LAN Trainer

The Benchmark LAN-T - LAN Trainer - is a versatile laboratory system that supplements courses on computer networks and LANs. Developed by Benchmark Electronic Systems in collaboration with IIT-Madras, the LAN-T exposes users to networking concepts at the physical, MAC, network and transport layers through a carefully designed series of experiments.

The LAN-T is a hardware and software based product. Emulation of nodes, topologies, etc., are implemented in a combination of hardware, firmware and software to emulate a real network environment. All the network layers can be implemented in the software. This arrangement gives more freedom to try out various protocols and layers, in the network, and study their behaviour.

Training in Networks The Benchmark LAN-T is ideal as:
  • A single trainer solution for training in various types of networks
  • An instrument for structuring training courses in networking
  • For facilitating development projects in networks
The LAN-T is particularly suited for:
  • Students at B.Tech/B.S. & M.S. levels in engineering/technical institutes (CS & EE)
  • Technical training centres in network organisations
  • R&D personnel and practicing engineers in research labs and industry
The LAN-T delivers:
  • In-depth exposure to networking concepts
  • Experimentation through programming in several protocols and network layers

The Benchmark LAN-T has been designed so that its experiments reinforce the theory covered in lectures, while hands-on programming exercises train users to fit into networking positions in industry. Moreover, the Trainer can also be used for projects involving many layers of networking hierarchy.

In short, the Benchmark LAN-T's versatility, expandability and cost-effectiveness makes it the perfect solution for all LAN trainer needs. The following will help to illustrate the reasons why...

Wide functionality at a low cost

With just a minimal investment in a single trainer and 2-3 PCs, users can obtain hands-on experience with a wide variety of different network topologies and protocols, including all the popular ones such as CSMA/CD (Ethernet) and token passing (Arcnet, Token Ring).

The trainer features include:
  • User configurable data rates
  • Generation of bit errors and frame errors between nodes
  • Variable network size
  • User configurable delays between nodes
  • ALOHA, CSMA, CSMA/CD, Token Bus, Token Ring, Star, Stop-and-Wait and various window protocols for reliable data transfer
Scalable and configurable

The Benchmark LAN-T's NEU emulates 6 nodes, which can be configured to Bus, Star or Ring topologies. It also has error generators and delay generators between nodes. Each NIU card emulates 2 independent nodes supporting various MAC layers, on a single PC. The system scales up to emulate larger networks by adding on more NEUs, NIUs and PCs.

The Benchmark LAN-T LAN Trainer consists of a Network Emulator Unit (NEU) with PC plug-in Network Interface Units (NIU) and Windows 98SE and/or Windows 2000 based experiment software. The software contains a series of experiments in the form of stand-alone applications, 'C' source code for the experiments, and a 'C' library to access the NIU. The source code provides better understanding of the experiments, while the library allows users to program new experiments, modify existing experiments, and try out various network layers and protocols.

In short, the Benchmark LAN-T's versatility, expandability and cost-effectiveness makes it the perfect solution for all Local Area Network (LAN) training needs.

Comprehensive set of experiments to observe and measure the behaviour of several LAN protocols:

1.MAC Layer: ALOHA, CSMA, CSMA/CD, CSMA/CA, Token Bus, Token Ring, Star

2.Data Link Layers: Stop-and-Wait, Sliding Window – Go-Back-N and Sliding Window – Selective-Repeat

  • User configurable data rates – 8, 16, 32, 64,128, 256, 512 Kbps, 1Mbps
  • Generation of Bit errors and Frame errors between nodes – up to 10-6
  • Variable network size – upto six nodes with each NEU. NEUs can be cascaded to increase the network size
  • Emulation of two nodes by each PC . Halves the number of PCs required
  • User configurable delays between nodes – emulates the propagation delay in real networks
  • Allows experimentation using the software provided; source code included for better understanding. Allows programming all experiments from scratch using the library, for more in-depth exposure
  • Menu driven user interface to experiments
  • Comprehensive manual – suitable for both lab instruction as well as self-study, requiring minimal involvement on the part of the lab staff

Observation and measurement of behaviour of various network protocols. Step-by-Step instructions given in manual under "Trying it out" section.

Packet transmission – packetization of data, simple point-to-point communication MAC Layer – Observe and measure the performance of various MAC Layer protocols by changing the network load, distance between the nodes wherever applicable and compare them: BUS Topology:
  • ALOHA: Exposure to multiple access to a shared medium, throughput vs offered load
  • CSMA: Throughput vs offered load for various node distances in the form of bit delays
  • CSMA/CD: Throughput vs offered load, packet delay vs throughput at various loads
  • Token-Passing BUS: Demand assignment when compared to random access protocols, packet delay vs throughput – comparison with CSMA/CD
  • CSMA/CA: DCF mode operation – Throughput vs offered load – comparison with CSMA/CD performance
RING Topology:
  • Token Ring: Throuhgput vs average packet delay at various loads and timeout values, performance comparison with CSMA/CD
DLL: Observe and measure the performance of various DLL protocols by changing the network load, various timeout period, introducing bit errors and compare them
  • Stop-and-Wait: Throughput vs BER for different packet lengths and timeout values
  • Sliding Window – Go-Back-N: Pipelining concept – throughput vs BER for different packet lengths and timeout values – comparison with Stop-and-Wait
  • Sliding Window – Selective-Repeat: Pipelining with selective re-transmissions concept – throughput vs BER for different packet lengths and timeout values – comparison with Go-Back-N
Network Layer: Study of Routing Protocols
  • Distance Vector routing: Hop-by-hop routing, routing table updation, count-to-infinity problem exposure
  • Link State routing: Routing table updation, effect of shortest path algorithm, comparison with DV routing
Application Layer:
  • File transfer using sockets: TCP connection establishment, session management
Serial/Parallel port networking: Simple network connectivity using serial and parallel ports in a PC, setup TCP/IP communication through PPP Data security in computer networks:
  • Data protection: RC4 symmetric stream cipher-key generation, encryption-decryption steps
  • Network threat: Sniffing of raw data and encrypted data in a LAN
STAR Topology (Optional):
  • ALOHA, CSMA, CSMA/CD, Stop & Wait and Sliding Window GBN protocols performance in STAR topology
  • Switching in LAN: Switching at Layer 2, self-learning using Baran's backward learning algorithm
Suggested Projects – The following projects can be undertaken with the user detailing the specification and implementation:
  • CSMA/CA – PCF mode
  • CSMA/CA – Ad-hoc network
  • Sliding Window – Jumping Window
  • Routing in a Mesh WAN
  • Network Management
  • Spoofing in a LAN
Experiment Software
LAN Trainer Shell
Provides a menu-driven interface
'C' library
Programming interface to the NIU
Stand-alone programs
For Level 1 experiments. Source code
provided for study and analysis
Saving of experiment results to a file
Display of experiment activities in the application window, wherever applicable
Network Emulator Unit (NEU)
Data rates
8, 16, 32, 64,128, 256, 512Kbps, 1Mbps
Bus, Ring, Star (optional)
0 to 15 bits between each pair of nodes
Error Generators (between one pair of nodes)
Bit Error – 0 to 10-6
Frame Error – 0 to 10-5
6 nodes per NEU (3 PCs can be connected per NEU. Each PC acts as 2 nodes)
Network Interface Unit (NIU)
PC plug-in card
32 bit, 33MHz PCI Bus (PCI ver 2.0 compliant)
MAC Layer support
ALOHA, CSMA, CSMA /CD, Token Bus, Token Ring
2 nodes per NIU
System Requirements
Pentium or higher
One PCI slot required
Operating System
Windows XP or Windows 2000
Number of PCs
2 to 3
Visual C++ compiler
V5.0 or above (Optional for programming / modifying
experiments as suggested in exercise and for further
Ordering Information
LAN-T Comprising
Network Emulator Unit (NEU)
Network Interface Unit (NIU)
Experiment software with libraries and source code Manuals
User manual –
Installation manual –
Programmer's manual –
Optional – Star Topology Comprising
Star dongle
Network Interface Unit
User Manual