Core boost pushes edge developments

Huge leaps forward in network capacity at the core have left network suppliers with the problem of how to fill that fibre, so...

Huge leaps forward in network capacity at the core have left network suppliers with the problem of how to fill that fibre, so getting traffic on to the network from the edge is today's network battleground, writes Antony Adshead.

Taking the temperature of the optical networking market at Lightspeed Europe 2001 show in London last week, it was apparent that the hot topic is how to help operators to get closer to the edge of the network, where the core connects with the enterprise.

IT professionals will see increasing efforts by carriers to offer value-added services which result from advances in networking technology - storage switching, cheap and easy-to-manage virtual private networks (VPNs) which work at Layer 2, and packet prioritisation using multiprotocol label switching (MPLS).

Most of these developments are not directly powered by brute bandwidth - except for the rise of more flexible storage owing to bandwidth hikes powered by dense wavelength division multiplexing (DWDM).

One of the most important advances of recent years, DWDM has allowed carriers to pack 100 channels into a single fibre, giving a bandwidth of 250gbps per fibre. This means that storage networks can now be physically more independent of other elements of the corporate network because bandwidth between them is more readily available at low cost.

"Optical technology is changing the way IT directors think about the Internet," said Neil McCabe, channel manager at Lucent UK. "We have switches now that are tailored to putting storage over the carrier network."

Mark Lum of Nortel portfolio solutions agreed. "It used to be only Fortune Top 10 firms which could consider extensive storage networks but optical Ethernet has brought the cost down to affordable levels," he said.

The glut of capacity at the core is driving the search for ways to get traffic into it from the edge.

Steve Harbour of Native Networks said, "We have core networks of huge capacity. What the carriers are asking now is, how do we fill the fibre? That is why they are working towards the edge.

"But there is a problem. There is no economically viable technological solution to match delivery at the edge with capacity at the core so, currently, there are a number of standards and solutions trying to meet the need."

Native has positioned its strategy to smooth out this supply/demand conundrum. Layer 2 VPN technology is one part of its armoury. "Existing Layer 3 VPNs need boxes all along the network, whereas Layer 2 VPNs work at the transport layer and only need a box at the edge. It can be configured by the enterprise even, and it works out much cheaper," said Harbour.

"We are also starting to see the idea of managing bandwidth using MPLS technology, by the carrier as well as the enterprise," he added.

MPLS is a way of discriminating between packets so that different types of traffic flows, for instance storage data at key times in the business week, can be prioritised.

Harbour described it, from a technology viewpoint, as the end of democracy on the Internet, but the enterprise user may find the opposite is true as greater control is placed in the hands of the customer.

What is big in networking?
  • DWDM - dense wavelength division multiplexing is a way of boosting optical fibre capacity enormously. In the field, capacities have been increased a hundredfold and Lucent's Bell Labs claims to have already achieved 1,000-times increases. This has produced a glut of cheap bandwidth so that suppliers are now trying to match capacity at the edge with that at the core

  • Layer 2 VPN - a virtual private network routes data along a secured "tunnel" in the public network. Layer 2 VPNs require less reference to routing tables by devices in the network

  • MPLS - multiprotocol label switching uses labels that add forwarding information to IP packets. Routers examine the label more quickly than if they had to look up destination addresses in a routing table.

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