EXPERT ADVICE

The WAN Traffic Controller Juggling Act

The Internet has become a critical component in today’s fast-moving business environment and continues to play a central role in delivering mission-critical business applications and vital communications to employees, partners and customers. The Internet holds the promise for organizations to streamline operations, improve operational efficiencies and lower costs. As a result, businesses have come to rely on networked applications delivered over the Internet for day-to-day operations and as a means for gaining competitive advantage.

Because of the many possibilities for improving business operations, IT personnel are placing increased attention on application service delivery and the increasing role that their organization’s WAN (wide area network) plays within the application delivery ecosystem. The WAN is a critical component of today’s business infrastructure. However, the WAN is independent of the business, being under the control of the telco and Internet service provider (ISP), which is an important issue that all businesses that rely on the Internet need to address.

The high value that WANs possess is a direct result of the consolidation of the data center, the centralization of user applications, increasing mobility of employees, the need for business continuity, and the addition of IP (Internet protocol)-enabled applications such as VoIP (voice over Internet protocol) and CRM (customer relationship management).

WAN Link Controllers Give Businesses Control Over the WAN

By routing traffic over multiple service provider links, WAN link controllers create a redundant WAN architecture that provides reliable network uptime while directly impacting the performance of applications over the Internet. This improvement is enhanced by capabilities such as link load balancing and failover and the ability to shape bandwidth for specific applications. Integrated firewall, VPN (virtual private network) and denial of service (DoS) security also help to ensure that the associated reliability and performance gains do not get thwarted by security attacks.

WAN scalability and cost reductions are realized by the ability to have complete freedom of choice for ISP/telco connectivity, allowing network designers and administrators to deploy a variety of cost-efficient bandwidth options such as T1, cable, wireless, DSL (digital subscriber line), etc. The simplicity of adding and removing WAN links and service providers and the efficient use of existing connectivity resources through link load-balancing and bandwidth management techniques makes WAN link controllers so valuable. Additionally, these products are far more cost-effective and simple to deploy than trying to use Border Gateway Protocol (BGP) for bi-directional link load balancing.

Multimedia and other bandwidth-hungry applications that performed well over a local area network (1 Gbps) with ample capacity are being challenged to provide the same level of WAN performance over a T1 link (1.45 Mbps) or DSL link (500 Kbps). This is especially true when the WAN is bottlenecked, and as more applications such as streaming video and VoIP get deployed over the same WAN link. SMEs (small to medium enterprises) need a way to optimize bandwidth in order to meet traffic requirements and improve traffic flows.

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Today, the majority of articles written about WAN optimization tend to focus on technologies such as caching, compression and protocol acceleration. However, even with all the compression, caching and protocol acceleration money can buy, if the WAN link that the applications are running over fails, the applications will not get delivered — period. In today’s dynamic business environment, IT personnel need to have a network infrastructure that is redundant, flexible, scalable and can apply appropriate levels of bandwidth to specific applications running over the WAN.

Boosting the speed of WAN application delivery by directing traffic through multiple network paths is surprisingly straightforward. Using an airport analogy, adding a second runway can significantly improve traffic flow from such causes as airplane breakdowns, congestion and poor weather conditions. Similarly, the effectiveness of the multiple-path approach for WAN connectivity depends greatly on the traffic directing devices (i.e. WAN link controllers) and their ability to efficiently and accurately detect network congestion, make routing decisions to circumvent bottlenecks and prioritize applications with bandwidth guarantees. This needs to be accomplished in a manner that is relevant to the specific types of traffic payload being routed. For example, with VoIP traffic, a high-latency network path should be avoided; or for large file transfers, a low-bandwidth path should be avoided.

QoS Prioritizes WAN Connection Bandwidth for Mission-Critical Applications

Many WAN link controllers include the ability to manage applications over the WAN using traffic shaping and quality of service rules, allowing administrators to define traffic and application limits and enable application queuing to prioritize different traffic types. This allows greater control of available bandwidth so that high-priority applications such as VoIP are allocated the bandwidth they require for optimal delivery over the WAN. Bandwidth usage can be managed based upon business policies that are associated with specific mission-critical applications in order to avoid bandwidth contention.

In the first example here, an Internet-based business has two ISP connections using BGP for high availability. Its primary applications are VoIP and email. The applications run smoothly when the primary ISP connection is available. However, when that connection fails, the second ISP connection handles all the traffic, and the VoIP application utilizes most l of the available bandwidth, depriving the email application of bandwidth. This causes a business disruption, as a significant amount of their business is conducted via email, which dramatically impacts productivity and business communication.

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In the second example below, the WAN link controller uses QoS to prioritize the VoIP and email applications when the ISP connection is restored. By dedicating bandwidth for each application, the WAN link controller ensures that the applications will have bandwidth allotted to them, enabling each to have the bandwidth they need for optimal service delivery.

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WAN Link Controllers Put You in Control

Using WAN link controllers, network administrators can incrementally and seamlessly add WAN links as their business grows and subsequent bandwidth needs increase.

By moving intelligent switching functionality to the edge of an enterprise network, WAN link controllers provide administrators with a new level of control. Administrators can dynamically direct traffic based on service provider availability, line capacity, performance and other policies.

WAN link controllers are deployed in-line between gateway routers and firewalls. To monitor WAN connectivity status, they perform transparent health and performance checks to evaluate the quality and reliability for each ISP link. Using this information, the WAN link controller intercepts traffic flowing in and out of the LAN and automatically switches users to the optimal WAN links.

Where traffic is sent is determined via advanced algorithms that take into account elements such as bandwidth utilization and other criteria, including what an organization pays for each ISP link. Administrators can set these policies to define how traffic should be directed to service provider links in order to best leverage its bandwidth investments. The WAN link controller prioritizes traffic to achieve optimal application delivery. For example, the IT department can make decisions whether to prevent (or limit) the download of YouTube content and other non-business related Internet browsing on the WAN network during business hours. Or they can set up higher bandwidth priorities for mission-critical applications such as VoIP. As applications such as VoIP continue to grow, the need to optimize and efficiently manage them over WAN networks becomes critical. To that end, the WAN link controller allows administrators to optimize VoIP transmission by routing VoIP application usage based on IP address, traffic type, user address, etc. For example, all the VoIP traffic can be allocated on a single line and have a second line allocated to aggregate the combined bandwidth in order to accommodate the traffic load.


Ron Thomas is president and CEO at Ecessa, a manufacturer of WAN optimization products.


1 Comment

  • So, is this the same type of thing that shaping products like packeteer and netequalizer do, or is there some difference? Either way, nice breakdown of the process and strategy.

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