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Backbone providers woo cable

Thu, 02/28/2002 - 7:00pm
David Iler, Contributing Editor

Many cable TV engineers were forced to switch into crisis mode as the rapid deterioration of the Excite@Home relationship with the industry demanded swift action to move hundreds of thousands of data subscribers onto new networks.

Perhaps the most dramatic accomplishment was what Mike Jenner, vice president of global IP network services for AT&T Business, calls the "six-day miracle" –the migration of 850,000 AT&T Broadband data customers from the Excite@Home network to AT&T's own backbone. (AT&T's switchover efforts were covered extensively in the February 2002 issue of CED.)

Figure 1: The Global Crossing ATM Fiber Network.

Yet more than playing the role of superhero to save the day in the face of near-term calamity, fiber optic network providers, including AT&T, Level 3 Communications Inc., Sprint Corp. and Global Crossing Ltd., are pitching technologies beyond raw bandwidth and connectivity to help operators wade into future service offerings, including multicasting, business services and IP voice. The arrows in the quiver of these fiber providers are stamped with an alphabet soup of emerging protocols and technologies.

Ol' reliable

AT&T Broadband was not the only cable operator to turn to AT&T Business. Jenner says the company has signed deals with a number of other providers, both announced and unannounced, for a full set of IP services that the company offers, including IP backbone managed services, managed regional networks, IP routing and provisioning systems. A deal with Mediacom Communications Corp. was announced in January, involving yet another Excite@Home migration.

To a large degree, AT&T Business relies on the brute force of its OC-192 (10 gigabits per second) North American IP backbone, which extends to 600 high-speed points-of-presence, each capable of supporting OC-48 (2.5 gigabits per second) connections.

In addition to these services, however, AT&T Business also offers its Intelligent Content Distribution Service (ICDS), which, according to Walter Sturm, ICDS product manager, is geared toward pay-per-view and video-on-demand IP services. Sturm says the service is in trials with "content owners that are network companies," although he declined to name names. On the client side, the service uses an electronic ticketing technology that places or provides a "cookie" to the end user, which allows the content to be accessed based on subscription priority or other parameters.

On the network side, Sturm says content is distributed out to nine hubs, which reach out to various Internet points. This contrasts to a "co-location overlay architecture" employed by the likes of Akamai Technologies Inc., which relies on caching content on hundreds or thousands of nodes. Sturm notes the efficiencies of delivering content to only nine sites from the origination server, instead of exponentially more edge locations.

New kid on the block

While AT&T Business has a natural opening to pitch its wares to the industry based on its relationship with AT&T Broadband, the door has not been closed to other providers. A good example is Level 3.

"The cable industry is an industry we work very closely with," says Dan Caruso, group vice president of Level 3's network business. Indeed, "the @Home transition created a nice opportunity for us," he added, letting Level 3 step up to the plate in a time of need.

Figure 2: AT&T Intelligent Content Distribution Service, Domestic Infrastructure. AT&T doesn’t reveal the exact locations of
all of its nodes for security and proprietary reasons.

In January, the company announced network service agreements with Cox Communications. The deal provides Cox with broadband infrastructure services to support its 780,000 residential and business high-speed data customers.

Last summer, Level 3 inked a deal with Adelphia Communications' Adelphia Business Solutions division to provide (3)Link Global Wavelength service. Level 3 will be providing 2.5 gigabit-per-second wavelengths along nine inter-city routes connecting Chicago, Denver, Los Angeles, Philadelphia, Phoenix, San Francisco, San Jose and Seattle.

Phil Jackson, vice president of commercial development for Level 3, citing the common operator dilemma of "do we build or do we buy" with regard to backbone infrastructure, believes that a key factor in winning Adelphia's business was Level 3's ability to provide the operator with a wavelength backbone network in a quick fashion. Boosting this functionality is Level 3's On-Net Transport Activation Process (ONTAP), which is essentially an intelligent operational support system that auto-recognizes network inventory for provisioning. A component of ONTAP is a Web-based order-entry system that lets customers check for available routes relative to their points-of-presence.

As Chris Kenny, director of product management for Level 3, points out, a key part of engineering a network for a customer is determining where those points-of-presence are (the actual street addresses) and connecting them together.

Cox purchased Level 3's (3)CrossRoads Internet access and (3)Center Colocation service in five U.S. markets. In addition, Cox is using Level 3's OC-48, 2.5 gigabits-per-second (3)Link Private Line and metropolitan dark fiber services to link its regional data centers and metro fiber networks to the Level 3 network. Essentially, "we're interconnecting with their backbone to get Internet connectivity," says Jay Rolls, vice president of data engineering for Cox. In this way, Cox data subscribers will traverse the Level 3 network to get to sites hosted by Level 3 or to use Level 3's peering points to other so-called Tier 1 Internet backbone providers. The arrangement with Level 3 is also meant to augment Cox's business services division's national connectivity.

Turning to MPLS

Level 3 is a big proponent of Multiprotocol Label Switching, a fast-emerging routing technique that improves upon best-effort packet delivery by, in a nutshell, using small "labels" in packet headers to route packets to their proper destination. MPLS-enabled routers use these labels to determine destination and delivery priorities, forgoing digging deeper into the packets for destination information, as is the case with traditional IP routers.

ONTAP system
Figure 3: Level 3's Web-based ONTAP system lets customers quickly design and provision their own wavelengths, private-line
circuits and other services.
ONTAP system
MPLS serves as the underlying transport technology for the Level 3 network, says Jackson. With MPLS serving as the common backbone infrastructure, multiple communications streams, including video streams, voice traffic, gaming sessions requiring low latency, and Virtual Private Network sessions can all be carried on a single network.

In the future, Rolls anticipates that MPLS may be deployed in the Cox portion of its network to bring value-added features and services to commercial customers. For example, using MPLS, an operator may provide access to a commercial customer in its franchise area to that customer's sites that may reside outside the franchise, in another provider's territory. Yet Rolls sees the actual implementation of MPLS in the Cox network as being from 18 to 24 months into the future.

Another competency Level 3 brings to the table, and a key part of its strategy, is its soft-switch services, enabling IP-voice and back-office support services at the core of its network. According to Caruso, Level 3 has engaged in a "fair amount of dialogue" with the cable industry about this capability. In 1999, Level 3 purchased XCom Technologies Inc., and Level 3 took the code it inherited and built it into its network, together with soft switch technology from the Sonus Networks Inc. platform.

Native multicast support

With an eye toward emerging multicast applications such as streaming media, Sprint Corp. touts its support of native multicasting on its backbone. More specifically, Wil Walkoe, director of Sprint's corporate technology development group, notes the network's support for Internet Group Management Protocol (IGMP), which is included in Cable Television Laboratories Inc.'s Data-Over-Cable Service Interface Specification (DOCSIS) 1.1 protocol. "Sprint has a significant lead in this area," says Walkoe.

At its basic level, IGMP is used by IP hosts to register dynamic multicast group membership, and by network routers to discover group member's IP addresses.

Sprint actually operates two network configurations. One was engineered for the now discontinued ION service, equipped for multi-service IP capability with managed Quality of Service on an Asynchronous Transfer Mode (ATM)-based network that evolved to MPLS. In addition, Sprint operates its traditional, IP SprintLink network, which doesn't rely on ATM or MPLS, but instead is engineered for very low occupancy with low packet loss rates and roundtrip delays.

Multicast is enabled on SprintLink; specifically, so-called "single-source" multicast based on IGMP, version 3. This means "any given multicast group can only have one sender," says Walkoe. "If your network also supports multicast capability. . . you can extend multicast all the way down to the end user," Walkoe points out. Using techniques such as sparse mode protocol independent multicast, the network can adjust to optimize the delivery path as more people join the network.

"Up until now, there was only one way cable could do a multicast–they had to do it themselves," says Walkoe, meaning that the content had to originate at the headend. With a multicast-supported network, a third party, such as a content provider, can originate the content, freeing the operator from storing the content on its own servers.

Interestingly, Walkoe points out that "multicast is much easier to implement without MPLS," which relies on establishing explicit paths on the network. With a multicast event, the sender doesn't know who's going to join the multicast–and paths are undetermined at the outset.

Digital video over fiber

Global Crossing's January bankruptcy filing, made as business partners in Asia invested $750 million in the company, didn't prevent it from recently rolling out a digital video transport service over its ATM network last month.

Currently, Global Crossing supplies digital video transport services to CNBC Europe. The service, says Chris Spacone, director of engineering for digital media services for Global Crossing, is essentially a satellite bypass over a terrestrial network for three channels of content moving from New York to the United Kingdom via Global Crossing's undersea fiber network.

The new service, says Spacone, can "help MSOs tie together systems in different operating areas." An important aspect of the service, he says, is the network's ability to move ASI-based payloads (ASI being the transport scheme used by MPEG-2). Global Crossing can take an ASI payload in its native format, including an entire channel lineup, off a satellite receiver without having to re-encode the MPEG-2 stream and move it between two points.

With its global fiber network, Global Crossing can move video content between areas where a satellite footprint is limited. Spacone notes that some programmers and networks are interested in moving regional TV content, for example Asian content, into the U.S. for rebroadcasting–a task suited for the new service. In addition, utilizing the video transport service, operators can target specific on-demand or pay-per-view content to selected cities using the ATM network.

Patching cords quickly

Beyond residential and commercial data services, the cable industry will likely be turning to managed IP backbones for a major service it has long planned for–PacketCable-based voice services. Yet, according to Cameron Gough, vice president of advanced voice services for AT&T Broadband and a member of PacketCable's business team, it's too early to tell how operators will develop a backbone for IP voice, although QoS and low latency will be key attributes.

Similarly, other advanced services requiring long-haul connectivity still remain beyond most cable operators' near-term focus, making quick response to customer needs, rather than support for emerging protocols, vital as IP backbone connectivity is weighed. "In this situation with @Home and the urgency of it all, the ability to respond rapidly was absolutely paramount and was probably the number-one factor" (behind Cox's selection of Level 3), says Rolls.

"There's still an amazing amount of brute force in all of this," says Rolls. "It's people pulling cables; it's people splicing; (it's) rack termination, cross-connects."

Not as sexy, perhaps, as new routing protocols and multicasting, but until new Internet-based applications and services take hold, it's likely that ensuring basic connectivity in a timely fashion will be the attribute that turns the heads of cable's engineers.

E-mail: editor@denver.net

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