Welcome To Networks

SITA NOC The Computer Centre at IIT Madras was started in 1973 to meet the demands of the Institute for computational facilities. As the field grew, so did the computer centre - through the mainframe age on to mini computers, microcomputers, workstations and client-server systems. Today, the demand is not simply for computational facilities but has expanded into almost all areas of information technology support. Connectivity and networking have recently become key areas supported by the Computer Centre.The ERNET project was initiated by the department of Electronics, Govt of India in 1987. Under this project a LAN was established covering CSB and BSB. Subsequent to that, campus network was established by Computer Center.

The present campus network evolved from twisted pair cables, network for terminal connectivity to ATM based high-speed backbone. The Computer center takes care of all the network requirements in the Campus. During the installation of the Siemens mainframe system (1987), a need was felt to locate access terminals all over campus. Accordingly, communications cables were laid connecting the Computer Centre to most departments and laboratory buildings. Future expansion was thought of at this stage itself and the cables were laid in underground conduits. With the phasing out of the Siemens system, these cables and conduits became available for other uses. Simultaneously the easy availability of PCs at relatively affordable prices had led to several departments having local area networks (LANs) connecting the PCs and other computers within the building.

These LAN used shared Ethernet (thick or thin). Thus the LAN as a whole provides internal connectivity at 10 megabits/sec (Mbps) to be shared between all users within the LAN. The first inter-building connection was set up in 1994 using spare siemens cable with modems and routers. This provided a rudimentary network operating at 19.2 Kb/secs between some half dozen buildings. Very soon, this turned out to be too slow an interconnection speed and there was demand for higher speed connections. Using remote Ethernet bridges technology developed in the Electrical Engineering department, IIT Madras the first link of the campus network was set up in 1995 connecting the Computer Centre to the Aerospace Engineering building at a speed of 144 kb/secs. This scheme also used the spare Siemens terminal cables.

This technology was subsequently extended to other buildings so that by 1997, the campus network consisted of LANs in 18 buildings all connected at the Computer centre The current ATM based campus backbone network was established by the Computer centre in 1999. An optimized topology for the backbone has been designed considering aspects such as reliability, scalability and cost effectiveness. The backbone interconnects all the buildings in the institute zone using 12-core composite fibre optic cable. At the core of the network is a dual ATM ring (622/155 Mbps) providing redundancy and connecting 3ATM backbone switches placed optimized locations. These switches provide connectivity to most of the buildings.

Remote buildings not covered are connected to the core ATM switches through small ATM switches over 155 Mbps links. The edge device at each of the buildings provides 155Mbps ATM uplink and twleve10/100 Mbps Ethernet downlink ports. These ports in turn provide connectivity to labs, servers and switches that provide 100 Mbps uplink and 10 Mbps downlink ports to desktops for faculty and research staffs. The backbone also provides dial up connectivity through a modem bank 32 lines accessed through a single number (hunting). This remote access server provides access to the campus Internet and intranet for the residents transparently. Thus the backbone has a scalable reaching all faculty, staff and administrative offices and laboratories.

For the installation mostly, the existing conduits have been used for installation of the fibre optic cable. The three points for the backbone are Computer Centre, Hydraulics Lab and RSIC. The ATM small switches are placed in R&AC, MES and administration building. The edge devices are placed in optimal locations in each one of the buildings, so that any next level switch can be reached within the UTP CATS cable. The network provides about 200 ports at the 100 Mbps (lab/server) level and currently about 2500 nodes are in the network. This network is being expanded to cater all student hostels in the campus. This provides connectivity to about 3500 individual rooms. To implement the campus network, 3 ATM (622 Mbps) backbone switches, 3 ATM (155 Mbps) small switches, 25 edge devices with ATM (155 Mbps) uplink, 80 Ethernet switches, 15 kilometers of fibre optic cable, 100 kilometers of UTP cable and necessary fibre and UTP components has been used.