CAMPUS NETWORKING: Gung ho about Gigabit

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