Learning P4

IP/MAC Header

• MAC Layer - Ethernet Type II Frame, which contain:

  • MAC Header: (14 bytes)
    • Destination MAC Address: 6 bytes
    • Source MAC Address: 6 bytes
    • EtherType: 2 bytes 這也是為什麼在範例中，使用的 ethernet_t 中使用的是 ( 48 + 48 + 16 ) bits 的格式（e.g. = MAC Header）
  • Data: (46~1500 bytes)
    • Payload(IP, ARP, etc.)
  • CRC Checksum: 4 bytes

• IP Header

  • ip version: 4 bits
  • hdr lens: 4 bits
  • TOS (Type of Service): 8 bits
  • Total Length: 16 bits
  • identification (Fragment ID): 16 bits
  • flags (R, DF, MF): 3 bits
  • fragment offset: 13 bits
  • TTL (Time-To-Live): 8 bits
  • Protocol: 8 bits
  • Header Checksum: 16 bits
  • Source IP Address: 32 bits
  • Destination ID Address: 32 bits ( P4 tutorial 擷取到這部份 )
  • Options: 32 bits
  • Data: leftover part (from 24 bytes ~ end)

• TCP Header

Introduction to router/switch architecture

• Awesome work:

  • Part 1 - Router Architecture
  • Part 2 - Packet forwarding by IP Router
  • Part 3 - L2 (Ethernet) Switching by L3 Switch
  • Part 4 - IP Forwarding by L3 Switch

• 透過硬體架構上的了解，以及其實作的機制，來輔助解釋 switching/routing 的過程！非常的棒！

Part 1

Part 2

Part 3

Part 4

IP, ethernet switching mechanism

• Awesome work on illustration about IP, ethernet switching process, website here:

  • Ethernet switching
  • IP routing

• 圖解過程，並且一步步的帶著讀者了解過程！