4b/5b Encoding
The 4b/5b code-bit stream has a maximum of three consecutive code-cell zeros with a maximum +/-10% cumulative dc component variation from nominal center.
This coding is convenient for ac coupling thereby reducing the noise component in receiver circuitry and is also useful for self-clocking.
FDDI uses 4b/5b coding combined with NRZI
4.5 kB maximum packet size