Computer Networks
CN Part-1
- What is a Computer Network?
- Goals and Applications of Computer Networking
- Computer Network Components
- Types of Computer Networks
- Network Topology
- Difference between Client Server and Peer to Peer Network
- Layered Architecture in Computer Networks
- Protocol Hierarchy in Computer Networks
- Interfaces and Services in Computer Networks
- Connection Oriented and Connectionless Services
- Service Primitives
- OSI Model
- TCP/IP Model
- Difference between OSI Model and TCP/IP Model
- Encapsulation and Decapsulation in Computer Networks
- Queueing Models in Computer Network
CN Part-2
- Physical Layer in Computer Networks
- Transmission Media in Computer Networks
- Analog and Digital Signals
- Data Rate and Bandwidth
- Encoding Techniques
- Multiplexing in Computer Networks
- Transmission Modes in Computer Networks
- Data Link Layer
- Framing in Data Link Layer
- Flow Control in Data Link Layer
- Error Control in Data Link Layer
- Error Detection and Correction in Computer Networks
- Stop and Wait Protocol
- Sliding Window Protocol
- SDLC(Synchronous Data Link Control) Protocol
- High-Level Data Link Control (HDLC) Protocol
- Point-to-Point Protocol (PPP)
CN Part-3
- MAC Sublayer and MAC Addressing
- Channel Allocation Methods
- ALOHA Protocol (Pure and Slotted ALOHA)
- CSMA/CD and CSMA/CA in Computer Networks
- Ethernet (IEEE 802.3)
- Wireless LANs (IEEE 802.11, Wi-Fi, and Bluetooth Basics)
- Network Layer and Design Issues
- IPv4 and IPv6 Protocols
- Addressing: IP Address, Subnetting, and Supernetting
- Routing Algorithms: Static vs Dynamic, Distance Vector, and Link State
- Routing Protocols: RIP, OSPF, and BGP
- Packet Switching and IP Fragmentation
- Network Layer Protocols: ICMP, ARP, RARP, DHCP, and NAT
CN Part-4
- Transport Layer and Functions
- Process-to-Process Delivery, Ports, and Sockets
- TCP Segment and Three-Way Handshake Connection Establishment
- UDP (User Datagram Protocol): Format and Features
- Flow Control and Error Control in Transport Layer
- Congestion Control: Leaky Bucket, Token Bucket, and TCP Congestion Control
CN Part-5
- Application Layer Architecture and Principles
- Domain Name System (DNS)
- Email Protocols: SMTP, POP3, and IMAP
- File and Web Protocols: FTP, HTTP, and HTTPS
- Remote Access Protocols: Telnet and SSH
- World Wide Web (WWW) and Web Architecture
- Network Security Basics: SSL, TLS, and Cryptography Fundamentals
Routing Protocols: RIP, OSPF, and BGP in Computer Networks
Routing Protocols kya hote hain?
Jab routers dynamically ek doosre ke saath routing information exchange karte hain aur automatically best paths discover karte hain, toh wo jin rules aur communication standards ko follow karte hain unhe Routing Protocols kehte hain.
Internet ko manage karne ke liye networks ko Autonomous Systems (AS) mein baanta gaya hai. Ek AS ek single administrative entity (jaise Airtel, Jio, ya Google) dwara manage hone wale routers ka group hota hai.
Routing protocols do categories mein divide hote hain:
- IGP (Interior Gateway Protocols): Ek hi AS ke andar use hone wale protocols (e.g. RIP, OSPF).
- EGP (Exterior Gateway Protocols): Alag-alag AS ke beech internet-scale routing ke liye use hone wale protocols (e.g. BGP).
1. RIP (Routing Information Protocol)
RIP sabse puraana Distance Vector IGP protocol hai jo Bellman-Ford algorithm par based hai.
Metric: RIP ka metric sirf Hop Count hota hai (packet kitne intermediate routers se hokar guzrega). Link speed ya bandwidth ko RIP ignore kar deta hai!
Max Hop Count: 15. Agar hop count 16 ho jaye, toh destination ko Unreachable (Infinity) declare kar diya jaata hai. Isliye RIP sirf chote networks (maximum 15 routers) ke liye suitable hai.
Update Mechanism: Har 30 seconds mein router apni complete routing table UDP port 520 par broadcast (RIPv1) ya multicast
224.0.0.9(RIPv2) karta hai.
2. OSPF (Open Shortest Path First)
OSPF modern enterprise networks ka sabse popular Link State IGP protocol hai jo IETF dwara open standard banaya gaya (RFC 2328).
Algorithm: Dijkstra’s Shortest Path First (SPF) algorithm use karta hai.
Metric: Cost. OSPF metric link bandwidth par calculate hoti hai:
Cost = Reference Bandwidth (100 Mbps) / Interface Bandwidth. Fast fiber links ko low cost milti hai, jisse OSPF hamesha high-speed path chunta hai.Hierarchical Areas: Badi enterprises mein OSPF network ko Areas mein divide karta hai:
- Backbone Area (Area 0): Core central area jisse baaki sabhi standard areas connect hote hain.
- ABR (Area Border Routers): Jo do areas ke beech traffic route karte hain.
Convergence: Bohot fast convergence. Update periodic nahi hota, sirf topology change hone par Triggered LSA (Link State Advertisements) multicast address
224.0.0.5aur224.0.0.6par flood karta hai.
3. BGP (Border Gateway Protocol)
BGP pure Global Internet ka routing protocol hai! Yeh ek Path Vector EGP (Exterior Gateway Protocol) hai jo alag-alag Autonomous Systems (ISPs, Telcos, Data Centers) ke beech traffic route karta hai.
Metric: BGP hop count ya link speed par nahi chalta, balki Routing Policies, AS-Path, aur Business Rules par chalta hai (Policy-based Routing).
AS-Path Attribute: Har route update mein list of AS numbers hoti hai jinse packet hokar guzrega (e.g., AS100 -> AS200 -> AS300). Agar router ko AS-Path mein apna hi AS number dikhta hai, toh wo loop detect karke packet reject kar deta hai (Loop-free routing).
Reliability: BGP reliable delivery ke liye TCP Port 179 par connection banata hai.
RIP vs OSPF vs BGP Comparison (Exam High-Yield!)
| Feature | RIP | OSPF | BGP |
|---|---|---|---|
| Protocol Type | Distance Vector (IGP) | Link State (IGP) | Path Vector (EGP) |
| Underlying Algorithm | Bellman-Ford | Dijkstra’s SPF | Best Path Selection (Policy based) |
| Routing Metric | Hop Count (Max 15) | Cost (Inversely proportional to Bandwidth) | Path Attributes (AS-Path, Weight, Local Pref) |
| Transport Layer Protocol | UDP Port 520 | Direct IP (Protocol 89) | TCP Port 179 |
| Convergence Speed | Slow | Very Fast | Slow to Moderate (huge internet table) |
| Network Scale | Small LANs / offices | Medium to large enterprise networks | Global Internet backbone |
Summary Table
| Routing Protocol | Summary Punchline |
|---|---|
| RIP | Hop-count based, simple, limited to 15 hops. |
| OSPF | Bandwidth-cost based, hierarchical Area 0 design, fast Dijkstra calculations. |
| BGP | The glue of the Internet. Inter-domain routing via TCP 179 and AS-Path policies. |