DSCP Diffserve code point

• Priority markings on IP traffic.
• How to match with tcpdump ?
  • for EF
    1. Take 101110 and shift it left two bits: 10111000 (ECN is right 2 bits)
    2. Convert it to hex: 0xb8
    3. Create a filter, masking out the ECN bits:

       • ip[1] & 0xfc == 0xb8

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