QoS

Theoretical Need for QoS:

·         Root Cause: Resource Contention

o   Multiple traffic flows sharing same logical or physical interface

§  Same or multiple applications

§  Each application has its own requirements(delay, packet loss, bandwidth, etc)

·         Resource Contention results

o   Due to this queuing of traffic occurred at layer-2 devices

o   It results,

§  Packets may be delayed or dropped

§  Effective flow through decreases

§  Delay or Jitter(differences in delay) exceed thresholds

·         Possible Solutions:

o   Best solution: Avoid Contention

§  Don’t over-provision network, so maintain enough bandwidth all applications.

§  Add new physical links and/or new physical devices

o   Next best solution: QoS

§  Network congestion is controlled on the links

§  Delay/loss/jitter/Throughput are controlled on per-hop-basis

§  QoS is band-aid for network but not a permanent solution

§  Longterm solution is add better and required hardware

There is too much contention, QoS also not helped