#Ethernet
---
protocol: &ethframe
  name: eth-frame
  osilayer: 2
  fields:
    - 
      field: destination MAC
      length: 6
    - 
      field: source MAC
      length: 6
    -
      field: vlan tag
      length: 4
      subfields: 
        -
          field: tag protocol identifier (0x8100)
          length: 2
        -
          field: tag control information
          length: 2
          subfields:
            -
              field: priority code point (PCP)
              bitfield: yes
              length: 3
            -
              field: drop eligible indicator (DEI)
              bitfield: yes
              length: 1
            -
              field: VLAN identifier (VID)
              bitfield: yes
              length: 12
    -
      field: protocolid
      desc: Ethertype (Eth II) or length (IEEE 802.3)
      length: 2
      nextlayer: yes
    -
      field: data
      data: true
    -
      field: CRC
      desc: FCS (32-bit CRC)
      length: 4
      optional: yes #most network stacks compute that automatically