Integrated services

IntServ (Integrated Services ) is a fine-grained Quality of Service ( QoS ) techniques for prioritization of IP data packets through a network scheduler. In contrast to the DiffServ method the resources for individual connections and not for traffic classes are required.

The protocol for the construction of resource reservation, the Resource Reservation Protocol (RSVP) is used. A router can run on its available capacities book and respond to a request for QoS assurance with a positive or negative response. In the case of a positive answer, the router ensures compliance with the required characteristics for the entire session duration. Once made ​​assurances may not be circumcised. To achieve the priority, resources can be reserved in each network element by means of a transportation contract with fixed parameters. Therefore, each node must be in the involved network (routers, switches, etc. ) proceed according to the IntServ process and all available resources must also be managed. IntServ provides certain requirements to the network as the maximum packet delay, bandwidth, and resource reservation. The access management happens according to the application made by the applications requirements and available resources. The specifications are signaled or replaced by TSPEC (Traffic Descriptor ) and RSPEC ( reservation Characteristics ) of the TOS field ( Type of Service ) of the IP header (IPv4). IntServ guarantees the QoS properties only as long as the applications send data in accordance with the previously exchanged specifications.

The Intserv process has two basic classes of service:

  • Guaranteed QoS ( guaranteed service quality) offers a guaranteed transfer rate and a quantitative assessment of the maximum delay caused by queues in the network. Furthermore, it is assured that no packets are lost due to full queue.
  • Controlled Load merely makes the promise that a very large part of the incoming packets will not be discarded by the router and that the delay through the queue goes to zero. However, no specific commitments in figures are expressed.
415409
de