TCP/IP Protocol Stack Implementation

Reference: https://cs144.stanford.edu

This repository implements a complete TCP/IP protocol stack in C++, providing a layered network architecture that follows the traditional TCP/IP model with clear separation of concerns between layers. Key components are:

• Transport Layer: TCP sender/receiver with reliable data transmission, flow control, and retransmission
• Network Layer: IP routing with longest-prefix matching and packet forwarding
• Data Link Layer: Ethernet framing with ARP resolution for MAC address mapping
• Data Management: Efficient stream processing with circular buffering and reference management 1

Architecture

Layered Design

The system implements a complete TCP/IP protocol stack with clear layer separation:

Key Components

Component	Purpose	Key Files
ByteStream	Circular buffer for efficient data streaming	src/byte_stream.hh
TCPSender	Reliable data transmission with retransmission	src/tcp_sender.hh, src/tcp_sender.cc
TCPReceiver	Segment processing and acknowledgment generation	src/tcp_receiver.hh
Reassembler	Out-of-order segment reassembly	src/reassembler.hh
Router	Packet forwarding with routing table lookup	src/router.hh, src/router.cc
NetworkInterface	Ethernet framing and ARP resolution	src/network_interface.hh

Features

TCP Implementation

• Reliable Transmission: Sequence numbering, acknowledgments, and retransmission with exponential backoff
• Flow Control: Sliding window protocol with receiver window management
• Connection Management: SYN/FIN handshake handling and connection state tracking
• Error Handling: RST flag processing and error propagation 4

Network Layer

• IP Routing: Longest-prefix matching for route selection
• Packet Forwarding: TTL decrement and validation
• Multiple Interfaces: Support for multi-homed routing configurations

Data Link Layer

• ARP Protocol: Automatic IP-to-MAC address resolution with caching
• Ethernet Framing: Proper frame encapsulation and processing
• Timeout Management: ARP request expiration and mapping lifetime management 5

Configuration

The system uses configurable parameters for various protocol aspects: 6

• Buffer Capacity: Default 64KB for send/receive buffers
• Maximum Payload: 1000 bytes per TCP segment
• Retransmission Timeout: 1 second default with exponential backoff
• Maximum Retransmissions: 8 attempts before connection failure