Site-to-Site Channel Bonding

ECESSA
White Paper
Site-to-Site Channel
BondingWhite Paper
Site-to-site channel bonding enables two or more sites equipped with specialized WAN optimization controllers to provide WAN link aggregation load balancing and failover capabilities which communicate over multiple networks using the combined throughput of multiple and diverse WAN links at multiple sites. This technology allows local and remote sites to send and receive large data files as if they were directly connected by a physical high-capacity link - at a fraction of the cost of supporting such a link.The WAN optimization controllers used for site-to-site channel bonding are located between the LAN network and WAN connections at each site. They include Ethernet ports that allow businesses to connect (or multihome) to two or more ISPs (up to 15 depending on the controller). Internet sessions generated on the LAN are then automatically load-balanced based on available resources and directed to WAN links with the available bandwidth required by the outgoing traffic. Bandwidth aggregation In this way, the combined throughput of all the WAN links is available for sending and receiving combines multiple WAN links Internet traffic between sites. Should one WAN link fail, the controller automatically senses the into what is effectively one failure and reroutes traffic to properly functioning WAN link(s). When the failed link is restored, it is large network connection. immediately placed back into service. The benefits of these WAN optimization controllers are two-fold. First, WAN link redundancy with automatic failover eliminates the potentially costly problem of Internet outages. Second, aggregating bandwidth from any type of ISP and WAN link, even the least costly, allows businesses to cost-effectively and incrementally increase bandwidth as business needs require. This saves many businesses the expense of migrating to dedicated point-to-point connections or costly high-capacity lines, and therefore, paying for unused bandwidth.
Site-to-site channel bondingFor site-to-site channel bonding, WAN optimization controllers with intelligent link load balancing are installed at both a local and remote site and manage traffic over the Internet between the two sites using the combined (or bonded) bandwidth of multiple ISP or WAN connections. Each site connected by such a bonded link is assigned a unique identifier that allows it to be differentiated from other sites. Each site is also configured with addressing information for both the local and remote end of the bonded link. This allows the WAN optimization controller at the local site to identify traffic that should be sent across the bonded link and direct it to the specified IP addresses on the WAN link(s) of the remote site. When the WAN optimization controller identifies such outgoing traffic, it is disassembled at the packet level into separate streams of data, then encapsulated for transmission through the bonded channels and sent over all available WAN links. Since each encapsulated packet contains addressing information for a specific remote location, data is easily reassembled at that location. A typical example of how site-to-site channel bonding works, starts with a business that sends data from a local site to a remote site. Each site uses a WAN optimization controller to load balance IP traffic over two 768 kbps WAN links. By using two relatively low costs links, the business avoids the necessity of upgrading to a more expensive T3 connection which would provide more capacity than the business needs, and avoids a single-point-of-failure. When the WAN optimization controller at the local site detects traffic to be sent to the remote site, it breaks the traffic down into two separate streams and sends the streams simultaneously over its two WAN ports to the two WAN ports of the WAN optimization controller at the remote (bonded) site. The WAN optimization controller at the bonded site then reassembles the two separate streams into the original data and delivers it to the LAN. With two streams of traffic simultaneously sent and received over two separate 768 kbps lines, throughput for the traffic is effectively doubled. In other words, the traffic is delivered to the remote LAN in roughly half the time needed if both sites had a single 768 WAN connection. If the WAN optimization controller at both sites were connected to additional low-cost ISP links, the time need... [download for more]