medium10 marks

Computer Networks

Layering concepts, OSI and TCP/IP stacks, packet/circuit/virtual circuit switching, data link layer (framing, error detection, MAC, Ethernet bridging), routing protocols (shortest path, flooding, distance vector, link state), IP addressing, fragmentation, IPv4, CIDR, ARP/DHCP/ICMP, NAT, transport layer (flow control, congestion control, UDP, TCP, sockets), application layer (DNS, SMTP, HTTP, FTP, email).

27 Topics

40h prep

13.89% subject weight

27 Topics

Concept of layering

Protocol layering: each layer provides services to layer above.

1/10

📌 Key FormulaEncapsulation: data + headers.

OSI and TCP/IP Protocol Stacks

OSI: 7 layers (physical, data link, network, transport, session, presentation, application). TCP/IP: 4 layers (network interface, internet, transport, application).

1m1/10

📌 Key FormulaMapping between OSI and TCP/IP.

Basics of packet

Packet switching: data divided into packets, store-and-forward.

1/10

📌 Key FormulaTransmission delay = packet size / bandwidth.

Circuit and virtual circuitswitching

Circuit switching (dedicated path), virtual circuit (pre-established route).

1/10

📌 Key FormulaVirtual circuit uses VC identifier.

Data link layer

Framing, error detection, flow control, media access control.

1m2/10

📌 Key FormulaCRC, checksum.

Framing

Byte stuffing, bit stuffing, length field.

2/10

📌 Key FormulaFlag bytes with stuffing.

Error detection

Parity, checksum, CRC (cyclic redundancy check).

1m2/10

📌 Key FormulaCRC polynomial division.

Medium Access Control

Multiple access protocols: ALOHA, CSMA, CSMA/CD (Ethernet), CSMA/CA (Wi-Fi).

1m2/10

📌 Key FormulaThroughput of ALOHA: S = G e^{-2G} (pure), S = G e^{-G} (slotted).

Ethernet bridging

Bridges connect LAN segments using MAC addresses. Spanning tree protocol (STP).

2/10

📌 Key FormulaForwarding table learning.

Routing protocols

Algorithms for best path: RIP (distance vector), OSPF (link state), BGP (path vector).

1m3/10

📌 Key FormulaBellman-Ford equation for distance vector.

Shortest path

Dijkstra's algorithm, Bellman-Ford, used in routing.

1m3/10

📌 Key FormulaDijkstra runs on link state advertisements.

Flooding

Forward every incoming packet to all ports (except where arrived). Used for broadcasting.

1/10

📌 Key FormulaHop count limit.

Distance vector and link state routing

DV: share entire routing table with neighbors (RIP). LS: share link state info with all routers (OSPF).

1m2/10

📌 Key FormulaDV: Rx = min(cost + neighbor's distance).

Fragmentation and IP addressing

IPv4 address classes, subnetting, CIDR, fragmentation of IP packets at routers.

1m2/10

📌 Key FormulaMTU, fragment offset (multiple of 8 bytes).

IPv4

32-bit addresses, dotted decimal. Header format (version, IHL, TOS, total length, TTL, protocol, checksum, source/dest IP).

1m2/10

📌 Key FormulaTotal length = header + data (max 65535).

CIDR notation

Classless Inter-Domain Routing: address/mask (e.g., 192.168.1.0/24).

1m2/10

📌 Key FormulaNumber of addresses = 2^{32-mask}.

Basics of IP support protocols (ARP/ DHCP/ICMP)

ARP: IP to MAC address mapping. DHCP: dynamic IP assignment. ICMP: error reporting and ping.

1m2/10

📌 Key FormulaARP cache, DHCPDISCOVER, ICMP echo request/reply.

Network Address Translation (NAT)

Mapping private IPs to public IP, using port numbers.

2/10

📌 Key FormulaPort Address Translation (PAT).

Transport layer flow control and congestion control

Flow control (sliding window, TCP window), congestion control (AIMD, slow start, congestion avoidance, fast retransmit/recovery).

1m3/10

📌 Key FormulaCWND, threshold, additive increase multiplicative decrease.

Transport layer UDP

Connectionless, unreliable, no flow/congestion control. Header: source port, dest port, length, checksum.

1m1/10

📌 Key FormulaChecksum optional (set to 0).

Transport layer TCP

Connection-oriented, reliable, in-order, flow/congestion control, full-duplex. Header: sequence number, ACK number, flags (SYN, ACK, FIN, RST), window size, checksum, urgent pointer.

1m3/10

📌 Key Formula3-way handshake: SYN, SYN-ACK, ACK.

Transport layer sockets

Endpoint for communication: IP address + port number.

1/10

📌 Key FormulaSocket API: socket(), bind(), listen(), accept(), connect(), send(), recv().

Application layer protocols DNS

Domain Name System: translates domain names to IP addresses.

1m2/10

📌 Key FormulaHierarchical: root, TLD, authoritative. Recursive vs iterative queries.

Application layer protocols SMTP

Simple Mail Transfer Protocol for email delivery.

1m1/10

📌 Key FormulaCommands: HELO, MAIL FROM, RCPT TO, DATA, QUIT.

Application layer protocols HTTP

Hypertext Transfer Protocol: request/response, methods (GET, POST, PUT, DELETE), status codes, headers.

1m2/10

📌 Key FormulaPersistent vs non-persistent connections.

Application layer protocols FTP

File Transfer Protocol: uses two channels (control port 21, data port 20).

1/10

📌 Key FormulaActive vs passive mode.

Application layer protocols Email

Email architecture: MUA, MTA, MDA. Protocols: SMTP, POP3, IMAP.

1/10

📌 Key FormulaPOP3: download and delete. IMAP: keep on server.

medium10 marks

Computer Networks

27 Topics

40h prep

13.89% subject weight

27 Topics

Concept of layering

Protocol layering: each layer provides services to layer above.

1/10

📌 Key FormulaEncapsulation: data + headers.

OSI and TCP/IP Protocol Stacks

OSI: 7 layers (physical, data link, network, transport, session, presentation, application). TCP/IP: 4 layers (network interface, internet, transport, application).

1m1/10

📌 Key FormulaMapping between OSI and TCP/IP.

Basics of packet

Packet switching: data divided into packets, store-and-forward.

1/10

📌 Key FormulaTransmission delay = packet size / bandwidth.

Circuit and virtual circuitswitching

Circuit switching (dedicated path), virtual circuit (pre-established route).

1/10

📌 Key FormulaVirtual circuit uses VC identifier.

Data link layer

Framing, error detection, flow control, media access control.

1m2/10

📌 Key FormulaCRC, checksum.

Framing

Byte stuffing, bit stuffing, length field.

2/10

📌 Key FormulaFlag bytes with stuffing.

Error detection

Parity, checksum, CRC (cyclic redundancy check).

1m2/10

📌 Key FormulaCRC polynomial division.

Medium Access Control

Multiple access protocols: ALOHA, CSMA, CSMA/CD (Ethernet), CSMA/CA (Wi-Fi).

1m2/10

📌 Key FormulaThroughput of ALOHA: S = G e^{-2G} (pure), S = G e^{-G} (slotted).

Ethernet bridging

Bridges connect LAN segments using MAC addresses. Spanning tree protocol (STP).

2/10

📌 Key FormulaForwarding table learning.

Routing protocols

Algorithms for best path: RIP (distance vector), OSPF (link state), BGP (path vector).

1m3/10

📌 Key FormulaBellman-Ford equation for distance vector.

Shortest path

Dijkstra's algorithm, Bellman-Ford, used in routing.

1m3/10

📌 Key FormulaDijkstra runs on link state advertisements.

Flooding

Forward every incoming packet to all ports (except where arrived). Used for broadcasting.

1/10

📌 Key FormulaHop count limit.

Distance vector and link state routing

DV: share entire routing table with neighbors (RIP). LS: share link state info with all routers (OSPF).

1m2/10

📌 Key FormulaDV: Rx = min(cost + neighbor's distance).

Fragmentation and IP addressing

IPv4 address classes, subnetting, CIDR, fragmentation of IP packets at routers.

1m2/10

📌 Key FormulaMTU, fragment offset (multiple of 8 bytes).

IPv4

32-bit addresses, dotted decimal. Header format (version, IHL, TOS, total length, TTL, protocol, checksum, source/dest IP).

1m2/10

📌 Key FormulaTotal length = header + data (max 65535).

CIDR notation

Classless Inter-Domain Routing: address/mask (e.g., 192.168.1.0/24).

1m2/10

📌 Key FormulaNumber of addresses = 2^{32-mask}.

Basics of IP support protocols (ARP/ DHCP/ICMP)

ARP: IP to MAC address mapping. DHCP: dynamic IP assignment. ICMP: error reporting and ping.

1m2/10

📌 Key FormulaARP cache, DHCPDISCOVER, ICMP echo request/reply.

Network Address Translation (NAT)

Mapping private IPs to public IP, using port numbers.

2/10

📌 Key FormulaPort Address Translation (PAT).

Transport layer flow control and congestion control

Flow control (sliding window, TCP window), congestion control (AIMD, slow start, congestion avoidance, fast retransmit/recovery).

1m3/10

📌 Key FormulaCWND, threshold, additive increase multiplicative decrease.

Transport layer UDP

Connectionless, unreliable, no flow/congestion control. Header: source port, dest port, length, checksum.

1m1/10

📌 Key FormulaChecksum optional (set to 0).

Transport layer TCP

Connection-oriented, reliable, in-order, flow/congestion control, full-duplex. Header: sequence number, ACK number, flags (SYN, ACK, FIN, RST), window size, checksum, urgent pointer.

1m3/10

📌 Key Formula3-way handshake: SYN, SYN-ACK, ACK.

Transport layer sockets

Endpoint for communication: IP address + port number.

1/10

📌 Key FormulaSocket API: socket(), bind(), listen(), accept(), connect(), send(), recv().

Application layer protocols DNS

Domain Name System: translates domain names to IP addresses.

1m2/10

📌 Key FormulaHierarchical: root, TLD, authoritative. Recursive vs iterative queries.

Application layer protocols SMTP

Simple Mail Transfer Protocol for email delivery.

1m1/10

📌 Key FormulaCommands: HELO, MAIL FROM, RCPT TO, DATA, QUIT.

Application layer protocols HTTP

Hypertext Transfer Protocol: request/response, methods (GET, POST, PUT, DELETE), status codes, headers.

1m2/10

📌 Key FormulaPersistent vs non-persistent connections.

Application layer protocols FTP

File Transfer Protocol: uses two channels (control port 21, data port 20).

1/10

📌 Key FormulaActive vs passive mode.

Application layer protocols Email

Email architecture: MUA, MTA, MDA. Protocols: SMTP, POP3, IMAP.

1/10

📌 Key FormulaPOP3: download and delete. IMAP: keep on server.