The WAN (Wide Area Network) has become a critical success factor for many of today’s major IT initiatives. Storage and server consolidation; data replication and disaster recovery; web and server based computing; and voice and data convergence all demand LAN-like (Local Area Network) performance. To this end WAN optimisation and application acceleration technologies have become crucial in enabling the WAN. 

Brandon Rochat, sales director: Expand Networks Africa, explains that the characteristics of modern, progressive enterprises have led to significant IT challenges, “On the one hand an enterprise’s workforce has become more and more distributed while, on the other, its business critical applications and information have become more centralised.
"This has created an operational ‘chasm’ between employees at the enterprise edge and the business applications and information they need to do their jobs, which typically reside in the datacentre. To bridge this ‘chasm’ enterprises are demanding LAN-like performance, throughput and availabilty from their WAN.”
Rochat explains that today’s WAN infrastructures have, however, evolved over many years to become a very complex environment. Multi-vendor equipment, advanced network services, and bandwidth intensive applications have all conspired to make the WAN an environment where latency, congestion and bandwidth limitations can be commonplace. Advanced networking features and services rely on IP packet header information to be effective and, in WAN environments, full or partial packet transparency is essential for the successful integration of these features.
Deploying a WAN optimisation and application acceleration solution into an existing WAN environment can thus be hugely problematic. The challenge is not to break any of the existing functionality such as QoS, security or routing. However, by compressing traffic and altering packet headers these functions can be severely compromised.
“Many WAN optimisation products hide accelerated traffic in opaque tunnels that break these network services, compromising the reliable operation of voice, data, and security in the network,” says Rochat.
He adds that any vendor solutions that do alter packet headers have to implement a workaround in order to become transparent, hence adding further complexity and cost.
Lack of transparency causes a number of issues. “Whatever the IP addresses are on the client’s side, they need to appear again on the server so Intrusion Protection Systems (IPS) don't get confused by addresses that change – hence the need for transparency,” says Rochat.
A lack of transparency can also be a cause of WAN routing issues. He adds that in MPLS (Multi-Protocol Label Switching), a high level of transparency is required to take advantage of advanced services.
The solution then? Router Transparency Mode (RTM): a unique compression mode developed by Expand Networks that provides full IP header transparency for compressed traffic such as SAP, Lotus, Oracle, Exchange and Citrix.
“In RTM the full IP header is preserved and the network has full visibility of all IP flows,” says Rochat.
In addition, RTM seamlessly integrates into any WAN infrastructure without the need to reconfigure existing network devices.
What this means for a network? Using Expand Networks’ RTM, the edge routers can classify, shape and mark traffic and IP flows. The original provisioning on the routers can be maintained without modification or changes. In addition, the NetFlow probes can report data on the actual IP flows.
Rochat explains that RTM also enables encryption to be applied to sensitive traffic, “Threats can be identified and prevented, and unauthorised traffic can be blocked.”
And, since RTM maintains the original IP flows, it additionally enables the user to employ per-session-services on the network. For example, session-based load balancing and/or session-based QoS schemes. The combination of these capabilities results in a significant reduction in the number of engineering resources required to deploy, maintain and support this RTM solution.
While WAN optimisation and applications acceleration technologies are proving more and more critical to enabling the WAN, vendors like Expand Networks are demonstrating that all “solutions” are not the same. And, with Router Transparency Mode already making its mark in the industry, the Expand Networks solution looks set to shake up the standard approach to issues of transparency.