Prioritizing Traffic

Question 1

Managing Network Traffic

Answer 1

• 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

Question 2

Packet shaping

Answer 2

• Packet shaping, traffic shaping
• Control by bandwidth usage or data rates
• Set important applications to have higher priorities
than other apps

Question 3

QoS (Quality of Service)

Answer 3

• 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

Question 4

Managing QoS

Answer 4

• CoS (Class of Service)
  
  • OSI Layer 2
  • 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