What is QoS?

  • http://docwiki.cisco.com/wiki/Quality_of_Service_Networking
  • Quality of life insurance
  • The ability to dictate traffic treatment

    • Prioritization.
      • Only happens with congestion.
    • Shaping / Policing.
      • Shaping: Mold the traffic down to a specific speed.
      • Policing: ‘evil’ traffic types ( p2p / video ).
    • Advanced Strategies ( WRED – Weighted random early detection)
      • Drop selective TCP streams so it won’t hit max.
  • Strategies to fight the enemy
    • Delay ( how long it takes for a Packet A to get to the other side).
    • Jitter ( Delay variation, Times between Packets A,Packet B,and Packet C taking to get to the other side)
    • Packetloss
Audio Requirements Video Requirements
Jitter< 30ms< 30ms
Delay< 150ms< 150ms
Loss < 1%< 1%
QoS:DSCP EFDSCP AF41
BandwithLowHigh

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