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Cs 552 Computer Networks Quality Of Service
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| bet | 9/12 | | Sana | 26.12.2023 | | Hajmi | 492 Kb. | | #128375 |
Bog'liq qos-f05Recap of RSVP - PATH message
- sender template and traffic spec
- advertisement
- mark route for RESV message
- follow data path
- RESV message
- reservation request, including flow and filter spec
- reservation style and merging rules
- follow reverse data path
- Other messages
- PathTear, ResvTear, PathErr, ResvErr
Why did IntServ fail? - Economic factors
- Deployment cost vs Benefit
- Is reservation, the right approach?
- Is per-flow state maintenance an issue?
- More about QoS in general …
What is the Problem? - Goal: provide support for wide variety of applications:
- Interactive TV, IP telephony, on-line gamming (distributed simulations), VPNs, etc
- Problem:
- Best-effort cannot do it?
- Intserv can support all these applications, but
Differentiated Services (Diffserv) - Build around the concept of domain
- Domain – a contiguous region of network under the same administrative ownership
- Differentiate between edge and core routers
- Edge routers
- Perform per aggregate shaping or policing
- Mark packets with a small number of bits; each bit encoding represents a class (subclass)
- Core routers
- Process packets based on packet marking
- Far more scalable than Intserv, but provides weaker services
Diffserv Architecture - Ingress routers
- Police/shape traffic
- Set Differentiated Service Code Point (DSCP) in Diffserv (DS) field
- Core routers
- Implement Per Hop Behavior (PHB) for each DSCP
- Process packets based on DSCP
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