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dummynet – flexible bandwidth manager and delay emulator

Some terms:

• AQM - Active Queue Management
  • droptail - drop packetss if full
  • CoDel
  • PIE

• pipe - virtual path that emulates a connection with a specified bandwidth, propagation delay, and packet loss pattern.
• Simple pipe internally has attached
  • queue (droptail)
  • scheduler (FIFO)
  • pipe (a link emulator with given badwidth and delay)

• Pipe with CoDel AQM set
  • queue is a dummy queue without any management policy (no droptail). It is not used to buffer incoming packets
  • CoDel scheduler manages internal queues to buffer packets

REMARKS:

• CoDel on queues is ignored when fq-codel is enabled on pipe.
• number of internal queues in fq-codel is condifured by flows parameter