# <center><i class="fa fa-edit"></i> QoS Fundamentals Cont. </center>
###### tags: `Internship`
:::info
**Goal:**
- [x] Understand fundamentals of QoS applications Cont.
- [x] QoS Architecture Preview

**Resources:**
[Notes Page](https://hackmd.io/@j-chen/rkUz8DeUw)
:::
### QoS Fundamentals Cont.
- Quantitative service: AKA "guaranteed"
- Delivers hard QoS
- Highest QoS
- Guarantees network performance in deterministic/statistical terms
- Good for mission-critical applications
- Qualitative service: AKA "differentiated"
- Soft/relative QoS
- Ex: priority service
- Best effort servce: no guarantees
- All traffic equal
- Good for data traffic (email, etc.)
- Lowest level service
- Per-flow QoS: assurance to individual flows (applications)
- Per-flow classification: differentiates different flows
- Per-class QoS: classify groups based on criteria (QoS requirement, organization, app type, protocol family)
- Assurance to class
- Everything in same class has same QoS
- Per-class classification
- Realization of QoS: bandwidth planning
- Bandwidth over-provisioning: upgrade infrastructure if you need more
- Price: very costly
- Bandwidth management via QoS mechanisms
- QoS mechanisms:
- Classification
- Admission control
- Channel access
- Resource reservation
- Scheduling
- Policing
### QoS Architecture Preview