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18.1 Possible Changes to the IP Header

18.1 Possible Changes to the IP Header

The ECN field in the IP header has four possible codepoints: not-ECT (00), ECT(0) (10), ECT(1) (01), and CE (11). There are twelve possible transitions between these four values. However, we can classify these possible transitions into four main categories:

  • Erasing the Congestion Indication
  • Falsely Reporting Congestion
  • Disabling ECN-Capability
  • Falsely Indicating ECN-Capability

The following subsections discuss these categories in detail.