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Cs 552 Computer Networks Quality Of Service
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| bet | 12/12 | | Sana | 26.12.2023 | | Hajmi | 492 Kb. | | #128375 |
Bog'liq qos-f05Existing Networks - Motivating applications?
- Tele/Video conferencing, video distribution, VPN, games.
- IP+QoS must be better AND cheaper than:
- PSTN with N-way calling
- Cable TV with digital recorders (Tivo)
- Telecom leased lines (ISDN, ATM, SONET)
- Peer to Peer networks
Business Issues - Service provider offers Qos(premium service)
- Must be something customer can:
- Understand
- Counterexample: Complex statistical reasoning
- Verify
- 3rd party?
- How do you know it works? Simulate a DoS attack?
- Reclaim loss if service is not delivered
- If you buy a lock and it doesn’t work, do you try to get your $ back? What if no one tried to break in?
Deployment Issues - Today’s IP operators use simple models to reason about what is a “good network”
- Things you worry about:
- IP packets
- BGP routing
- Simple Service Level Agreements (SLA)
Deployment Issues - QoS introduces extra effort for operators:
- shaping, policing, reservation signaling, per-reservation billing and settlement.
- QoS deployment changes:
- Interface between an ISP and its neighbors
- adds whole new complexities for customer and support personnel,
- creates the need for accurate service auditing,
- Increases the risk of litigation
- Tradeoff:
- Use QoS vs. make sure utilization is low most of the time? Which is easier?
Non-technical Issues summary - Working on QoS for IP for 20 years?
- QoS benefits must significant to overcome all non-technical obstacles.
- Value to users must exceed all costs
- A typical technology adoption problem?
- -> Technically better isn’t always good enough
- QWERTY 10x backward compatibility rule?
- QoS not cheaper, so 1000x?
Over Provisioning Vs. QoS - QoS:
- Insure resources per flow
- Over Provisioning
- Domain of traffic engineering
- Insure sufficient resources aggregate demand
- Formalism for this approach?
Over Provisioning Formalism - Start with Traffic matrix
- Cell is the traffic from source I to dest. J
- Insure network delivers adequate performance for all “expected” matrixes
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