B-schools in the US and other developed countries have been providing intranet connectivity to hostels and student dormitories for quite some time. Of late, Indian institutes have also felt the need for such connectivity at their premises.

Indian Institute of Management, Lucknow (IIML), with the increase in student strength, began experiencing a growing strain on its computer center resources. In the beginning of 2002, the institute’s management decided to augment the campus network so that students could have intranet connectivity in their rooms. It was envisioned that this would encourage students to use desktop/laptop computers from their rooms, thus reducing the demand for resources at the computer center. The computer center, in turn, would be equipped with high-end clients for running limited license software, specialized mathematics/statistical software, and development tools.

Gigabit Network Design Issues
Although some inter-building multimode optic fiber links existed, the project—a gigabit networking one—was for all practical purposes a green-field project. It required laying of new fiber throughout the campus for interconnecting different hostel buildings. It was also decided to include about 61 faculty residences in this networking project, as this would help the faculty to gain access to the intranet resources, including the class material, office machines, the Internet and e-mail services from home. However, this made the network design much more complex as the houses are spread out. So suitable traffic concentration points were identified to be included in the backbone.

The network conceptualized in January 2002 had to be designed, implemented, and made operational by June 2002. The objective was to design and implement a scalable network that would require minimum sinking of the equipment and cables in use. And of course, it had to be a minimum-cost network.

Gigabit Ethernet versus ATM
In general, there are two options for very high-speed backbone networks—the gigabit Ethernet and ATM networks. ATM, while providing connection-oriented services, has in-built QoS features, and can support multiple classes of services with varying priorities. The biggest advantage of gigabit Ethernet over ATM is the seamless integration with the existing IEEE 802.3 compliant 10 and 100 Mbps Ethernet LANs. This is mainly because it was developed by the IEEE 802.3z Gigabit Task Force.

IIML team designed the network as a three-layer architecture.
The first layer includes one/two gigabit switches housed at the central locations, such as the computer center and the faculty block. These switches have UTP (1000 Base T) and fiber ports (1000 Base-SX) for connecting firewall and server farms.

They also have enough 100 Base TX/FX ports to connect to the existing 100 Mbps switch stack housed in the computer center. This is to make the migration of the existing fast Ethernet to the gigabit backbone easier.

The second level consists of backbone switches with Gigabit uplink ports to be connected to the Gigabit switches in tier-I, using 50/62.5-micron multimode fiber. The tier-2 switches are normally concentration points aggregating traffic from a group of hostel/residential blocks. These switches also have 100 Base TX/FXs ports to connect to information outlets or to other switches in tier-3. Tier-3 switches provide direct connectivity through 100 Base TX to the information outlets in various rooms.

Since the per-port cost of switches is not significantly more than per-port cost of a hub, IIML decided to go for a pure switched network configuration where the individual information outlets are directly connected to a switched port, giving a dedicated bandwidth of 100 Mbps. Further, the network was designed to be future-proof. Each information outlet is provided with a 4-pair category 5 UTP, so that it may become possible to switch to gigabit later on.

Most of the existing fiber was 62.5-micron multimode fiber, and hence could not be used for the Gigabit links due to distance limitations. It was decided to lay 6-core 50-micron multimode fiber for inter-block connectivity where the distance was more.

The 62.5-micron multimode fiber was used only for short hauls, especially across hostels within the same cluster. IIML decided not to go with single-mode fiber, as 1000 Base-LX ports were very expensive compared to SX ports.

Layer-3 versus Layer-2 Switches
Layer 3 switches can look at the IP address, for example, in making switching decisions. In this aspect they behave almost like routers. Since an L3 switch is approximately 25–40 percent more expensive as compared to an L2 switch, IIML decided to go for an optimal combination of the two types. L3 switches were chosen for both tier-1 and tier-2 while L2 switches were opted for tier-3.

Dilip Mohapatra, computer centre manager, and Dr V Sridhar, professor in-charge of computer centre, came up with broad network specifications and floated preliminary tender specifications in January 2002. Prospective vendors were asked to firm up their design specifications based on the inputs given by IIML. After completely reviewing the tender specifications of different vendors, CMC was awarded the contract.

Enterasys Matrix E1 switch, with 6-gigabit Ethernet ports and 48 number of 10/100 Base-TX ports, was selected as the core switch. SSR 2000, another higher-end L3 switch with 2 gigabit interfaces, 8 numbers of 10/100 Base-FX ports, and 16 numbers of 10/100 Base-TX ports was chosen at tier-1. Enterasys vertical horizon (VH) L3 switches were chosen for tier-2.

These switches have 24 number of 10/100 Mbps ports and a gigabit uplink to be connected to tier-1 switches. Enterasys VH L2 switches were selected at tier-3 to provide 100 Mbps switched connectivity to individual information outlets.

Project Implementation
The project started in mid-March 2002 and the implementation was completed by the end of May 2002, for a total cost of Rs 75 lakh. The annual maintenance contract for four years was also signed with the vendor for active components, such as switches and network management software.

Overall, about 4,000 meter of optic fiber and 30,000 meter of UTP cables were laid. At some locations, for interconnecting hostels within each block where the distance is less, fiber was terminated using a fiber-UTP converter on 100 Base-TX switch ports, in order to reduce the cost on the fiber ports on the switches. Around 800 information outlets were provided in various hostels and residences. Matrix E1 and SSR 2000 switches were chosen as the backbone switches as indicated above.

Around five L3 switches and 41 L2 switches were installed at various locations in the campus, 33 19" racks were deployed to house the switches, 39 patch panels for interconnecting information outlets to the switch ports, 16 LIUs, 17 fiber splices, 6 fiber-UTP converters were used.

Network Management
Virtual LANs (VLANs) have been defined over the switched configuration in portions of the network to keep a check on broadcast and unwanted traffic. VLANs also provide security to portions of the network, such as those of the faculty and the server farms. All the switches chosen are 802.1Q compatible, and hence are VLAN capable. VLANs can be used in the future when there is a need for QoS for different classes of traffic. Multicasting networks based on VLANs can also be designed to facilitate the use of group-based collaborative applications.

All the switches were assigned IP addresses, so that they could be managed from a simple network management protocol (SNMP) manager from the computer centre. IIML went in for Enterasys NetSite network management system (NMS) for managing the network. This was chosen over the widely used HP Openview due to cost reasons. Moreover, it was felt that since most of the switches were from a single vendor (Enterasys), it would be better to go for a proprietary product. Using NetSite, the network administrator would also be able to manage the existing Intel switch stack and the two Cisco routers.

IIML is planning to develop a comprehensive open source network management library, which will be used to augment NMS in future.

In the near future, firewall and some of the main servers will be augmented with gigabit network interface cards, so that they can be connected directly to the gigabit ports of Matrix E1 switch, thus eliminating network congestion problems.

The network went operational in phases starting from 15 June 2002, and by the end of July 2002 all connectivity problems were sorted out with help from the contractor. Dilip Mohapatra, computer centre manager, IIM Lucknow, says, "This was the single largest networking project I took up. I am glad that the project was completed on time within the allocated budget.

IIML is one of the few institutes in India which has deployed a gigabit campus networking, providing broadband connectivity not only to student hostels but also to all faculty residences in the campus."

Dr V Sridhar, associate professor (IT and systems), Indian Institute of Management, Lucknow