Ducker said the business services arm of UK cable market heavyweioght Virgin Media Inc, which is listed in the US but headquartered in Hook, UK, already offers a range of Ethernet services. In the Metro area, it offers a LAN extension service it calls Ethernet Extension. This is a very large proportion of our business, with tens of thousands of circuits, he said, describing it as a point-to-point fiber connection.
He said this service can be terminated with Ethernet switches at each end of the link, which removes the complexity of IP routers and in some areas its reach can go up to 90km compared to the 25km offered by UK incumbent BT on its LAN extension services. He said the services use technology from two German vendors: Pandatel and ADVA.
We also offer hub-and-spoke, i.e. point-to-multipoint services in the Metro area, said Ducker. There is also a Metro Ethernet VPN service that can be on shared or dedicated infrastructure, depending on the customer’s requirements, and is based on VPLS technology. That gives us the full gamut in the Metro, from point-to-point through point-to-multipoint to any-to-any, he said. We do a lot of any-to-any in the public sector, where we some customers require as many as 300 circuits.
We’re building smarts that are normally found in the IP layer into Ethernet, such as class of service and VLAN routing, he said. A council in Scotland has migrated its analog CCTV to IP CCTV on an Ethernet VPN, to which we’ve now added VoIP on a separate VLAN. It routes by MAC, not IP address and may even be delivering better performance because there is less routing overhead. The carrier uses technology from World Wide Packets for this capability.
All of these services can be delivered across its fiber rings in the Metro area. In the national arena, meanwhile, NTL:Telewest is offering point-to-point and point-to-multipoint services across its MPLS core. We present the traffic as Layer-2, route customers Ethernet packets using Q-in-Q for the access layer, then tag them for MPLS across the core, then strip the tags out at the other end, revert to Q-in-Q and then Ethernet at the other end, said Ducker. As well as being marketed to business customers, it is also used as the access layer for an IP VPN service, in which case it will require a router at each end.
The next stage on NTL:Telewest’s roadmap for its services is any-to-any Ethernet on the national level, and this is where it is considering PBT, a pre-standard technology developed by Nortel and championed, among others, by BT as a cheaper way of delivering services compared to end-to-end MPLS with Pseudowire circuit emulation (the Cisco alternative) or T-MPLS (the Alcatel proposal).
The historical obstacles of Ethernet for the carrier market are being removed, so that the distinction between L2 and L3 is moving, as a result of which our positioning is changing, said Ducker. IP VPNs, whether over MPLS or not, are starting to reach their peak, and now Ethernet is in the ascendancy.
On its wholesale carriers’ carrier business, NTL:Telewest is developing an SDH-over-Ethernet service, which enables mobile backhaul in a way that native Ethernet does not due to its lack of good clocking capabilities. Ducker declined to reveal the vendor it is working with on the project because he said it has yet to finalize the deal. Again, PBT would be an option here, since Nortel and the other vendors in that camp such as Siemens and Extreme say the technology can be used for backhauling mobile traffic from base stations.
He said the question NTL:Telewest asks itself is: will we improve throughput with PBT or T-MPLS, or can we stick with our current infrastructure and still achieve satisfactory performance? The latter option would be preferable because it would avoid investments in further technology, and Ducker said NTL:Telewest enjoys a major advantage in this context. Because our business services are delivered on a network built for consumer services, we benefit from the fact that, while the consumer side’s network traffic peaks between 7pm and 11pm, there is a lot of available bandwidth during the day, which enables us to achieve great speeds. Daytime utilization on our core is still sub-25%, he said.
While the carrier will use its MPLS core for the nationwide any-to-any Ethernet service, said the product manager, the options for the access layer come down to VPLS or PBT. The first thing we’ll do is offer it as a standalone product for new customers, then migrate existing customers, most of whom are doing it today with [multiple] IP VPNs.
We may or may not use PBT, thanks to our existing performance characteristics, he said. By and large we’re achieving sub-20ms round trips, and on some routes it’s even better, in the sub-5ms range. He said all the leading vendors have visited NTL:Telewest to put forward their suggestions for the new service and a decision is imminent because we’re looking to go with an any-to-any nationwide service at the end of this year.
