Prioritizing Traffic

Managing Network Traffic
  • Many different devices
    • Desktop, laptop, VoIP phone, mobile devices
  • Many different applications
    • Mission critical applications, streaming video, streaming audio
  • Different apps have different network requirements
    • Voice is real-time
    • Recorded streaming video has a buffer
    • Database application is interactive
  • Some applications are "more important" than others
    • Voice traffic needs to have priority over YouTube
Packet shaping
  • Packet shaping, traffic shaping
  • Control by bandwidth usage or data rates
  • Set important applications to have higher priorities than other apps
QoS (Quality of Service)
  • Prioritize traffic performance
    • Voice over IP traffic has priority over web-browsing
    • Prioritize by maximum bandwidth, traffic rate, VLAN, etc.
  • Quality of Service
    • Describes the process of controlling traffic flows
  • Many different methods - Across many different topologies
Managing Q0S
  • CoS (Class of Service)
    • OSI Layer2
    • Ethernet frame header in an 802.1q trunk
    • Usually applied in the intranet (not from an ISP)
  • Differentiated Services (DiffServ)
    • OSI Layer 3
    • QoS bits are enabled in the IPv4 header
    • Bits are set external to the application
    • Routers and switches have to play along
  • DSCP (Differentiated Services Code Point)
    • DS(Differentiated Services) field in the IP header

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