Resource ReSerVation Protocol: The RSVP protocol, RFC 2205
, is used by a host to request specific qualities of service from the network for particular application data streams or flows. The network responds by explicitly admitting or rejecting RSVP requests.
DiffServ networks classify packets into one of a small number of aggregated flows or "classes", based on the DiffServ codepoint (DSCP) in the packet's IP header. This is known as behaviour aggregate (BA) classification (RFC 2475
). At each DiffServ router, packets are subjected to a "per-hop behaviour" (PHB), which is invoked by the DSCP (RFC 2474
The integrated services architecture 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 architecture is a set of service definitions; the current set of services consists of the controlled load and guaranteed services. The architecture assumes that some explicit setup mechanism is used to convey information to routers so that they can provide requested services to flows that require them. While RSVP is the most widely known example of such a setup mechanism, the IntServ architecture is designed to accommodate other mechanisms.
The Application Function (AF) is an element offering applications that require the control of IP bearer resources . The AF is capable of communicating with the PCRF to transfer dynamic QoS-related service information. One example of an AF is the P-CSCF of the IM CN subsystem.
An AF session is established by an application level signalling protocol offered by the AF that requires a session set-up with explicit session description before the use of the service. One example of an AF session is an IMS session.
AF session signalling:
AF session signalling is used to control the AF session. One example of AF session signalling is SIP/SDP.
The process whereby the Policy and Charging Rules Function (PCRF) indicates to the Policy and Charging Enforcement Function (PCEF) how to control the IP-CAN bearer. Policy control includes QoS control and/or gating control.
For the purpose of the present document, the following abbreviations apply:
Access Point Name (*)
DiffServ Code Point
GSM/EDGE Radio Access Network (*)
Gateway GPRS Support Node (*)
Hypertext Transfer Protocol (*)
IP Multimedia Subsystem
Local Area Network
Label Distribution Protocol
Multiprotocol Label Switching Architecture
Policy and Charging Control
Policy and Charging Enforcement Function
Per Hop Behaviour
Policy and Charging Rules Function
Radio Network Controller (*)
Session Description Protocol
Session Initiation Protocol (*)
Simple Network Management Protocol (*)
Traffic Flow Template (*)
This abbreviation is covered in TR 21.905
, version 4.2.0.