Improving branch office connectivity

As more enterprises move their applications off of localised servers at local offices and on to centralised, hosted servers residing at company headquarters and data centres, IT departments have to adjust their tactics. They no longer have to maintain a large number of distributed servers; instead they need to ensure that the fewer, centralised servers and all the supporting infrastructures live up to expectations. Doing so requires highly dependable connectivity among all of an organisation’s branch offices and mobile users so business never suffers.

Fortunately, new technologies are hitting the market aimed at improving network reliability, latency and quality. Through the use of WAN acceleration tools and Broadband Bonding, a technique that melds various numbers of Internet lines into a single connection, organisations can centralize their applications and still provide fast and reliable application and data access to all their branch offices and mobile users

New Model, New Challenges
In a typical, localised model, there are often servers in every branch office—a very expensive and difficult operation to set and manage. The high penetration rates of broadband are changing all that. For countries in the European Union (EU), broadband accessibility has reached 100 percent, according to a report from the European Commission (EC). Specifically, 96.1 percent of users have access to fixed lines (ADSL, VDSL, cable, fibre, copper); by adding mobile coverage (2G, 3G, 4G, LTE) and satellite coverage, users have complete broadband accessibility, the report states.

As broadband networking lines became faster, more reliable and more readily available, enterprises began leveraging these lines to connect their branch offices with headquarters, enabling them to do away with all the distributed servers and instead run centralised servers at their corporate headquarters or in data centres. By definition, the users of the service (i.e., employees at the branch offices) and the provider of the service (i.e., the server in the data centre) are no longer collocated. In some cases, especially for multi-national organizations, the distances between the users and the providers are thousands of kilometers apart.

If a main server becomes inaccessible because a link goes down, there can be serious consequences. Branch offices will be shut out of the business until the link is re-established. As an example, growing number of organisations are moving towards IP-PBX based systems to provide phone services to their branch offices, so in effect, the branch office telephone system can go down, if their connectivity is having problems. Bottlenecks can also occur, slowing connectivity drastically.
IT departments also have less control of the situation, since broadband network uptime is under the control of the Internet Service Providers (ISPs) who own and operate the network. Nonetheless, for many, the cost savings of hosted architectures have been so convincing that IT departments are shifting towards them, in spite of the connectivity risks.

There are Service Level Agreements (SLAs) that ISPs provide for their clients. Clients can pay for expensive SLAs that guarantee uptime, but in most cases the penalty for not providing the promised Internet connectivity is limited to the pro rata fee that is associated with that outage. Unfortunately, that compensation may not match the losses incurred from an outage.

In addition to reliability challenges, the WAN link can become a bottleneck between the branch and headquarters or data centre. In most cases, the uplink speed of a branch office is much lower than the WAN connectivity speed of a headquarter office and this will throttle down the connectivity speed between those two nodes to the slower of the two links. In some cases, higher bandwidth options for the branch office can be very costly or even unavailable. The problem is more acute for multi-national enterprises because of the disparities among WAN options in various geographies.

Tackling the Challenges with Emerging Technologies
There are emerging technologies designed to address network reliability, latency and quality, including WAN Acceleration and Broadband Bonding.

WAN Acceleration – Unlike the name suggests, doesn’t touch the WAN transport, but attempts to modify the bits flowing through the WAN pipe. The idea is to minimise the number of bits that the application transmits to enhance the end-user experience. Some vendors in the space have added various protocol optimizations to add to the end-user experience (such as tuning TCP parameters ,etc.), which are primarily fixing the shortcomings of the ancient TCP protocol for the very specialized requirements of new applications that have become popular in recent years.

How can the amount of bits transmitted over a WAN connection be reduced without breaking any of the required semantics? The answer is, through caching and compression. If an application needs to transmit large files that are essentially replicas of each other with some minor differences, the logical method to add efficiency to that system is to simply cache the original file at the receiver side and then only transmit the delta of the new file, i.e., just the components that changed. The other technique is to compress the data prior to transmitting and decompressing it at the receiving end. Both approaches (sometimes used in conjunction) can provide advantages, if the application fits a certain profile. For example, for caching, the application should be one that essentially transmits very similar files over and over again (a good example would be a design firm sharing large design files between offices throughout the project as the design files are modified over time, albeit with minor changes). For compression, the requirement would be that the traffic is non-compressed and is non-encrypted.

Broadband Bonding – More recently, a new technology has emerged called Broadband Bonding. This is a sophisticated method that merges several WAN links into a fatter and more reliable IP pipe. Broadband Bonding is the latest link in the evolution of bandwidth aggregation that began from scenarios where the failover to the secondary Internet connection in case the primary line failed was done manually. Load balancing technology soon followed, which is an aggregation that is done at session granularity, i.e., each session is assigned to one of the WAN links. Finally, the most modern of all, namely Broadband Bonding, takes load balancing to a whole new level where the granularity in aggregation can be dropped to packet level. Broadband Bonding routers sit on top of WAN links and manage the WAN links by aggregation and advanced QoS (Quality of Service) so that a single and high-performance IP pipe is presented to the local area network at the office. Depending on the application, the Broadband Bonding algorithms would adapt and optimise the aggregated IP pipe for certain goals, such as maximized throughput, minimal latency, maximum reliability or anything in between.

Broadband Bonding bonds the various numbers of Internet lines into a single connection, providing faster connectivity via the sum of all the line speeds, ensuring that even global firms that have hundreds of branch offices scattered around the world can offer all their offices the same level of connectivity as the headquarters—all without the outlay of too much capital. The end result is a faster connection with multiple built-in redundancies that can automatically switch on a secondary line in case of a primary link fails.

Acceleration and Bonding Working Together
So which approach is better for enhancing branch office WAN performance - WAN optimization or Broadband Bonding? Should you try to minimise the amount of bits that are transmitted through the pipe, or should you try to make the pipe bigger? The answer is both. The fortunate reality is that these two technologies can work in conjunction and have very little overlap. For more specialised cases, the WAN optimization can provide very high performance gains; on the other hand, for certain applications it may have limited or no effect. On the other-hand WAN optimization provides no value for reliability. Broadband Bonding, however, will always enhance the WAN performance and provide the best performance out of the combined IP pipes and is clearly the most cost-effective way to bring the WAN reliability to high 9s, so a natural conclusion is to leverage both technologies simultaneously.