I know there are certain error detecting and correcting codes added at the Layer 2. However is it still possible to have errors go undetected eve with the addition of these codes?

What type of networks are more prone to undetected errors?

Are wireless networks more prone to undetected errors?

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    Feb 19, 2018 at 18:32

1 Answer 1


Ethernet layer 2 doesn't correct errors, it only detects them by frame check sequence (FCS). The algorithm for FCS is CRC with the polynomial G(x) = x32 + x26 + x23 + x22 + x16 + x12 + x11 + x10 + x8 + x7 + x5 + x4 + x2 + x + 1. CRC cannot detect certain paired (even-number) bit error combinations - with a stable connection, these are very rare. A flaky cable could cause undetected errors however.

802.11 uses the same FCS. However, due to the usual encryption more errors can be detected.

10G Ethernet upwards use additional forward error correction (FEC) at layer 1. It can detect more errors and can also correct some error bits (not sure how many right now).

  • Thanks but is there a possibility to see how many errors do i have on my network?
    – yoyo_fun
    Sep 11, 2017 at 10:54
  • @yoyo_fun Your switches, WAPs and NICs usually have counters that you can check, e.g. in Windows netstat -e.
    – Zac67
    Sep 11, 2017 at 11:02

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