"Traffic on mobile networks is growing rapidly, with further exponential growth expected over the next five years, notes Aditya Kishore, Senior Analyst with Heavy Reading and author of the report. "A major driver of this growth is video traffic, which is expected to account for the majority of mobile traffic in 2012 itself. Operators are looking for ways to manage their costs in the face of this growth, without affecting end-user quality of experience (QoE)."
The location of caches depends on the issue the operator is trying to address, Kishore explains. "Today the majority of caches are to be found at international links, peering points, etc. - typically based in a fairly centralized data center and aimed at managing transit costs. But there is now a trend toward caching at the Gi interface (between the GGSN in a 3G network, and the Internet). This is aimed at reducing latency and improving end-user QoE."
Key findings of the report include the following:
Caching is most effective the closer it is to the consumer. This relieves the maximum amount of upstream bandwidth and offers the highest end-user QoE, since content has to traverse the shortest possible distance. Mobile operators are interested in pushing caches beyond the Gi interface and closer to end users, but crossing the Gi creates a long list of new challenges.
"Breaking the tunnel" is a challenge for edge caching on mobile networks. In mobile networks, data traffic is encapsulated in a series of GTP tunnels between the GGSN and the base station. If operators want to cache content anywhere on this stretch, they must "break" the tunnel and the security, select the content they wish to cache, and send the rest on. It appears that most operators - concerned about security implications and increasing complexity and cost - are not very keen to do so.
Vendors such as Stoke Networks and Ruckus are offering operators break-out solutions for offloading traffic at the edge. These vendors are able to navigate the requirements for breaking the tunnel. As such, caching vendors can partner with these solution providers or just get deployed in their slipstream without having to engineer a comprehensive break-out solution themselves.
Caches are likely to become more distributed over time, but it will probably be a few years before widespread deployment occurs at the edge. Today, we are more likely to see deployments at the Gi interface. The key drivers for pushing further out on the network will be the transition to LTE, and potentially the emergence of small cells and standardized break-out solutions for offload.
Crossing the Gi: Will Edge Caching Be the Key to Managing Mobile Traffic? costs $3,995 and is published in PDF format. The price includes an enterprise license covering all of the employees at the purchaser's company.
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