Addition of 'dark fiber' increases network capacity

Over the summer, Tufts Computing and Communications Services (TCCS) increased Tufts' network capacity for academic applications by leasing "dark fiber" from the RCN Corporation, continuing a cycle of planned network upgrades.

"Dark fiber" is the industry term for unused optical network cabling. Leasing dark fiber allows TCCS to maintain its own network infrastructure by simply installing the equipment on-site.

Most significantly, dark fiber service eliminates the need for the customer to install its own underground cables, a process that can be expensive and time-consuming. Installing long range cabling requires regulatory approval, a process that takes a long time and requires a large outlay of capital.

Instead, the University uses RCN cables, and was able to build a high-speed network much more quickly and easily than if it had installed the cables itself.

Several reasons have driven the University to upgrade its network over the last few years, said Doug Herrick, an associate director of data networking operations for TCCS.

Professors working on distance learning projects between various Tufts campuses and other universities often use large amounts of bandwidth during multimedia collaborations.

Another impetus for increasing network capacity was the Music and Language Departments' heightened use of streaming media. File transfers of high-resolution images from the health sciences database also put an increased strain on the network.

Chief information officer and vice president of TCCS Bruce Metz envisioned an inter-campus network connecting Tufts' Boston, Medford, and Grafton campuses. The new contract with RCN allows Tufts to utilize one part of RCN's dark fiber capacity to create a triangle network between the three Tufts campuses, wherein each campus is linked to the other two.

Consequently, it has become much easier for students and professors on the Medford campus to access computing and multimedia resources located on other Tufts campuses.

Before the RCN contract was signed, the campuses had three disparate networks with low-speed links between them.

RCN's dark fiber capacity also allows Tufts to connect to Internet2, a very high-speed network linking more than two hundred universities. Internet2 allows the universities to develop advanced networking applications in a way that would be impossible over the commodity Internet _ the Internet with which most users are familiar.

Tufts has now become one of the first members of the Internet2 Commons, a group researching videoconferencing and real-time collaboration over the Internet. This research has increased the awareness of the feasibility of videoconferencing for students and staff.

Participation in the Internet2 Commons would not have been possible before the network upgrades over the summer, Herrick said. Members of the Tufts community also use Internet2 for other research projects in the areas of high-energy physics and statistical mapping.

A full disaster recovery plan was an integral part of the added dark fiber capacity. "We've tried to build a lot of redundancy into our Internet connections," Herrick said.

The University's multiple connections to Internet2 are one such precaution.

The University system can reach Internet2 through Northern Crossroads, Internet2's own service provider, as well as through two service providers on the commodity Internet.

If the Internet2 connection goes down, traffic is redirected to one of the other fiber connections and is carried over the commodity Internet. If the primary commodity service provider goes down, all traffic is diverted to the secondary connection.

As a final precaution, the dark fiber triangle network between the three campuses allows traffic to be redirected through the other two links if one goes down.

Looking toward the future, the added dark fiber offers Tufts a high level of flexibility in continuing to improve its network. Since the added capacity is provided through fibers that run between two Tufts-controlled locations, the University has total authority over how the capacity is used. By simply changing the optical networking equipment at these locations, Tufts can run as little or as much bandwidth as is needed over the fiber.

Currently, all of the dark fiber links run at one gigabit per second. A network running at full capacity at one gigabit per second could download the equivalent of a floppy disc's contents in 1.1 seconds. A 56k modem, through which most dial-up users connect to the Internet, would require 200 seconds to download a file of the same size.

According to Herrick, the links will be upgraded to run at ten gigabits per second, ten times faster than the current speed, as soon as the price comes down