Frame Requirements
nWhy do we need a
minimum length?
Minimum length of
64 bytes guarantees that frame length will be 51.2 microsecs. This is the
maximum roundtrip
delay that can be incurred on an 802.3 LAN operating at 10Mbps, 2.5Km long and
using 4 repeaters
(introduce approx. a 20 bit delay) and includes a safety factor to makeup for
node detection delays.
Recall that collision detection takes
at least two roundtrip delays for worst case scenario! If a station transmits a
shorter frame, it will have
terminated its transmission before discovering that it was involved in a collision.
nChecksum used to detect errors (discarded)