Standards Watch :GRX: Enabling IP Connectivity

The rollout of GPRS marks a lift from circuit-switched to IP services and 3G mobile services. The move to packet-switched connections will provide higher data speeds and permanent connections, enabling mobile users ubiquitous and higher-speed Internet access worldwide. This increasingly is demanded as roamers seek access to business applications, the Internet and intranets, from anywhere, anytime.

One of the biggest challenges, however, to high-speed data connections in GPRS has been IP interconnectivity for international mobile and international roaming sessions.

Roaming based on point-to-point links becomes unwieldy when it involves a myriad of roaming partners and multiple-vendor environments. Operators often have to go to fixed roaming through local ISPs, or partnerships with local providers. That makes guaranteeing SLAs difficult in IP, especially with multiple ISPs involved in agreements with other remote ISPs. For that reason, the GSM Association (GSMA) recommends the GPRS roaming network-at the core of which is the GPRS Roaming Exchange (GRX).


GRX nodes will act as the global IP backbone, which interconnects GPRS network operators and provides their subscribers with mobile access to applications when roaming outside their networks.

The standard is designed in full accordance with the IR.34 specification of the GSM Association, which recommends that GRX service providers meet the minimum requirements of a router, links connecting to GPRS networks, and links connecting to other GRX nodes.

Once those components are in place, implementation is expedited, as GRX service providers act as hubs, thus eliminating the need for GPRS operators to establish dedicated connections to each roaming partner.

"The ultimate goal is to have GRX carriers interconnecting with each other in order to provide one-stop shopping and traffic transport," says John Hoffman, who leads the GPRS initiative within the GSMA. He notes the GSMA has for many months been evaluating international IP carriers that wish to provide GRX services.

GSM operators are currently upgrading their GSM networks to support GPRS. Design and implementation of the GRX has been completed, and a small group of operators will be testing end-to-end roaming through the GRX throughout February 2001.

Sue Campion, manager of mobile carrier services for Cable and Wireless Communications in the United Kingdom, notes that "GRX is an area to watch closely, for it will enable such things as access to home networks when roaming." CW offers a range of services, including voice traffic, provisioning of data networks internationally and mobile Internet applications through a partnership with Nokia. Users have access to e-mail on their corporate servers and can work on files from their mobile phones. CW's development team is working on a GPRS roaming network that it expects will enable mobile operators to connect and exchange traffic with any mobile operator.

One of the more recent announcements for GRX involves a partnership between Infonet, which provides an established global IP backbone, and Comfone, which provides a roaming platform. Comfone expects to offer SLAs with very high built-in security and quality, facilitating QoS in roaming applications (See sidebar "What GRX Can Do).

The architecture used to build Comfone's GRX will run on Infonet's global network. The two companies will hold industry seminars in Europe and Asia-Pacific during the next two months to highlight GRX developments to GSM operators.

In the meantime, a GRX/Operator Task Force is working on QoS issues, "since SLAs between operators and GRX carriers will eventually have to raise QoS to a level above 'best-effort,' " adds Hoffman.

How operators charge for roaming will ultimately depend on the ensuing definitions of QoS. Once QoS has been brought into the market, operators will be able to bill for such things as delay or level of service in a roaming environment.

Ultimately, operators will have to offer customers the same level of service while they're roaming in foreign networks, in terms of QoS and pricing, as they get at home.

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