Enterprise network

Enabling students to stay connected

IIT-Kharagpur has set up a converged IP network throughout its campus and introduced a host of applications to make education a fulfilling experience for its students

The Indian Institute of Technology-Kharagpur (IIT-K) wanted to deliver educational content to its students in a more flexible and organised manner, and decided to use IT as the enabler. With the assistance of its alumni, the institute set up a campus-wide converged IP network with over 4,000 access points that cover every hostel room.

The network offers multi-layered switched QoS, video-on-demand, multicast video, and the ability to host IP telephony in the future. The new multimedia-friendly network gives the 5,000 students on the campus unrestricted access to the network from their rooms without the need to be physically present at specific locations.

Strategic Need

One of the most reputed educational institutes in India, IIT-K recognises that information networks have emerged as strategic assets, and are a critical element for delivering education and services. The institute felt the need to provide state-of-art IP networking which could enhance the quality of the educational experience.

The objectives were to deliver live lectures and screen events with the help of IP multicasting, deliver high-quality video-on-demand to students’ hostels without affecting the network performance and bandwidth, standardise repetitive courses through video-on-demand, and provide opportunities to students and staff to pursue fields of individual interest in addition to standard course curriculum.

In a gesture of goodwill, the 2000-2001 alumni of IIT-K, many of whom are successful professionals in Silicon Valley, decided to provide funds for networking the student hostels on campus.

Planned Network

The campus already had a network based on Ethernet and ATM technology. Untouched by the network were 14 hostels in the campus. Each hostel is divided into two parts with 14 to 16 wings in each part. Each wing has 32 to 48 rooms per floor.

There was a suggestion to have a common room in the hostel with network outlets for all to share, but this would have created other problems since there were a large number of students. Another idea was to build a large network that would encompass all areas of the campus.

Planning and designing a network of this scale gave rise to a number of considerations which had to be kept in mind. They were:

The type of applications—there were plans to offer applications such as IP-TV through multicasting, video-on-demand, and mpeg2- and mpeg4-based live speeches, events and lectures.

Size of content—each presentation comprised rich audio and visual elements and was as long as an hour. As a result, the size of each file was large.

Geographical spread—the hostel buildings were spread over an area of 2.5 to 3 square kilometres.

Utilisation would be the heaviest in the evening after classes.

“Based on these considerations, the network design had to accommodate a robust backbone, high switching capacity, and strong load-balancing capabilities. It had to offer QoS so that traffic in one VLAN would not affect traffic of the other wing and the entire network,” explained Prof S Kumar, Faculty Member, Mechanical Engineering Department, IIT-K.

The network was segmented using VLANs to reduce collision of domains and broadcast domains, and deploy QoS in terms of the applications. “For instance, a person working on a site for educational research or collaborative study should be given higher traffic priority over an e-mail user or a music download,” says Kumar. This act of prioritisation does not restrict any network activity, but simply increases the time taken by a job with a lower priority.

The plan also intended that the network would use established industry standards and policies for the multiple VLANs and QoS to allow the best possible data rates and least latency.

Virtual LANs

14 to 16 access VLANs have been deployed at each hostel for individual wings. The network has been partitioned with smaller collision domains to provide high availability of network resources. This allows streaming multimedia (such as full frame mpeg-2 video lectures and distributed e-learning computing programmes) to provide shared whiteboard, chat and video simultaneously for multiple rooms at peak hours.

Two primary applications, video streaming and video-on-demand, were achieved through Cisco’s IP-TV solution. This solution provides the streaming audio and video content at data rates up to 80 Mbps on mpeg-2 and mpeg-4 in both unicast and multicast formats for the entire network. In-house e-learning content servers have been developed at the institute’s Centre for Educational Technology using the mpeg-4 standard.

The IP-TV Solution

The IP-TV solution has three components: the broadcast server, the archive server, and the control server.

A broadcast server helps to pre-plan the time of a broadcast to a select group. For instance, all computer science students staying in different hostel rooms can plan to attend a live lecture from an expert abroad at 7 pm. The broadcast can be planned in such a way that the media will only be distributed to the intended students in the multicast group at the specific time, automatically, without any reduction in network performance.

If a student who has missed a class wants to refer to the lecture or the notes given earlier, he can use the video-on-demand service for viewing the lecture. Although the size of the content can be huge, the network will automatically prioritise and balance load on the switches so that overall performance is unaffected.

The network uses content distribution managers to avoid effects of multiple media applications running on the network. This works with the help of content engines (at different locations) which push content to the nodes. Each hostel has a content engine which accesses the content load kept at a central location. The content is pushed from the central location to the content engine at the edges, so when a request for any media arrives, the content is fetched from the local content distributor. This avoids load on the backbone.

Network Components

There are 200-odd servers which converge to the core (8-10 Gbps capacity) of the network based on two Catalyst 6500 switches. This is connected to multiple distribution switches. Each hostel has a distribution switch, and the entire switching capacity is around 32 Gbps.

The Gigabit Ethernet LAN uses cables from D-Link. The servers are load balanced so that the same content can reside at multiple servers. If there is a request, and the data resides on multiple servers, a logical algorithm is used to carry the load across the switches to each desktop.

E-Learning

The network enables IIT-K to deliver a complete e-learning package comprising various audio and video formats to be broadcast to classrooms and hostel rooms. This has considerably enhanced the students’ academic activities and preparedness for industry. Every student has access to lecture material and virtual classrooms, and can conduct several projects and exercises online over the network. The network is also designed to cater to the QoS requirements of IP telephony. In future, the institute hopes to configure the network to enable students to make voice calls on IP phones and soft IP phones within the campus.

“The uniqueness is the scale and the range of applications. There are few educational institutes that offer access to such media-rich applications to their students,” declares Kumar. Another remarkable feature is the plan in terms of scalability design. If a new building or location is to be added, a new switch can be simply plugged into the network—and the network will auto-learn and configure itself a separate VLAN.