Aggregating services
Network aggregation services from companies such as iPass and Fiberlink Communications represent an early move toward convergence. The wireless and wired network services they bundle and resell from carriers around the world are used with client devices that support connections to multiple networks.
The various services are accessible from a common client software interface provided by the aggregator, so users can access the best available network wherever they are. The aggregator maintains the multicarrier relationships and provides back-end security, billing and settlement services.
The mobile WAN component of these offerings isn't yet globally cohesive, however. "The wireless support of today's providers is not yet mature enough" to consider aggregators for worldwide mobile convergence, says Albert Hitchcock, CIO at Nortel Networks. The communications company supports 27,000 global users carrying mobile devices equipped with both Wi-Fi and cellular technology.
IPass and Fiberlink both support access to Wi-Fi hot spots around the world and resell Verizon Wireless' Evolution Data Optimized (EV-DO) services in the US. Outside the US, however, customers usually must buy mobile WAN services directly from individual providers. The aggregators' connection management client software will allow access to these networks, but managing the global mobile WAN carrier relationships is a key one-stop-shop benefit that isn't yet available internationally.
For seamless internetwork roaming once the desired network connections are in place, mobile client/server VPN software can be installed to let wandering users maintain sessions across network boundaries while retaining authentication credentials. Also, some hardware vendors, such as technology partners Motorola, Proxim Wireless and Avaya, are starting to offer premises equipment that handles Wi-Fi-to-cellular signal handoffs for voice calls. Carriers are also exploring services-based handoff alternatives.
Today, the mobile components needed for expanding coverage via roaming among multiple networks must be bought and deployed separately. Achieving smooth roaming among wireless networks with no break in a session requires IT to buy, install and manage multiple physical connections per device and deploy special client/server software to enable session persistence when roaming.
In addition, Wi-Fi-to-cellular handoff products and services leave IT departments speculating about the logistics of merging their networks with a carrier's in terms of service levels, troubleshooting and security.
"The subject of service-level agreements is fastidiously ignored by those who advocate mixed 802.11 and cellular solutions," says Doug Hill, an associate technical fellow and network chief architect at The Boeing Co. Carriers have approached Boeing about running a carrier-controlled mixed network where the carrier charges for voice-over-WLAN calls handed off to Boeing's internal Wi-Fi network at a lower rate than for the portion of a call moving over the cellular network.
But in a potential bridged Boeing-carrier infrastructure, neither party could monitor or troubleshoot across the public/private network boundary without sharing management information with the other. Not sharing the information with the carrier could degrade service quality, but doing so could introduce security concerns, Hill says.
This conundrum is one reason why Nortel, at least in the short term, will probably use premises-based equipment for such handoffs. The company is running trials in the US of Wi-Fi-to-cellular handoffs with carriers, testing the capability as both a premises-based and a carrier services function, Hitchcock says.
Another reason to house and manage the handoff equipment internally for now, Hitchcock says, is that "there's no single, global carrier that can serve our 70-country footprint".
Roger Entner, vice president of wireless telecom at researcher Ovum, said, "Your carrier can loan you another [modem] card if you [travel internationally]. Your other option is to rely on global Wi-Fi hot spots."
Roaming issues are why United Parcel Service now does business directly with the world's five largest network operators. UPS drivers use the company's self-developed, laptop-based Delivery Information Acquisition Device (DIAD) to frequently transmit delivery status information to the corporate mainframe.