Global Crossing migrates to packet-based voice

Dec. 1, 2000



Global Crossing Ltd. (Hamilton, Bermuda) has begun the move from traditional circuit-switched voice traffic to carrier-class packet-based voice-over-Internet Protocol (VoIP). The company lit the first portion of its VoIP backbone last September between gateway centers in Atlanta; Chicago; Dallas; Kansas City, MO; Rochester, NY; and Seattle. By the end of this year, core VoIP gateway centers will be operating in a total of 15 U.S. cities and seven European locations.

By the end of 2002, Global Crossing expects to integrate all of its voice traffic onto its 162,500-route-km global IP-based network, connecting 27 countries and more than 200 major cities. The company is deploying VoIP as a services layer for voice services and applications.

"Our VoIP services layer rides directly on top of our global fiber-optic network and thus enjoys the same seamless network benefits," says Allan Van Buhler, vice president of global product development for Global Crossing. "The benefits include high quality, as the network is engineered and managed end-to-end by one company. Without the need for negotiating with other companies for handoffs and routing instruction at interconnect points, traffic can be transported very fast. Flexibility is also a key feature, allowing customers to provision and manage their own services on a worldwide basis."
Global Crossing's voice-over-Internet Protocol (VoIP) services run directly on top of the company's global fiber-optic network. By the end of this year, most of the voice traffic from the U.S. and Europe will be migrated from circuit-switched to packet-based services. Global Crossing plans to eventually deploy VoIP service across its entire worldwide network.

The VoIP network is engineered for up to OC-48 (2.4 Gbits/sec) but is capable of scaling to OC-192 (10 Gbits/sec) levels and beyond. Since VoIP will run over a privately engineered network, Global Crossing will provision capacity on an as-needed basis-unlike many other carriers that must go to someone else to purchase their capacity.

In 1999, Global Crossing established a development network, DevNet, connecting Denver, Detroit, Rochester, and most recently, London. DevNet is a physical VoIP network that replicates the production network. Global Crossing uses DevNet for product development and testing prior to loading equipment into the production network. That provides several advantages in terms of deploying new technologies quickly.

"First, we're able to do regression testing and ensure high quality before actual deployment," says Van Buhler. "Second, we can develop and test the actual process for loading into the network. This allows us to upgrade the network without any impact to customers. Third, we're able to do very aggressive testing. We purposely try to crash DevNet to see how the network reacts, what the network-management systems do, how the redundancy works, and how well the network elements recover."

Van Buhler says DevNet enables operations people to observe and learn. Through vigorous testing, problems are solved proactively and personnel are trained more efficiently to understand and react quickly to any problem in the production network.

Global Crossing is using packet-telephony equipment manufactured by Sonus Networks (Westford, MA), including the GSX9000 open-services switch, the PSX6000 softswitch, and the SGX2000 SS7 signaling gateway. Following extensive testing, Global Crossing chose the softswitch for its ability to scale approximately 25 times more efficiently than the other products.

The relationship between these two companies sprang from Sonus's original relationship with Frontier Communications, acquired by Global Crossing in 1999. Sonus delivered its first beta units to Frontier for testing and was ultimately selected to provide its GSX9000 product, while Lucent Technologies (Murray Hill, NJ) provided a softswitch. The relationship with Global Crossing eventually resulted in Sonus providing its entire packet-telephony suite throughout the global network.

Sonus describes its equipment as an "any-to-any" voice-over-packet central-office switching platform that meets carrier demands for interconnectivity, capacity, reliability, and voice quality. "The term 'any-to-any' refers to a switch's ability to switch calls from packet to circuit as well as circuit to circuit," says Gary Rogers, vice president of worldwide sales and marketing at Sonus.

This capability is a big part of enabling carriers to generate new revenue streams through the use of packet telephony. Rogers points out that packet telephony can facilitate applications that are difficult or impossible to deploy when voice and data ride separate networks. It can also accelerate time-to-market for new applications.

"Carriers will need to offer the services already common in the voice network, such as voice mail, call forwarding, caller ID, and so forth," says Rogers. "But the explosive growth of the Inter net also demands services that will bridge the two worlds."

Examples of such services would include unified communications and Internet "click-to-talk." These services have been slow to develop, largely due to the separation of networks for data and voice traffic. Network convergence could lead to elimination of barriers and yield a flood of innovative new services, Rogers believes.

"From an application-development perspective, applications for the PSTN [public-switched telephone network] have traditionally been a slow and costly process," says Rogers. "Services are implemented either in the circuit switches themselves or in separate processors called service control points [SCPs]. Carriers are often dependent on switch vendors for enhancements, with changes taking up to several years and costing millions or tens of millions of dollars."

In contrast, Rogers says Internet applications are developed in months or even weeks on inexpensive, standard hardware platforms using commercially available tools. Packet telephony takes advantage of the rapid developments in IP technology to improve on time-to-market and overall cost-effectiveness for telephony applications.

There can be significant advantages in VoIP transport, contends Global Crossing. For example, a circuit-based time-division-multiplexing call uses 64 kbits/sec. Depending on packetization, a VoIP call can use as little as 6.4 kbits/sec. When there is silence, no VoIP packets are generated or transmitted. From a cost perspective, platforms are about half the cost, with physical footprints about one-tenth the size. More than 50% can be saved on recurring costs such as building space and power.

Across the telecommunications industry, a battle is still being waged over which protocol, ATM or IP, provides the highest quality in terms of packet delivery. Global Crossing contends its position is enviable when it comes to understanding the differences, since it has both ATM and IP carrier-class networks riding its fiber-optic backbone.

"Today, we're utilizing ATM to ensure highest quality across our IP backbone," says Global Crossing's Van Buhler. "However, we have and will continue to deploy the latest IP technology available to ensure continued highest quality across our IP backbone. Having one of the world's largest privately engineered IP backbones, we tend to get the most advanced technology first. In the end, IP is a unifying protocol. What starts out as IP on the desktop and ends up as IP on the desktop should stay as pure as possible to the originating and terminating protocol in the middle. As technology continues to advance, once achieved, all will use it."

Besides Sonus, Global Crossing has several other partners involved in completing its global fiber-optic network. Cisco Systems Inc. (San Jose, CA) is supplying Ethernet routers, Lucent provides ATM switches, and Alcatel (Paris) delivers the SCPs.

Global Crossing's additional U.S. gateways, slated for operation by year's end, include Anaheim, CA; Detroit; Indianapolis; Newark, NJ; Philadelphia; Sacramento, CA; Tampa, FL; and Washington, DC. In Europe, gateways include Slough and Docklands in the U.K., as well as Frankfurt, Paris, Amsterdam, Copenhagen, and Brussels.

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