancer is its granularity. Algorithms for load balancing can be applied to entire protocols or specific to source IP/ports. Traffic segmentation approach is to separate various traffic types on different links. This way, corporate services (like email, EDI, web hosting, VoIP) can be on the primary link during normal operation. Bandwidth intensive protocols are on the second or third link and will not saturate corporate services. In case of a link failure, IP services are merged on remaining links.
A similar approach is recommended for VPN remote users. With home high speed internet, a few teleworkers can easily saturate a corporate link. Traffic segmentation can be done for both incoming and outgoing traffic.
Another important feature for Quality of Service is rate limiting. This function allows to reserve or restrict the bandwidth for a greater management and control on IP traffic, priority, and link selection.
Management
All Elfiq Link Balancers have a dedicated management port. A Link LB can be managed through a secure SSH console access (CLI) or through a graphical management tool available on the Windows platform: The Elfiq Explorer.
Link balancer events and alerts are sent to a remote syslog server on your network through the management interface. A basic syslog server is also available on the graphical user interface management console, should you need one.
An SMTP alert service is available to send e-mails when an important event occurs.
All Link LB statistics are also available via SNMP from the management interface. Elfiq is registered with the Internet Assigned Numbers Authority, (IANA, www.iana.org) at the MIBS SNMP enterprise level. The OID number reserved for Elfiq is 19713.
An easy-to-use application programming interface (API) is also available (XML API) for the configuration and management of your Link LB. Because it uses standard XML commands, any language can be used, such as Perl, C, Visual Basic, etc.
Universal power supply
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All Elfiq Link Balancers have a universal power supply. Simply change the power cord to fit your country specific electric power frequency, voltage and plug adapter. |
Additionnal information
For additionnal information about the Elfiq Link balancer, please consult:
You can also consult the Download section for product documentation, utilities and webcasts (many languages) or contact us.
Download the Elfiq Technologies overview document
