# CoS & QoS Defined

- ## Class of Service:

  - Traffic prioritization
  - Small number of individual classes

- ## Quality of Service:

  - Parameters or attributes that describe a service
    - Bandwidth Reservation
    - End-to-end delay
    - Delay variation (jitter)
    - Error rate
    - Traffic loss

- ## Examples

  - IEEE-802.1p (CoS)
  - IETF RSVP (QoS)
  - ATM Traffic Management

CoS/QoS categorizes traffic to ensure that critical traffic will always flow, despite B/W demands of less important applications.

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