IntServ (IS) Summary
- Most used QoS Management mechanisms have: IntServ (reserve resource) and DiffServ (Not reserve resource, but classify the traffic)
- Is a resource reservation technology
- Allows both unicast and multicast transmissions.
- By allowing control mechanism, it can monitor and control resource for controlling real-time service with required E2E packet delay.
- Applications request reservations for network resources which are granted or denied based on resource availability
- Based on application identification (IPv4 sockets or IPv6 Data Flow Id)
- Provides for a rich E2E QoS solution, by way of end-to-end signalling, state-maintenance (for each RSVP-flow and reservation), and admission control at each network element
- Provides QoS services on a per flow basis where a flow is a packet stream with common source address, destination address and port number.
- Is a flow-based approach to QoS using resource reservation.
- Reservations are made per simplex flow
- IntServ routers must maintain per flow state information.
- Routers managed and Routers need to maintain per-flow state and are generally not considered to be scalable.
- Service guarantees are end-to-end on a per-flow basis
- While RSVP is the most widely known example of such a setup mechanism, the IntServ architecture is designed to accommodate other mechanisms.
- The Integrated Services (IntServ) model builds upon Resource Reservation Protocol (RSVP)
- RSVP (Resource ReSerVation Protocol) is a signaling protocol used by IntServ to set up resources in the sender to receiver direction
- Resource reSerVation Protocol (RSVP) is used to reserve the resources at intermediate routers between sender and receivers, and is marked a path of reserved resources for an application flow
- Senders specify the resource requirements via a PATH message that is routed to the receiver
- Receivers reserve the resources with a RESV message that follows the reverse path
- IntServ is a framework for gluing network elements together to provide end-to-end QoS for Some specific end-to-end QoS services
- IntServ framework was developed within IETF to provide individualized QoS guarantees to individual sessions.
- The integrated services architecture in RFC 1633 defined a set of extensions to the traditional best effort model of the Internet with the goal of allowing end-to-end QOS to be provided to applications.
- One of the key components of the IntServ architecture is a set of service definitions; the current set of services consists of the controlled load and guaranteed services.
- The IntServ service model is proposing includes two sorts of service targeted towards real-time traffic: guaranteed and predictive service.
- According to Controlled Link-Sharing and Explicit Signaling control, it can provide integrated “Guaranteed” and “Predictive” real-time service. It integrates these services with controlled link-sharing, and it is designed to work well with multicast as well as unicast.
Please refer to http://tw.myblog.yahoo.com/jw!HBFkhByWERmsTjQ93kTmwdsbhyg-
- IntServ is very powerful but has some severe drawbacks:
- Reservations are made by endpoints
- IntServ is multicast-oriented
- Flow: a distinguishable stream of distinct IP datagrams
- Soft-state:
- Two key IntServ features:
- Applications using IntServ can request two basic service-types:
- Components of this IntServ architecture:
- IntServ Mechanisms
- A signaling protocol is needed to carry the R-spec and T-spec
- The Integrated Services Model can be divided into two parts – the Control and Data Planes
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