What’s New in Carrier Ethernet Transport

Ciena, Meriton Address Relationship Between Ethernet and Optics

The popularity of Ethernet continues to snowball. The technology, which made its mark in local area networks years ago, since has caught on both as a business service and as an access technology to carry a wide variety of services on carrier networks — pushed along by its attractive price points and scalability. That and the growing number of IP applications on the network have created a shift of epic proportions in the telecom industry, which grew up in a very controlled environment based on static, connection-oriented technologies.

Now Ethernet appears poised to make its mark on the transport part of carrier networks, challenging such entrenched technologies as SONET and even MPLS, and creating what some see as new equipment categories.

For example, Meriton Networks earlier this year announced its entry into what it calls “the emerging carrier Ethernet transport market” by marrying Ethernet and WDM in its 7200 OSP (Optical Switching Platform), an integrated switching and transport system.

FlexSelect Architecture for Carrier Ethernet Click Enlarge

This solution addresses two key trends evident in metro networking today, according to Ken Davison, vice president of marketing and business development at Meriton. The first trend is that Tier 1 service providers are trying to drive down network costs and enable new services by consolidating multiple networks on an IP service delivery platform and putting all that over new transport architectures. The second is that investment in SONET and SDH (which Meriton believes will remain as a client interface) is being phased out in favor of other transport architectures. Meriton believes WDM and optical transport layer (OTN), the switching capability associated with WDM, will be the transport architectures of choice going forward.

As a result, Meriton says carriers will be able to reduce metro “headend” (gigE) port consumption significantly, and reduce the requirement for a separate Layer 2 aggregation platform between the optical and packet layers. By keeping the switching in the optical domain, carriers can achieve a deterministic QoS, low-latency, low-jitter approach for switching carrier Ethernet traffic. Additionally, keeping traffic in the optical transport domain wherever possible minimizes tributary handoff and the number of Layer 2/Layer 3 hops. It also allows for end-to-end path management of individual gigE optical paths, with point-and-click provisioning, protection, and bridge-and-roll functionality, while optimizing fiber usage, the company says.

Phase one of Meriton’s plan will enable carriers to support gigE networking within the metro using sub-wavelength switching and grooming of nine gigabit Ethernet streams onto a 10gbps wavelength. The capability of switching a gigE path within the optical transport layer and maintaining the path throughout the entire network and assuring it with an SLA makes it ideal for wholesale interconnect services, according to Meriton.

Ciena’s Mitch Auster

During phase two of Meriton’s carrier Ethernet transport equipment rollout, the company expects to introduce support for Carrier Ethernet tunnel switching and aggregation for local handoff. PBT, or provider backbone transport, will be the first Ethernet tunnel technology to be supported by Meriton. PBT, which xchange wrote about in its February issue, is expected to have a significant impact on the transport transformation discussion in its own right. It currently is undergoing ratification within the IEEE, under the proposed name of provider backbone bridging – traffic engineering (PBB-TE).

Both phases will be available in Meriton’s 7200 OSP in the second half of 2007.

Ciena Corp. also recently addressed what’s happening with metro transport with some new product and architecture announcements. The company has introduced two new products, a road map for its existing transport and switching series line, and its Ethernet vision for FlexSelect.

FlexSelect is the architecture Ciena introduced in 2005, but now the company is integrating packet transport directly into that and extending the solution to the customer premises and the service edge, says Mitch Auster, senior director of service provider solutions marketing at Ciena. “This is driven by a recognition, which maybe comes from service providers that have been deploying Ethernet for the longest, that service providers are reaching a point where they can’t scale the network from a manageability perspective and maintain the profitability they need. So they need to converge services on one network,” says Auster.

The new solutions from Ciena will allow carriers to use their metro networks to aggregate traffic to fewer, higher-speed connections; use every bit of their wavelength flexibility; use connection-oriented Ethernet so they can pack as many services as possible into the transport layer without overburdening it; and avoid sending traffic through multiple packet engines, instead doing packet aggregation and switching at intermediate offices. Ciena studies show that this approach can lower carrier ownership costs by up to a third, according to Auster.

The alternative, he says, is continuing to try to scale Ethernet over SONET, or deploying IP MPLS routers and directly connecting them with WDM, which Auster says Ciena believes is too complicated.

Cisco Systems Inc.’s Ian Hood, marketing manager for service provider solutions, says that: “At the moment, in the aggregation network, people are using IP over MPLS because the traffic is not as well known. That’s now the best way to go based on current equipment and standards. But going forward, there may be a move to Ethernet over WDM or Ethernet transport over MPLS — which we already do now — with other technologies as they come along.” However, adds Hood, there are still open questions about how to handle redundancy, scaling, and unicast and multicast traffic requirements in these newer transport scenarios.

“The Cisco model, I believe, is very focused, of course, on routing — intelligent routing,” says Erin Dunne, director of research for research firm Vertical Systems Group Inc. “Whereas the Etherent — direct Ethernet over the optical transport, such as a Meriton would be doing — would be eliminating [the need for] some of the intelligence in the routers because you would have intelligent switches, which in [Meriton’s] eyes is better, faster and cheaper.”

Of course, today’s transport layer includes a lot of SONET, WDM and MPLS, she adds. “It is early on in this debate, but you’re talking about some religious warfare here — big carriers versus small carriers, MPLS versus not, SONET versus not, do you want to go with the Cisco model or the carrier Ethernet overlay model? There are pros and cons to each one.”

xchange will provide more details on the MPLS-related aspects of this discussion — including more PBT, as well as T-MPLS, commentary — in the May issue.

Share this article: Email, Slashdot, Digg, Del.icio.us, Yahoo!MyWeb, Windows Live Favorites, Furl
Add this article feed to: RSS, My Yahoo, Newsgator, Bloglines