Differentiated Services (DiffServ)

• More recent than the IntServ approach. Also proposed by the IETF.

• DiffServ provides absolute or relative per-hop QoS guarantees to flow aggregates (classes).

• Evolved into two service models:

  • premium service provided by Expedited Forwarding (EF)
  • assured service provided by Assured Forwarding (AF)

• Advantages over IntServ:

  • scalability (routers maintain only per-class state)
  • network management similar to existing IP networks

• Major drawbacks:

  • all-or-nothing upgrade and dramatic operational changes
  • lack of demand and lack of support from router vendors

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