pfifo_fast is the default, a FIFO queue. This has three
bands (queues), where type of service packets are placed in queue 0 (the
lowest level), and unless queue 0 is empty, packets from queue 1 won’t
be sent, and the same for queue 2.
token bucket filter passes packets arriving at a rate
that does not exceed some set rate, but allows bursts in excess of this
rate (leaky bucket).
stochastic fairness queueing SFQ is a algorithm that
uses randomness (hashing) to set a “fair” throughput for each session
that sends packets. Each packet is hashed and added to a queue, and each
queue is processed in round robin fashion.
Random Early Drop to avoid congestion, RED
pre-emptively drops packets before the buffer becomes completely full.
It uses some heuristics based on packet size to figure out which packets
to drop.