Some of the world's top network engineers are engaged in a research effort that could lead to the most radical redesign of the Internet's underlying routing architecture since it was developed in the 1980s.

The IRTF (Internet Research Task Force) is searching for a new routing architecture that would improve the Internet's ability to scale to support potentially billions of new users in developing countries. The IRTF is a sister organisation of the Internet Engineering Task Force, one of the Internet's leading standards bodies.

Under debate by the IRTF is how the Internet's backbone routers operate. Owned by carriers and some large corporations and government agencies, these backbone routers run the Border Gateway Protocol (BGP) to exchange routing information across the many interconnected networks that form the Internet.

The BGP routing table is a master list of network destinations that is stored in backbone routers and is used to determine the best available path from one network to another. Experts are worried about explosive growth in the BGP routing table, which is straining the processing and memory requirements of the Internet's core routers.

Why BGP growth matters

BGP routing table growth is significant because it drives up carrier costs, experts say.

"What CIOs really care about is the cost of their Internet connections, and if the cost of the service providers goes up because the routing table becomes unwieldy, that will lead to incremental costs for everybody," says Tony Li, co-chair of the IRTF's Routing Research Group. "We're interested in avoiding that scenario."

Slowing routing table growth would provide other benefits to enterprise network operators, too. It would make it easier to split network traffic over multiple carriers in a process called multihoming.

"One of the major causes of routing table growth is due to the pervasive practice of site multihoming," says Lixia Zhang, co-chair of the Routing Research Group. "Multihoming substantially increases the number of global routing table entries, and the Routing Research Group is working toward decoupling multihoming from the global routing table growth."

Zhang says another benefit will be easier renumbering of networks when enterprises switch carriers.

"One of our design goals is to eliminate the need for corporations to renumber their networks when they change providers," she adds. "Renumbering is considered a very expensive and complex process."

Seeking a new router architecture

The IRTF's Routing Research Group has existed for many years, but it was rechartered six months ago to look at future routing architectures.

As a sign of how serious it was about revitalising its Routing Research Group, the IRTF in February replaced former chair, Swedish professor Avri Doria, with two high-profile experts: uber router designer Tony Li, who has worked at Cisco, Juniper and Procket and is now back at Cisco; and Lixia Zhang, a computer science professor at the University of California at Los Angeles.

Since the Routing Research Group was revitalised, dozens of network engineers and researchers from around the world have participated in its thrice-annual meetings and online discussions. Among the network equipment vendors and service providers involved in the debate are Cisco, Juniper, Ericsson, Alcatel-Lucent, Huawei, AT&T, BT and Arbor Networks.

"The new focus of the working group is to work on a possible routing architecture that includes new ways of addressing, new ways of doing routing for the global Internet," Li says. "The IP address has both the identification of the node and the location of the node. The question becomes: Can we separate the identification from the locator semantics, and can we still run an Internet with that kind of architecture?"

The IRTF's Routing Research Group is "the most radical rethinking of routing ever," says Geoff Huston, a BGP routing table expert and chief scientist at the Asia Pacific Network Information Centre in Brisbane, Australia. "Routing and addressing are entirely connected concepts. They're joined at the hip. We did a significant rethinking about addressing when we adopted IPv6 [an upgrade to the Internet's main communications protocol, IPv4]. Now some of those ideas are resurfacing inside routing. We're looking at why we are routing and what we are doing."

Huston says the IRTF's Routing Research Group is considering making " a very, very big change for the architecture of routers. It has massive effects on the assumptions made in many applications."