\documentclass[12pt, a4paper]{report} % --- PACKAGES --- \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage{mathptmx} % Standard Times New Roman font \usepackage{helvet} % Helvetica for headers \usepackage{courier} % Courier for code \usepackage[a4paper, top=3cm, bottom=3cm, left=3.5cm, right=2.5cm]{geometry} % Generous margins \usepackage{graphicx} % For images \usepackage{fancyhdr} % For headers/footers \usepackage{setspace} % For controlling line spacing \usepackage{titlesec} % For custom chapter titles \usepackage{listings} % For code/command formatting \usepackage{xcolor} % For colors \usepackage{hyperref} % For clickable links \usepackage{longtable} % For long tables \usepackage{array} % For better tables \usepackage{caption} % For caption formatting % --- DOCUMENT CONFIGURATION --- % DOUBLE SPACING to meet the page count requirement and provide a "lengthy" feel \doublespacing % Hyperlink Setup \hypersetup{ colorlinks=true, linkcolor=black, filecolor=black, urlcolor=blue, pdftitle={BSNL Industrial Training Report}, pdfauthor={Student Name} } % Chapter Title Formatting \titleformat{\chapter}[display] {\normalfont\huge\bfseries\centering}{\chaptertitlename\ \thechapter}{20pt}{\Huge} % Header and Footer \pagestyle{fancy} \fancyhf{} \lhead{\footnotesize BSNL Industrial Training} \rhead{\footnotesize Computer Science Dept.} \cfoot{\thepage} \begin{document} %---------------------------------------------------------------------------------------- % TITLE PAGE %---------------------------------------------------------------------------------------- \begin{titlepage} \begin{center} \vspace*{1cm} \Huge \textbf{INDUSTRIAL TRAINING REPORT} \vspace{0.5cm} \LARGE \textbf{STUDY OF MPLS CORE CONNECTIVITY AND BROADBAND NETWORK ARCHITECTURE AT BSNL} \vspace{1.5cm} \textit{Submitted in partial fulfillment of the requirements for the degree of} \\ \vspace{0.5cm} \textbf{Bachelor of Technology (B.Tech)} \\ \textit{in} \\ \textbf{Computer Science \& Engineering} \vspace{1.5cm} % Logo Placeholder \begin{figure}[h] \centering \framebox{\parbox{0.4\textwidth}{\centering \vspace{1cm} \textbf{BSNL LOGO} \\ \small\textit{(Insert Logo Here)} \vspace{1cm} }} \end{figure} \vspace{1.5cm} \begin{minipage}{0.45\textwidth} \begin{flushleft} \large \textbf{Submitted To:}\\ Bharat Sanchar Nigam Limited\\ Office of the General Manager\\ Telecom District, Meerut \end{flushleft} \end{minipage} \hfill \begin{minipage}{0.45\textwidth} \begin{flushright} \large \textbf{Submitted By:}\\ {[Student Name]}\\ {[Roll No]}\\ {[University Name]} \end{flushright} \end{minipage} \vfill \Large \textbf{Training Duration:} [Start Date] -- [End Date] \end{center} \end{titlepage} %---------------------------------------------------------------------------------------- % DECLARATION %---------------------------------------------------------------------------------------- \chapter*{Declaration} \addcontentsline{toc}{chapter}{Declaration} I hereby declare that the work presented in this Industrial Training Report, titled \textbf{"Study of MPLS Core Connectivity and Broadband Network Architecture at BSNL"}, is an original work carried out by me during my training at Bharat Sanchar Nigam Limited (BSNL), Meerut. This report has been prepared in accordance with the curriculum requirements of the Bachelor of Technology program in Computer Science. This work has not been submitted to any other institute or university for the award of any degree or diploma. The content presented here is based on my personal observations, the technical documentation provided by the training coordinators, and the practical exposure gained during the training period. \vspace{2cm} \noindent \textbf{Date:} \today \\ \textbf{Place:} Meerut \hfill \textbf{[Student Name]} \newpage %---------------------------------------------------------------------------------------- % ACKNOWLEDGEMENT %---------------------------------------------------------------------------------------- \chapter*{Acknowledgement} \addcontentsline{toc}{chapter}{Acknowledgement} I would like to express my sincere gratitude to \textbf{Bharat Sanchar Nigam Limited (BSNL)}, Meerut, for providing me the opportunity to undergo this Industrial Training in the Broadband and Switching Section of the National Internet Backbone (NIB). This training has been a valuable learning experience, offering practical exposure to real-time telecom network operations, broadband infrastructure, and switching systems. The hands-on experience gained during this period has significantly enhanced my understanding of theoretical concepts related to broadband technologies, IP/MPLS networks, aggregation, and access networks. I extend my heartfelt thanks to the training coordinator \textbf{Mr. Lalit (SDE)} and other officials at the NIB Switching Room, Meerut, for their continuous guidance, support, and cooperation throughout the training period. Their willingness to share knowledge, explain technical details, and provide insights into live network operations made this training highly informative and meaningful. I am also grateful to \textbf{Mr. Krishna Murari (DE Tx BSNL Meerut)} for granting permission and facilitating a conducive learning environment. Their professional approach and technical expertise greatly contributed to the successful completion of this industrial training. \newpage %---------------------------------------------------------------------------------------- % ABSTRACT %---------------------------------------------------------------------------------------- \chapter*{Abstract} \addcontentsline{toc}{chapter}{Abstract} This report presents a comprehensive account of the Industrial Training undertaken at Bharat Sanchar Nigam Limited (BSNL), Meerut, with a specific focus on the Computer Science aspects of the National Internet Backbone (NIB). The objective of the training was to bridge the gap between academic theory regarding computer networks and the practical reality of massive ISP infrastructure. During the training period, detailed insights were gained into the architecture and functioning of the backbone networks. The report details the transition from legacy circuit-based systems to modern Packet Switching networks utilizing **Multiprotocol Label Switching (MPLS)**. We explore the logical hierarchy of the network, including the Core (Tier-1), Aggregation (Tier-2), and Access (Tier-3) layers. Emphasis is laid on understanding technologies such as Fiber to the Home (FTTH), Gigabit Passive Optical Networks (GPON), and the role of the Broadband Network Gateway (BNG) in user authentication and traffic management. The report also covers the recent upgrades to the network, including the implementation of Control and User Plane Separation (CUPS) architecture. Finally, the report discusses the protocols that bind these systems together, including TCP/IP, OSPF for internal routing, and BGP for external connectivity. This document serves as a detailed record of the operational logic behind one of India's largest internet networks. \newpage %---------------------------------------------------------------------------------------- % TABLE OF CONTENTS %---------------------------------------------------------------------------------------- \tableofcontents \listoffigures \newpage %---------------------------------------------------------------------------------------- % CHAPTER 1 %---------------------------------------------------------------------------------------- \chapter{Introduction to BSNL and Telecommunications} \section{Overview of BSNL} Bharat Sanchar Nigam Limited (commonly known as BSNL) is an Indian central public sector undertaking under the ownership of the Department of Telecommunications. Established on 1st October 2000, it is the largest government-owned wireless telecommunications service provider in India. BSNL provides a vast array of services including mobile voice, internet services, and enterprise data solutions through its nationwide telecommunications network. BSNL holds a unique position in the Indian market as the fourth-largest ISP, with a presence that spans the entire country, including remote rural areas where private players often do not operate. It possesses the largest optical fiber network in the country, spanning approximately 7.5 lakh kilometers. \section{Historical Evolution of Services} The history of BSNL reflects the history of communication in India. \begin{itemize} \item **Landline:** BSNL was the sole provider of fixed-line services until the New Telecom Policy of 1999. It remains the market leader in wireline services. \item **Mobile:** BSNL Mobile offers GSM services under the brand "CellOne." It has over 121 million customers. Recently, BSNL has started rolling out indigenous 4G services and is preparing for 5G deployment using the 700 MHz and 2100 MHz bands. \item **Broadband:** BSNL launched broadband services (DataOne) in 2005. Today, it leads the market with "Bharat Fiber" (FTTH), offering speeds up to 300 Mbps. \end{itemize} \section{The Digital Shift: A CS Perspective} From a Computer Science perspective, the telecommunications industry has undergone a massive paradigm shift. In the past, telecom was about "Circuit Switching"—physically connecting two wires to create a voice circuit. Today, telecom is entirely about "Packet Switching." Voice, video, and text are all converted into digital IP packets. The modern telecom exchange is no longer filled with mechanical switches but is essentially a massive server room filled with routers and computers. This convergence means that a telecom engineer and a computer science engineer now work on the same fundamental technologies: Data Structures, Algorithms, and Protocols. \newpage %---------------------------------------------------------------------------------------- % CHAPTER 2 %---------------------------------------------------------------------------------------- \chapter{Network Architecture Fundamentals} \section{The Layered Approach} To understand how BSNL manages millions of connections, one must look at the network architecture. BSNL follows a hierarchical model that aligns with standard Computer Science networking principles. \subsection{The OSI Model Context} The entire network operation can be mapped to the OSI (Open Systems Interconnection) model: \begin{itemize} \item **Physical Layer (Layer 1):** The Fiber Optic cables and Copper wires. \item **Data Link Layer (Layer 2):** The Switches, VLANs, and GPON protocols. \item **Network Layer (Layer 3):** The Routers, IP Addressing, and MPLS pathfinding. \item **Application Layer (Layer 7):** The actual services like DNS, Web Browsing, and VoIP. \end{itemize} \section{Broadband Network Architecture Layers} The BSNL broadband network is logically divided into four distinct layers: \subsection{1. Core Network} This is the backbone. It is responsible for high-speed data transport, routing, and switching. It uses high-capacity routers (like Cisco 12416) and connects to the international internet gateways. It is designed for reliability and speed, not for connecting to users directly. \subsection{2. Aggregation Network} This layer sits between the Core and the Access layers. Its primary job is to "aggregate" or collect traffic from thousands of users and funnel it into the core. It uses large switches and Broadband Network Gateways (BNG) to enforce policies. \subsection{3. Access Network} This is the "Last Mile." It connects the service provider to the subscriber's home. Technologies used here include Fiber to the Home (FTTH) and Digital Subscriber Line (DSL). \subsection{4. Customer Premises Network} This is the equipment inside the user's home, such as the Modem (ONT) and the WiFi Router. \begin{figure}[h] \centering \framebox{\parbox{0.9\textwidth}{\centering \vspace{4cm} \textbf{Diagram Placeholder: General Network Architecture} \\ \small\textit{(Please insert the Layered Architecture diagram here)} \vspace{4cm} }} \caption{Logical Layers of the BSNL Network} \end{figure} \newpage %---------------------------------------------------------------------------------------- % CHAPTER 3 %---------------------------------------------------------------------------------------- \chapter{National Internet Backbone (NIB)} \section{Introduction to NIB} The National Internet Backbone (NIB) is the massive infrastructure project that enables internet connectivity across India. It was conceived to provide nationwide connectivity to ISPs and customers. \section{NIB-I (Phase 1)} The first phase, NIB-I, was designed primarily for dial-up access. It consisted of nodes at district headquarters connected via slower links. It utilized Remote Access Servers (RAS) to handle telephone dial-up connections. However, as the demand for broadband and multimedia grew, NIB-I became insufficient due to scalability issues. \section{NIB-II (Phase 2): The Current Backbone} BSNL launched NIB-II to create a high-speed, carrier-grade IP/MPLS network. This network is designed to support "Convergent Services"—integrating voice, data, and video onto a single platform. \subsection{Key Design Features of NIB-II} \begin{itemize} \item **High Availability:** The network uses a mesh topology, ensuring that if one path fails, traffic is automatically rerouted. \item **Scalability:** It can handle Terabits of data per second. \item **Service Diversity:** It supports VPNs, Managed Security, and Bandwidth-on-Demand. \end{itemize} \section{Hierarchical Node Layout} NIB-II classifies cities into a rigid hierarchy based on traffic volume and strategic importance. \subsection{Tier-1 Nodes (A1 Cities)} These are the "Super Core" nodes. There are five A1 cities in India: **New Delhi, Mumbai, Chennai, Kolkata, and Bangalore.** \begin{itemize} \item They connect to international gateways. \item They are fully meshed (connected to each other) using high-speed STM-16 and 10G optical links. \item **Hardware:** They use massive Core Routers like the **Cisco 12416 GSR** (Gigabit Switch Router). \end{itemize} \subsection{Tier-2 Nodes (A2 and A3 Cities)} These serve as regional hubs. \begin{itemize} \item **A2 Cities:** Hyderabad, Pune, Ahmedabad. \item **A3 Cities:** Lucknow, Jullunder, Jaipur, Indore, Ernakulam, Patna. \item These nodes connect to the A1 nodes. They use **Cisco 12410 GSR** routers. \end{itemize} \subsection{Tier-3 Nodes (A4 and B Cities)} These are the edge nodes, such as **Meerut**, Chandigarh, Guwahati, etc. They collect traffic from the city and send it to the nearest Core node. They typically use **Juniper M40e** or **Cisco 7613** routers. \begin{figure}[h] \centering \framebox{\parbox{0.9\textwidth}{\centering \vspace{5cm} \textbf{Diagram Placeholder: NIB-II Topology} \\ \small\textit{(Insert the map showing A1, A2, A3 cities connectivity)} \vspace{5cm} }} \caption{NIB-II Network Topology} \end{figure} \newpage %---------------------------------------------------------------------------------------- % CHAPTER 4 %---------------------------------------------------------------------------------------- \chapter{Multiprotocol Label Switching (MPLS)} \section{The Need for MPLS} In traditional IP routing (the method used by the basic internet), every router performs a complex lookup. When a packet arrives, the router looks at the Destination IP address, searches its massive routing table (which may have 800,000+ entries) to find the longest match, and then decides where to send it. From a Computer Science perspective, this is computationally expensive. It is an $O(\log n)$ or $O(n)$ operation depending on the data structure. Doing this at every hop introduces "Latency" (delay). **Multiprotocol Label Switching (MPLS)** was introduced to solve this. It combines the flexibility of IP routing with the speed of hardware switching. \section{How MPLS Works: The Label Concept} MPLS adds a small "Label" (a 32-bit header) to the data packet. \begin{itemize} \item **Ingress (Entry):** When a packet enters the BSNL network (e.g., at Meerut), the edge router analyzes the IP header once and assigns a Label (e.g., Label 105). \item **The Core:** The core routers (e.g., in Noida or Delhi) do *not* look at the IP address. They only look at the Label. They have a simple table: "If Label is 105, send to Port 2 and swap label to 200." \item **Egress (Exit):** The final router removes the label and delivers the IP packet. \end{itemize} This "Label Swapping" is an $O(1)$ operation—it is instant and handled by hardware chips (ASICs), not software. \section{Components of MPLS} \begin{enumerate} \item **LER (Label Edge Router):** Located at the edge. It pushes (adds) or pops (removes) labels. In BSNL, these are the routers connecting to the customers. \item **LSR (Label Switching Router):** Located in the core. They simply swap labels at high speed. \item **LSP (Label Switched Path):** The virtual path created across the network for the packets to travel. \end{enumerate} \section{MPLS VPNs} One of the most critical applications of MPLS in BSNL is **Layer 3 VPNs**. This allows BSNL to create private networks for banks and government offices over the public infrastructure. By using unique labels and Virtual Routing and Forwarding (VRF) instances, BSNL ensures that Bank A's traffic never mixes with Bank B's traffic, even though they use the same physical fiber cable. This is similar to the concept of Virtual Machines in computing—logically separate, but physically shared. \newpage %---------------------------------------------------------------------------------------- % CHAPTER 5 %---------------------------------------------------------------------------------------- \chapter{Access Technologies: FTTH and GPON} \section{The Last Mile Problem} The "Last Mile" refers to the connection between the ISP's exchange and the customer's home. This is the most expensive and complex part of the network. BSNL utilizes two main technologies here: DSL (Legacy) and FTTH (Modern). \section{Fiber to the Home (FTTH)} FTTH is the current gold standard. It replaces copper wires with Optical Fiber strands that carry data using light pulses (Photons) instead of electricity. This eliminates issues like signal attenuation and electromagnetic interference. \section{GPON Technology (Gigabit Passive Optical Network)} BSNL uses GPON standards (ITU-T G.984). The term "Passive" is crucial from an engineering standpoint. It means there are no electrically powered devices between the Exchange and the Customer. The signal is split using simple glass prisms. \subsection{GPON Architecture Components} \begin{enumerate} \item **OLT (Optical Line Terminal):** This is the main server located in the BSNL Exchange. It acts as the brain of the system, controlling traffic for thousands of users. It converts electrical signals from the core network into optical light signals. \item **Optical Splitter:** This is a passive device. It takes one fiber input and splits it into multiple outputs (usually 1:32 or 1:64). This allows BSNL to serve 32 customers with just a single fiber strand running from the exchange. \item **ONT (Optical Network Terminal):** This is the modem inside the user's home. It receives the light signal and converts it back into digital electrical signals (Ethernet) for the user's computer or WiFi router. \end{enumerate} \subsection{Transmission Logic} \begin{itemize} \item **Downstream (OLT to User):** Data is broadcast to all 32 users. The ONT filters the data and only accepts the packets meant for that specific user (using encryption). \item **Upstream (User to OLT):** Users send data using **Time Division Multiple Access (TDMA)**. Each user is assigned a specific microsecond time-slot to flash their laser. This prevents "Data Collisions" inside the fiber. \end{itemize} \begin{figure}[h] \centering \framebox{\parbox{0.9\textwidth}{\centering \vspace{4cm} \textbf{Diagram Placeholder: GPON Architecture} \\ \small\textit{(Insert GPON Diagram showing OLT -> Splitter -> ONT)} \vspace{4cm} }} \caption{GPON Network Diagram} \end{figure} \newpage %---------------------------------------------------------------------------------------- % CHAPTER 6 %---------------------------------------------------------------------------------------- \chapter{Broadband Network Gateway (BNG)} \section{Introduction to BNG} While routers move data, the **Broadband Network Gateway (BNG)** manages the *users*. It is the access point where subscribers connect to the broadband network. In older networks, this was called the BRAS (Broadband Remote Access Server). \section{Functions of the BNG} The BNG is a sophisticated computer that performs several critical logical functions: \subsection{1. Session Management} When a user turns on their router, it sends a request to the BNG. The BNG establishes a logical session (usually using PPPoE - Point to Point Protocol over Ethernet). \subsection{2. Authentication (AAA)} The BNG does not store passwords. When a user tries to connect, the BNG queries a central database called the **AAA Server** (Authentication, Authorization, and Accounting). It uses the **RADIUS** protocol for this. \begin{itemize} \item **Authentication:** Is this user valid? \item **Authorization:** What speed/plan did they pay for? \item **Accounting:** How much data have they used? \end{itemize} \subsection{3. IP Address Management} Once authenticated, the BNG assigns an IP address to the user. This is usually done via DHCP (Dynamic Host Configuration Protocol). \subsection{4. Quality of Service (QoS)} The BNG is responsible for enforcing speed limits. If a user pays for 100 Mbps, the BNG ensures they do not exceed this speed using "Traffic Shaping" algorithms. It also prioritizes Voice (VoIP) traffic over standard download traffic to ensure call quality. \section{The CUPS Architecture Upgrade} Recently, BSNL has upgraded its BNG infrastructure to **CUPS (Control and User Plane Separation)**. In traditional BNGs, the traffic processing (User Plane) and the decision logic (Control Plane) were in the same box. If traffic increased, the CPU would get overwhelmed. In CUPS: \begin{itemize} \item **Control Plane (CP):** Handles authentication and logic. It is centralized. \item **User Plane (UP):** Handles the raw traffic forwarding. It is distributed closer to the users. \end{itemize} This allows BSNL to scale the network massively by simply adding more User Plane nodes without changing the central logic. \newpage %---------------------------------------------------------------------------------------- % CHAPTER 7 %---------------------------------------------------------------------------------------- \chapter{Backend Systems and Protocols} \section{Aggregation Switches} Between the Access Layer (OLT) and the BNG lies the Aggregation Switch. These are Layer-2 and Layer-3 switches that combine traffic from multiple OLTs. \begin{itemize} \item **VLANs (Virtual Local Area Networks):** BSNL uses VLANs to separate traffic. For example, Internet data might be on VLAN 100, while IPTV data is on VLAN 200. This ensures that a high load on the internet does not freeze the TV. \item **Q-in-Q Tunneling:** BSNL uses a technique called "Q-in-Q" where the customer's VLAN tag is encapsulated inside a Service Provider VLAN tag. This allows BSNL to uniquely identify millions of customers even though the standard VLAN ID limit is only 4096. \end{itemize} \section{DWDM (Dense Wavelength Division Multiplexing)} For the core fiber optic cables connecting cities, BSNL uses DWDM. \begin{itemize} \item **Concept:** A single fiber strand usually carries one light signal. With DWDM, BSNL transmits multiple "colors" (wavelengths) of light down the same fiber simultaneously. \item **Capacity:** This allows a single fiber to carry 40 or 80 different channels, each running at 10 Gbps or 100 Gbps. This turns a standard cable into a massive data highway without digging up the ground to lay new cables. \end{itemize} \newpage %---------------------------------------------------------------------------------------- % CHAPTER 8 %---------------------------------------------------------------------------------------- \chapter{Experimental Analysis: Network Diagnostics} \section{Objective} To apply Computer Science networking concepts to observe the path of data packets through the BSNL network hierarchy using command-line diagnostic tools. \section{Tool Used: Traceroute} The `tracert` (Windows) or `traceroute` (Linux) command allows us to see the "Hops" a packet takes to reach a destination. It works by manipulating the TTL (Time To Live) field in the IP header. \section{Procedure} 1. Connect a workstation to the BSNL FTTH network. 2. Open the Command Terminal. 3. Execute: \texttt{tracert www.google.com} 4. Analyze the IP addresses returned. \section{Observation and Analysis} The output typically shows a distinct pattern that matches the hierarchy discussed in this report: \begin{itemize} \item **Hop 1 (Local):** The User's Router (Gateway). Latency < 1ms. \item **Hop 2 (Access):** The BSNL Aggregation Switch or BNG in Meerut. \item **Hop 3 (Core):** A Tier-2 Node (likely Noida or Delhi). The latency increases to approx 15-20ms. \item **Hop 4 (Super Core):** An NIB-II MPLS Router. The IP address often has reverse DNS entries indicating "MPLS" or "Backbone." \item **Hop 5+ (External):** The packet leaves BSNL and enters the global internet (e.g., Google's network). \end{itemize} \section{Conclusion of Experiment} This experiment confirms the theoretical hierarchical model. We can physically see the latency introduced by the distance to the Core routers, confirming that internet traffic from Meerut is backhauled to a major hub before going to the internet. \newpage %---------------------------------------------------------------------------------------- % CHAPTER 9 %---------------------------------------------------------------------------------------- \chapter{Conclusion and Future Scope} \section{Conclusion} The Industrial Training at BSNL Meerut provided a profound insight into the practical implementation of Computer Science concepts. While the university curriculum focuses on the theory of algorithms and small-scale LANs, BSNL demonstrates how these concepts scale to support a nation of 1.4 billion people. We observed that the network is not just a collection of cables, but a highly intelligent, software-driven system. The migration to IP/MPLS has transformed BSNL from a telephone operator to a digital data carrier. The implementation of FTTH and GPON has solved the bottleneck of the "last mile," bringing Gigabit speeds to homes. \section{Future Scope} The telecom sector is rapidly evolving. The next steps for BSNL include: \begin{itemize} \item **5G Deployment:** The fiber infrastructure laid for FTTH will serve as the backhaul for 5G towers. \item **IPv6 Migration:** With the exhaustion of IPv4 addresses, the entire NIB is moving toward dual-stack IPv6 implementation. \item **SDN (Software Defined Networking):** Moving the control logic from routers to centralized servers, making the network programmable. \end{itemize} This training has bridged the gap between the classroom and the industry, providing a solid foundation for a career in Network Engineering and System Architecture. \newpage %---------------------------------------------------------------------------------------- % BIBLIOGRAPHY %---------------------------------------------------------------------------------------- \begin{thebibliography}{9} \bibitem{bsnl_doc} BSNL Internal Training Documents, "Overview of NIB-II and Broadband Architecture," BSNL Meerut, 2026. \bibitem{tanenbaum} Andrew S. Tanenbaum, "Computer Networks," 5th Edition, Pearson Education. \bibitem{rfc3031} IETF RFC 3031, "Multiprotocol Label Switching Architecture." \bibitem{gpon_standard} ITU-T Recommendation G.984, "Gigabit-capable Passive Optical Networks (GPON)." \bibitem{cisco_mpls} Cisco Systems, "MPLS Fundamentals and Configuration Guide." \end{thebibliography} \end{document}