Some researchers have proposed plans in recent years to reimagine what the Internet would look like if you started with a clean slate. Others, like those within the systems and networking group at Princeton University's Computer Science Department, are inventing ways to make the Internet more flexible for data center operators and more useful to mobile users by slipping technology in between layers of the current architecture.
Princeton's open source Serval system is what Assistant Professor of Computer Science Michael Freedman calls a Service Access Layer that sits between the IP Network Layer (Layer 3) and Transport Layer (Layer 4), where it can work with unmodified network devices. Serval's purpose is to make Web services such as Gmail and Facebook more easily accessible, regardless of where an end user is, via a services naming scheme that augments what the researchers call an IP address set-up "designed for communication between fixed hosts with topology-dependent addresses." Data center operators could benefit by running Web servers in virtual machines across the cloud and rely less on traditional load balancers.
Freedman, who heads the Serval team and is a recent recipient of a Presidential Early Career Award for Scientists and Engineers, says Serval initially is in the form of a loadable Linux kernel module for Linux and Android systems, though can also work with Mac and Unix-based systems, and translators have been implemented that could keep Windows machines in the loop, too. Hardware blades could be fashioned from the technology down the road as well, he says.
"One can think of this as an overlay, but really, it means there is some software running on machines that act as service routers (much like DNS resolvers/nameservers or DHCP servers," Freedman says. "These are only 'on-path' for the first packet of each flow, unlike today's load balancers, which must be on-path for each packet."
Serval, which Freedman describes as a "replacement" technology, will likely have its first production applications in service-provider networks. "Its largest benefits come from more dynamic settings, so its features most clearly benefit the cloud and mobile spaces," he says. "That said, it certainly could be used in enterprise settings - one obvious way is that zero-conf service discovery (say as an alternative to DNS-SD and Apple Bonjour) is very natural in its model, even across Layer 3 domains."
If any of this sounds similar to software-defined networking (SDN), there are in fact connections.
Freedman worked on an SDN/OpenFlow project at Stanford University called Ethane that was spun out into a startup called Nicira that VMware just plunked down $1.26 billion to acquire. Freedman recently found himself congratulating his former Ethane partner Martin Casado, Nicira's CTO. "Rather than help start Nicira in 2007, I decided to join the faculty at Princeton," Freedman says.
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