Study
CS-723 route
Unit 5 · Lesson 4 of 6 6 min

The Checksum Method

The Internet checks its own packets with a clever bit of addition that wraps its carries around.

What this unit covers

Unit 5: Error Detection and Correction

  1. 1 Types of Errors: Single-Bit and Burst ErrorsHow the wire lies: one bit flipped, or a whole burst swept away by a single spike of noise. · 3 min
  2. 2 Redundancy, Error Detection and Error CorrectionTo catch a lie, send a little extra truth along with the message. · 4 min
  3. 3 Parity Check: Simple and Two-Dimensional ParityParity is a one-bit lie detector: it catches a flipped bit, but two flips at once slip straight past it. · 4 min
  4. 4 The Checksum MethodThe Internet checks its own packets with a clever bit of addition that wraps its carries around. · 6 min
  5. 5 Cyclic Redundancy Check (CRC)Ethernet and Wi-Fi trust a strange kind of division, with no carries at all, to catch almost every damaged frame. · 5 min
  6. 6 Detection and Correction of Burst ErrorsOne flipped bit is easy to spot, but a burst of damage can fool every checker you've met — here's why. · 9 min