Network Layer¶

Overview¶

The network layer provides high-performance, low-latency access to the Linux networking stack from raw Layer-2 frame injection to kernel-bypass DPDK drivers. All modules target sub-microsecond critical paths with zero dynamic allocation after initialization.

┌─────────────────────────────────────────────────────────────────────┐
│                        Application Layer                             │
├─────────────────────────────────────────────────────────────────────┤
│  raw_socket  │  epoll_reactor  │  zero_copy  │      dpdk           │
│  (AF_PACKET) │  (Event Loop)   │  (io_uring) │  (Userspace NIC)    │
├─────────────────────────────────────────────────────────────────────┤
│                     Linux Kernel / DPDK                              │
├─────────────────────────────────────────────────────────────────────┤
│                        NIC Hardware                                  │
└─────────────────────────────────────────────────────────────────────┘

Modules¶

Architecture¶

graph TD
    A[Application] --> B[epoll_reactor]
    B --> C[raw_socket]
    B --> D[zero_copy]
    C --> E[AF_PACKET / PACKET_MMAP]
    D --> F[io_uring / splice]
    E --> G[NIC]
    F --> G
    H[dpdk] --> G
    style H fill:#f9f,stroke:#333,stroke-width:2px
    style D fill:#f9f,stroke:#333,stroke-width:2px

Design Principles¶

1. Zero allocation after init All buffers pre-allocated at startup
2. Single-threaded ownership No locks in the hot path; use CPU pinning + SPSC queues for cross-core transfer
3. Batch processing Drain all ready events per syscall to amortize kernel transitions
4. Cache-line awareness Data structures aligned to prevent false sharing
5. Kernel bypass where possible PACKET_MMAP for Layer-2, DPDK for full bypass

Build¶

# Build all network modules
make -C src/network/raw_socket
make -C src/network/epoll_reactor

# Run with required capabilities
sudo setcap cap_net_raw+ep ./build/raw_socket_demo
./build/raw_socket_demo

Dependencies¶