Cloud computing is a major trend enabling more efficient, flexible and green IT for remote offices and mobile users. Citrix is the leading technology supporting this trend. However this shift of computing paradigm loads more data onto the associated WAN, which at the same time must become more responsive. Opteq has developed an intelligent solution to compliment Citrix deployments; with one Opteq unit in the data centre the network is fully optimised for all network traffic, the Citrix users consistently experience ‘LAN’ levels of performance at remote locations and costly WAN upgrades are avoided. Additional units can be deployed at large remote locations that both offload and thus enhance the Citrix servers and further accelerate applications.

Opteq has benefited greatly from these trends. Many corporate and governmental organisations have chosen Opteq to facilitate their move to cloud computing. Opteq’s unique range of network optimisation appliances using the latest industry standard processors are industry price-performance leaders. All Opteq devices come complete with fail-safe functionality and are offered in redundant configurations and/or with 24/7 support where necessary.

The Challenge

Using Citrix, remote users access multiple applications over the WAN, which often has limited bandwidth, latency, and congestion issues. These applications compete with other network traffic and any congestion can choke their vital communications channel – even networks running at 50-75% capacity often have short bursts that go well beyond that level leading to unpredictable response times as there is no spare capacity to absorb bursts. Furthermore Citrix is a highly interactive application, requiring rapid transfers for many small packets and many acknowledgements before the applications can proceed.

Each Citrix user on an enterprise network utilizes a significant amount of WAN bandwidth. As the number of Citrix sessions increase they battle each other for bandwidth until eventually the link is congested and packet losses start to occur. Any UDP packets also on the network (e.g. VOIP) are dropped and lost forever whilst TCP packets are retransmitted adding further to the congestion. Citrix’ ICA is highly efficient, minimizing the chattiness and total data exchanged. However transporting application traffic across the WAN where it previously traversed the LAN often results in poor user experiences.

More demanding applications such as graphical presentations, streaming media, print jobs and file transfers can swamp the link for all other users. Printer and similar traffic is often unmanaged causing problems on shared lines. Citrix allows the maximum bandwidth for a session to be set, which protects the bandwidth on the server side, but this means sub-optimal results. The effect of this is ever increasing response times and end-users becoming frustrated at inconsistent performance. Opteq provides the best of both worlds, limiting the session while the link is saturated, but fully using it when it is not.

Why Not Add More Bandwidth?

Adding more bandwidth does not necessarily improve the performance of an application over the WAN. A bandwidth upgrade, perhaps at significant and maybe unnecessary cost, would increase WAN capacity but still would not solve problems of latency and inconsistent demanding application performance. More bandwidth allows more ‘conversations’ to happen at the same time, but more bandwidth does not reduce the time it takes to send and receive a packet of data or a response. Opteq’s WAN optimisation technology addresses these problems arising from high latency or scarce bandwidth.

Opteq’s Wan Optimisation Technology

• Host Pacing ensures that higher priority traffic types such as Citrix essentially have a free lane on the network at all times by controlling traffic of all types at source without the need to ever queue packets thus completely eliminating congestion, packet retransmissions and drops.
• Queue Elimination provides the lowest latency traffic management solution available – Citrix packets are not slowed down by queuing technologies as used by competitors.
• True QoS makes certain that all critical business applications get the priority they deserve
• Fair Share enforces that an equal amount of bandwidth is provided to all network users and applications based on real time demand and Citrix ICA is not slowed or disconnected as a result of other traffic sharing the WAN link.
• Traffic Prioritization guarantees high performance even when WAN links become congested and allows successful redistribution of the bandwidth saved and gained via acceleration
• TCP Window Scaling manipulates window sizes to allow better utilization of links and increase throughput of data transfers over high bandwidth and/or high latency links.
• Application Pipelining improves application response times and reduces unnecessary overhead through smart round trip elimination and accelerated connection establishment.
• UDP Rate Control manages UDP packets at the application level providing much more intelligent management than aggregate queuing schemes allowing inbound and outbound granular UDP control.
• Extended MPLS allows dynamic remarking of MPLS packets to maximise class utilisation.
• Latency and Jitter Management smoothes Citrix performance by measuring and managing latency and jitter.
• Flow Optimization improves TCP transmission efficiency for high latency networks, eliminates retransmissions and helps TCP recover quickly after packet loss to achieve the highest utilization of lousy and congested links.
• Network Balancing to manage any number of branch offices from a central location, with no limit to the number of rules or groups providing for maximum granularity, visibility, reporting and control. Rules can be time based to dynamically adjust according to busy times like month end. Detailed reports are logged and stored for long term analysis. Alerts can be configured for latency on a per application or host basis allowing administrators to be proactive rather than reactive.
• Network Management and Reporting provides a ready means of troubleshooting and prioritising traffic of all types including VoIP/video etc as well as allowing intelligent decisions to be made as to which branch sites will benefit most from faster links or edge units rather than blindly deploying kit.

Summary

With a single Opteq appliance, organizations can effectively monitor, manage and optimize their entire network and so greatly improve user experience whilst also increasing the number of users.

By applying multiple acceleration technologies, such as carrier grade layer 7 bandwidth management (used by some of the world largest carriers), QOS, TCP acceleration, compression and caching, Opteq’s appliances successfully maximise the performance of Citrix rollouts.

VPN and Compression offloading - These functions are often performed by the Citrix server itself. By offloading compression and encryption to the Opteq wan optimisers one can often double the number of users that the Citrix server itself can handle.