QoS - Introduction

Quality of Service

• No longer FIFO
• Classification
  • Identify important traffic flows
  • An if condition
  • When you see packets that look like this, do prioritize or do delay.
  • Any application will use 100% of the available bandwidth, we want to set the network to identify traffic flow and rate limited to this particular speed or maybe accelerated and cut the line in front of other packets.
• Marking
  • Classify bases on an ACL or other conditions
  • Sometimes called Coloring
  • Add the type of Service marking on Layer 3 on the IP header.
  • Classification is the identification process, the marking process is were we go in and we add the Type of Service (ToS)
• Expedited Forwarding
  • VoIP - We usually want great audio quality in a call, go ahead and perform expedited forwarding
    • Create a Voice VLAN for segregation of voice data, ensuring QoS.
  • When you are busy, these are the packets that go first
• Delays
  • In times of congestion throw away certain applications but always deliver others
• Dropping
  • TCP Global Synchronization
    • All are speeding up at the same time and dropping at the same time, this is bad
    • When hitting 100% they will all fall off
      • This is oscillation and is very inefficient since there is a lot of bandwidth unused when a drop happens.
  • A file transfer starts very slow but it speeds up

Network Quality Conditions

• Latency: delay in communication
• Jitter: variation in latency
• Packet Loss: data that was not successfully transferred
• Throughput: rate that data can be transferred

Mission-critical Data

• What matters to the customer?
  • Every organization has different needs
  • We tend to see desired from clients to have a lot of share links from a couple components
• Applications
  • What is the level of importance
  • IP / Subnets / Ports
  • Start to create rules that guarantee a certain level of performance
• Backups
  • Can be very large
  • typically not latency sensitive
  • We want to make sure that it occurs in less activity hours
• Virtual desktop
  • Loads a client that remotes logs you into a virtual desktop (A computer running somewhere else)
• Medical instruments
• Real-time applications
• Each industry is unique!

Expedited Forwarding

• Classification
  • if condition
• Bandwidth limiting
• Traffic shaping
• Queueing strategies
  • Direct it into the VIP line or the BEQ