Flow-Based Random Early Detection

Flow-Based Random Early Detection
Flow-Based RED (FRED) is an extension to WRED that ensures no single
flow can monopolize all the buffer resources at the output interface
queue. With normal WRED, a packet dropped from a TCP source causes
the source to reduce its transmission, whereas a packet dropped from a
noncompliant source, like UDP, does not. This may have the end effect
of the polite flows being drowned out by the impolite flows. Flow-based
RED prevents this by maintaining minimal information about the buffer
occupancy of each flow. In this way, when a flow exceeds its share of the
output buffer, it is dropped. This is in contrast to the more random
buffer drops of normal WRED. This feature first became available in IOS
version 12.0(3)T.