Ethernet Frame Relay

I’ve been talking to a lot of people about optical Ethernet lately, trying to determine just what it will take to create a profitable carrier service around this “new new thing.” Along the way, I met Roy Bynum, formerly of WorldCom Inc. (Nasdaq: WCOM), now an independent consultant working out of Texas.

Roy was the instigator of the 10-GigE WAN PHY, as well as a co-author of the X.86 LAP-S Ethernet-over-Sonet protocol and the X.86 Ethernet Flow Control Specification. He also was the architect of what is now commonly referred to as the Ethernet Private Line, which is, by most accounts, the only truly successful (read: "profitable") Ethernet-based service from a carrier today.

Roy is a big advocate of Ethernet. He sees it as not only the “next big thing,” but as the likely successor to the throne currently occupied by Frame Relay in the data networks of service providers – and by T3 on the transmission side of the house. This is big. It means Ethernet ultimately emerges as the winner in both transport and switching, just as it has within private enterprise networks.

Roy’s history lesson goes this way: A little less than a decade ago, Frame Relay overtook X.25 because it was cheaper for the service provider to operate and cheaper for the customer to own. Frame Relay could take a user up to 1.5 Mbit/s easily, which was big bandwidth at the time. Frame Relay service facilities are much more scaleable than X.25, thanks to encapsulation of customer frames in Asynchronous Transfer Mode (ATM) or Internet Protocol (IP).

That virtual switching fabric also allowed the service providers to distribute the Frame Relay access gateway facilities, which meant that the Frame Relay customer access did not need to be backhauled to large centralized switching points, making the local loop access a lot less expensive.

It also made it easier to build a redundant, diversely routed network architecture to support the interconnections among Frame Relay gateway facilities in different parts of the country. As history proved, Frame Relay was actually a better service, a better product, with overall better cost of ownership for both the service providers and the customers. Frame Relay opened up new markets for packet services by providing long-haul point-to-point and point-to-multipoint connectivity without the distance charges of private line or the volume charges of X.25.

For a while, people thought ATM would supplant Frame Relay once bandwidth demands from end users grew, but it didn’t: too expensive, too complex, violating the rules of low cost of ownership for carrier and customer alike. But along comes Ethernet, which today is appearing as an interface on just about every piece of data and transport networking gear in the service provider, after completely overtaking the enterprise.

Where Ethernet has already started to make an impact through simple Ethernet private lines (Ethernet mapped directly to Sonet channels), it’s worth taking some time looking at how Ethernet may just take over the packet services market as well. The form it takes may not be so different from Frame Relay, just faster and cheaper, and since Ethernet is based on its own set of standardized frames, it may make sense to just call this new service and infrastructure Ethernet Frame Relay.

The key, Roy argues, is Multiprotocol Label Switching (MPLS) encapsulation of Ethernet. No funny business with customer frames is allowed, giving users the utmost sense of security and giving carriers a way to carry that traffic without having to process it at anything other than Layer 2. Since the introduction of Frame Relay there have been several changes to the Internet Protocol standard that allows Layer 2 switching of end-to-end flows. This, in effect, creates a distributed switching fabric at the data-link layer, where before it was at the network layer. This should provide a much more stable and cost-effective way to implement the same type of encapsulated frame switching that was done for Frame Relay ten years ago.

Ethernet, the most commonly used protocol in the world, has matured in the last ten years. Legacy-free service providers experimented with providing direct Ethernet VPN (virtual private network) access to Internet services using Gigabit Ethernet as the transport protocol. Ten-Gig Ethernet has added a Sonet-like overhead to support managed optical wavelength services. The Institute of Electrical and Electronics Engineers Inc. (IEEE) P802.3ah Ethernet in the First Mile (EFM) Task Force is in the process of defining subscription network service-provider management support. Ethernet, instead of being only for privately owned enterprise networks, is now becoming a basis for building new types of revenue-generating data transmission services.

The advent of MPLS and EFM at the same time now makes it possible to provide the same kinds of networking services for Ethernet that were previously provided using Frame Relay. By using MPLS to encapsulate Ethernet frames, a distributed virtual switching fabric can be built for long-haul Ethernet point-to-point and point-to-multipoint links without having to pay long-distance private line charges. In addition, Ethernet/MPLS gateway switches can be distributed throughout metropolitan areas in large as well as small cities, making the virtual switching fabric even more distributed. This is exactly what is needed to create the next generation of wideband data transmission services.

MPLS has better QOS (quality of service) and bandwidth reservation capability than the older Internet Protocol that was used for Frame Relay. In addition to the ability to provide tiered bandwidth management to provide the same PIR/CIR (peak information rate over committed information rate) relationship, the use of Ethernet active flow control in the local access loop makes it possible to provide a more granular PIR as well.

Additionally, active flow control might be used to control the CIR/PIR relationship by using the MPLS forward and backward congestion control to generate a flow control message to the customer’s Ethernet switches on the ends of the access links. The active flow control message would slow the customer's transmission of Ethernet frames down to a level that prevents too much data loss during times of congestion. This will be a big help during peak business hours or at times when a fault in the transmission network reduces the service capacity of the distributed switching fabric.

With this, Roy Bynum believes, broadband access technology can be used to provide a wideband PIR for the narrowband CIR. Over a period of time, given the right market circumstances, it will provide an evolutionary migration path from wideband/narrowband packet service demand to broadband/wideband packet service demand and beyond. Where the need exists to use the existing copper local access infrastructure, 802.3ah is also defining an xDSL-based form of subscription network managed Ethernet. This wide variety of physical access standards will support the existing Frame Relay narrowband access as well as the growth to the high bandwidth of physical access.

See? That’s big. For enterprise customers without fiber ot the building, Ethernet-over-copper solutions get them on the network via a simple LAN interface. For those with access to fiber on metro optical rings, Ethernet access is already possible via Ethernet-over-Sonet or dedicated GigE links to service provider nets. Adding this encapsulation of Ethernet via MPLS is the final ingredient to taking Ethernet from an access service to a switched network service, where the real money is. Carriers haven’t ever been able to generate a lot of profits from packet services, just revenue. Something needed to come along and truly disrupt the cost of ownership of packet services to really get carriers serious about deploying broadband data services infrastructure. That means carrier spending, and that’s good for everyone.

— Scott Clavenna, Director of Research, Light Reading
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MP_UK 12/4/2012 | 10:25:58 PM
re: Ethernet Frame Relay Perhaps I've missed something here, but didn't a couple of carriers (Yipes & Cogent?) recently file for chapter 11 after trying to run a metro ethernet business? I seem to remember them getting a bit of a bashing on the message boards for their flawed business case. What's changed?

I'm not saying that widespread use of ethernet isn't a good idea - quite the opposite - but if it wasn't a viable business a couple of months ago, why is it now?

Come to think of it, I didn't notice any new concepts / information in the article, but maybe it wasn't written for LR's more regular viewers.
glass 12/4/2012 | 10:25:56 PM
re: Ethernet Frame Relay The problem with Yipes was the business model that was based on delivering only basic Ethernet services - kind of a one-trick pony. The difference between that and what the big players are planning is that the big guys want to offer Ethernet as one of the new services, along with existing services - TDM, frame relay, ATM, etc. This is why the ability to use the carrier's existing infrastructure (including SONET and fr/ATM)is a critical success factor. Ethernet service on an existing infrastructure is a no-brainer from economics and simplicity points of view, but Ethernet-only service on a new or overlay infrastructure as the business model is brain-dead.
gea 12/4/2012 | 10:25:47 PM
re: Ethernet Frame Relay What's described here is very different from the Cogent model, and (I suspect) different from the Yipes and other Ethernet-service provider models.

Cogent uses a fairly costly set of dedicated GbE links to a building. Basically, they map a couple of GbEs over SONET (using the 15454), and then optially multplex (if needs be) these EOS wavelength. At each location,on the GbEs is dropped out and fed to a location. It's basically a set of point-to-point GbE (or dual GbE) links over a metro area.

In this case were talking about a suped-up version of Ethernet that allows for the sophisitcated kinds of CAC, protection, and SLAs that ATM gives: for instance, it would allow a giant metro ethernet ring, with all customer's traffic entering and exiting from one ring. This is very hard to do without something like MPLS or other tricks.
jamesbond 12/4/2012 | 10:25:46 PM
re: Ethernet Frame Relay So why wouldn't somebody just use an all-optical
(i.e. transparent) transport boxes, connect
them on a ring. Drop 1GbE or multiple to
customers. Customer traffic comes in/out to/from
a GigE switch whose ports are connected to one (or more of) the Add ports on an all-optical transport box.

You can overlay multiple networks on such a ring.
Use n wavelengths for data network, m wavelengths
for your SONET traffic etc.

Bumper_car 12/4/2012 | 10:25:46 PM
re: Ethernet Frame Relay The problem with Yipes business model is that did not know what the end customers were willing to pay for. What does not come out in this article is that there never was an end customer demand for high bandwidth packet services. Since the only services that the ELECs could provide, given the limitation of the lack of out of band OAM, was packet services, they did not have a sustainable market, at any price. Applications, both business and personal are designed to optimise the amount of bandwidth that they use. End customers simply do not have the need for high bandwidth packet services today. That is the reason that mass market packet services is provisioned more at 128Kbps than at any other bandwidth rate. Even Ethernet Frame Relay will have to start in the low bandwidth narrowband/wideband market, not the broadband market that does not exist.
Bumper_car 12/4/2012 | 10:25:45 PM
re: Ethernet Frame Relay The real problem with any service deployment is return on investment. Only if you have customers that are willing to pay for something can you generate revenue. The customers are only will to pay for something if they believe that they will make a lot more money from something than what they are paying for it. Business owners are very pragmatic people. They have no religious belief in the greatness of one technology over another. The buy connectivity because they have applications that need it. They bandwidth based on a budget. The budget is based on their own return on investment. Their return on investment is based on their cost of ownership of the network and applications versus the revenue that the applications generate for them. Good business people, end customers of service providers are much the same everywhere.
Roy_Bynum 12/4/2012 | 10:25:42 PM
re: Ethernet Frame Relay Bottom line, the traditional Ethernet people, believing in their own way of doing things ignored the traditional data communcations end customers and their way of doing things. Instead of migrating or evolving the customer bandwidth needs profile, they wanted to create a whole new way of doing things. They wanted to be able to ignore sound business practices. They forgot that there was a requirement for a return on investment on the part of the end customers as well. They did not know what the end customer was willing to pay for, what it would take to deliver it, and where the optimal crossover was between cost to the customer and cost to the service provider provided optimal return on investment for everyone.

The ELECs were dreamers, not good business people. There is nothing wrong with being a dreamer, but dreams do not always create sustainable business or service models.

What I have suggested, Ethernet Frame Relay (EFR), Ethernet at low bandwidth rates over legacy physical plant for packet services will supplant the existing Frame Relay. Starting with Ethernet over copper access into the EFR gateway, cost of the CPE gets reduced which will reduce the cost of ownership for customers using the same types of services that they are today.
jshuler 12/4/2012 | 10:25:38 PM
re: Ethernet Frame Relay Full encapsulation of Ethernet frames without manipulation. Labels, CIR/PIR/MBS, in and out of profile, CAC and flow control. Just like RPR.

The key is to use exactly what you need and no more.

Sounds like we are all converging on something here.
Roy_Bynum 12/4/2012 | 10:25:37 PM
re: Ethernet Frame Relay Full encapsulation of Ethernet frames without manipulation. Labels, CIR/PIR/MBS, in and out of profile, CAC and flow control. Just like RPR.

The difference here is that MPLS will work in a mesh network, which is what the ILECs/RBOCs/CLECs have and what the virtual switching fabric of Frame Relay is today. RPR is restricted to ring architecthures. RPR would require a 100% new deployment which is not likely to happen. Ethernet over MPLS/IP can use the existing infrastructure with additional devices at the edges, and only perhaps some new switches in the core. RPR does not scale very well into a large mesh of rings. Ethernet Frame Relay will require a vary large semi mesh if the service is to scale beyond where Frame Relay is today.
fiber_r_us 12/4/2012 | 10:25:35 PM
re: Ethernet Frame Relay The problem with the Yipes business model was not Ethernet. It was that thier model required fiber to every customer (maybe because they wanted to bypass the LEC stranglehold on TDM circuits). If Yipes had decided to do SONET, RPR, ATM, FR, or *anything* to customers that required getting dark fiber to the customer's premise, the business would have still failed. Yipes' problems were not protocol specific, it was related to there being no easy (and cheap) way to getting fiber across the last mile.
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