Nashville's Internet Traffic Success

Nashville, Tenn., has its own cul-de-sac on the Information Highway, which provides a path to the main highway without exposure to a lot of unnecessary traffic.

by / April 30, 1996
PROBLEM/SITUATION: Nonlocalized traffic and
shrinking IP address pools are clogging the Internet.
SOLUTION: Nashville and the private sector have joined forces to regionally segment the Internet.
JURISDICTION: Nashville and Davidson County, Tenn.
VENDORS: Bell South, Data General.
CONTACT: Mark Lynam, information systems division manager, 615/862-6300.

The Internet is slowing down. Rapid growth has increased congestion and shrunk the number of available IP addresses for new users. The Internet -- once primarily a text-oriented transport medium -- is now carrying graphics, video and audio traffic, which extracts its toll in bandwidth and contributes to the slowdown.

Another problem is the indeterminate nature of Internet routing, which often requires many router "hops" before the data arrives at
its destination. For example, e-mail between two users in the same building in Mobile, Ala., might be routed through Seattle and Buffalo. As the Internet continues to grow, this type of nonlocalized traffic will further degrade network performance.

Part of the solution may be to segment portions of the Internet through regional routing. Regional routing provides a container for local traffic -- improving file transfers between local users -- and improves overall network performance. When the Metropolitan Government of Nashville planned its network, regional routing was selected as a strategy. Gus Alfaqih, information systems director and CIO for the Metropolitan Government of Nashville said, "You can't have a flat network and expect it to be efficient."

Under the stewardship of Mayor Phillip Breseden, the Metropolitan Government of Nashville and Davidson County established CityNet in 1994. CityNet is neither a government project nor a free network. Free-market economics and competition are the driving forces behind it. For as little as $10 per month a user can have a high-quality, dial-up account.

Several objectives were kept clearly in mind during the design phase. Low-cost, ease of use, and a solid design were key points of the project. By using standard Internet protocols and access methods, CityNet was able to blend seamlessly with the Internet. CityNet was designed to serve as a model for other communities attempting to implement their own networks.

The first phase of CityNet was constructing the basic network and building a consortium of people to manage the direction of the project. Members of this group came from both the public and private sectors. The combined efforts of Internet Service Providers (ISPs), the educational community and the Metropolitan Government working together made the project a success. ISPs continually work together and pool their talents to solve problems when they arise. Alfaqih noted, "The real genius behind it was the synergy that was created to bring these people together and work out all the problems." This concentration of effort has avoided many of the problems that have plagued similar projects in the past.

Using regional networking as a means to alleviate growth-induced problems in larger networks confines Nashville's networking tempest within its own teapot. Routing technology confines local traffic to the citywide network. By avoiding the main Internet, local traffic is not exposed to the rush-hour congestion and slowdowns that occur there. The router also blocks all Internet traffic not specifically addressed to a CityNet user. The result is less extraneous traffic on both CityNet and the Internet.

There is a continuing effort to install new servers to provide online information that wasn't previously available. These infrastructure improvements provide the support for information kiosks and terminals in public locations. Through CityNet, educational opportunities that did not previously exist are now becoming available to the public.

Initially, the management consortium was filled by appointments and voted-in seats. Future panel members will be installed from a voting process. With the first phase nearly complete, it is now time for Metro Government to step back from the project. Alfaqih said, "I want to get away from any connotation that CityNet is a government network, because it isn't. It is for the benefit of everybody."

Over the next two years, community information servers will begin to come online. The Metro Government will assist getting educational information, libraries, and other public service organizations onto the information servers. Local government information and services will be added to CityNet and made available to the public. Educational opportunities like Computer Aided Instruction with live audio and video will come online as the system matures.

"I think what we've done here is something that needs to be done across the country," said Alfaqih. "We're getting saturated on the Internet." Nashville's CityNet is a working blueprint of how to apply regional segmentation for the good of both local users and the Internet at large.


The heart of CityNet is the Connectionless Data Service (CDS) switched matrix device. This collapsed-backbone type of routing provides a central point of connectivity for seven locally attached ISPs and CityNet members. The CDS switch -- configured as a star -- connects the hubs of the ISPs and other CityNet users. Open Shortest Path First (OSPF) version 2.0 routing protocol is used by all ports directly connected to the CDS switch. OSPF was chosen because it is more efficient than Routing Information Protocol (RIP) for maintaining routing tables.

CityNet is capable of supporting a large volume of local routers. CDS does not in itself provide access to the Internet. Users wanting Internet access can set up an account with one of the locally attached ISPs. Each service provider maintains its own direct Internet connection and offers access through dial-up modems, ISDN and CityNet.

Locally attached users receive dynamically allocated IP addresses for use exclusively within CityNet. "Bell South has taken out a type of private Class-A address," said Alfaqih. "IP addresses are transparently assigned to the users." Internet users with an assigned IP address and domain name are unaffected by the locally assigned dynamic IP address. Alfaqih noted, "We don't cause any extraneous traffic to be put on the Internet."

Several connection options are available to users, including dial-up, ISDN and CDS. ISDN and CDS are services provided by Bell South. CityNet users can access community information, e-mail, file transfer, videoconferencing and library services.

Metropolitan Government staff gain access to CityNet through a single CDS connection. This separate port keeps their internal network private from CityNet. Linux is Metro Government's operating system of choice for both CityNet and Internet servers. It is a freeware UNIX work-alike that is both robust and efficient. Alfaqih observed, "It's a really solid operating system. You can't beat it."

Linux performed well as a UNIX replacement on a Pentium-class machine equipped with 64MB of RAM. Replacing UNIX with Linux on the same machine provided an accurate apples-to-apples comparison. "We first implemented our SMTP on a Data General machine running UNIX," said Alfaqih. "I really don't see any difference in delivery between the operating systems."