1、 TECHNICAL REPORT ATIS-1000037 Resource Admission Control Overview of Relevant Standards ATIS is the leading technical planning and standards development organization committed to the rapid development of global, market-driven standards for the information, entertainment and communications industry.
2、 More than 200 companies actively formulate standards in ATIS Committees, covering issues including: IPTV, Cloud Services, Energy Efficiency, IP-Based and Wireless Technologies, Quality of Service, Billing and Operational Support, Emergency Services, Architectural Platforms and Emerging Networks. In
3、 addition, numerous Incubators, Focus and Exploratory Groups address evolving industry priorities including Smart Grid, Machine-to-Machine, Networked Car, IP Downloadable Security, Policy Management and Network Optimization. ATIS is the North American Organizational Partner for the 3rd Generation Pa
4、rtnership Project (3GPP), a member and major U.S. contributor to the International Telecommunication Union (ITU) Radio and Telecommunications Sectors, and a member of the Inter-American Telecommunication Commission (CITEL). ATIS is accredited by the American National Standards Institute (ANSI). For
5、more information, please visit . Notice of Disclaimer Stage 2 (Release 8) TS 23.203 3GPP Technical Specification TS 23.228 V8.8.0 (2009), Policy and Charging Control Architecture (Release 8) TS 29.212 3GPP Technical Specification TS 29.212 V8.3.0 (2009), Policy and Charging Control over Gx Reference
6、 Point (Release 8) TS 29.214 3GPP Technical Specification TS 29.214 V8.4.0 (2009), Policy and Charging Control over Rx Reference Point (Release 8) TS 23.002 3GPP Technical Specification TS 23.002 V9.1.0 (2009), Network Architecture (Release 9). TS 23.334 3GPP Technical Specification TS 23.334 V1.1.0
7、 (2009), IMS Application Level Gateway-IMS Access Gateway Interface: Procedures Descriptions (Release 9). 2.5 Packet Cable and Broadband Forum References PKT-TR-ARCH-TR PacketCable 2.0 PKT-TR-ARCH-FR-V06-090528 (2009), Architecture Framework Technical Report.6WT-134 Broadband Forum Working Text 134-
8、Rev.16.01 (2009), Broadband Policy Control Framework.7WT-203 Broadband Forum Working Text 203-Rev.00 (2009), Interaction between Next Generation Fixed and 3GPP Wireless Access.7 2.6 ETSI/TISPAN References8RACS - ETSI ES 282 003 - Telecommunications and Internet Converged Services and Protocols for A
9、dvanced Networking (TISPAN); “Resource and Admission Control Sub-system (RACS); Functional Architecture”. 3 DEFINITIONS, ACRONYMS, sufficient bandwidth is assumed to be traffic engineered from the Customer Premise (users home) to the edge of the Public Network cloud. The latter is the collection of
10、broad public domain networks that enable completion of voice calls as well as internet browsing. Admission control is then accomplished in two parts: a. Customer Premise Control The IPTV set-top box and the VoIP modem control the total amount of simultaneous traffic according to agreed upon limits.
11、This form of control applies to the portion of the path from the Customers Premise to the edge of Public Network cloud. b. Shared/Public Network Control Admission control from the edge of the “public” cloud to the terminating end point can proceed per the discussions in Clauses 6 - 10. 6 RESOURCE AN
12、D ADMISSION CONTROL STANDARDS OVERVIEW PUBLIC NETWORKS The guiding principle behind resource and admission control was stated in the Scope as follows: 1. Determine the requirements for the call/session seeking admission into the network. Examples of such requirements include bandwidth, Quality of Se
13、rvice (QoS), and priority. 2. Determine the availability of resources in the transport layer in order to support the call/session requirements. 3. If the available resources can accommodate the minimum requirements, admit the call/session, else deny. In step (1), the determination of required resour
14、ces for the incoming call/session is carried out via appropriate interactions with application layer functions. The IMS domain is an example of this functionality per specifications defined in 3GPP Release 8 TS 23.228. Table 1 NGN-C240 summarizes relevant resource and admission control standards def
15、ined in various Standards Development Organizations (SDO). Standards applicable to wireless networks are defined in 9Wireless networks may also play a role in the future (e.g., Mobility TV). ATIS-1000037 7 3GPP and the WiMAX Forum the latter effort is compliant with the work done in 3GPP. Standards
16、applicable to wire-line networks are defined in the ITU-T (RACF) and TISPAN (RACS). Cable related standards are defined in CableLabs. Policy work has also commenced in the Broadband Forum this is discussed in Clause 9. Table 1 Summary of Resource and Admission Control Standards ITU-T 3GPP/SAE TISPAN
17、 WiMax CableLabsPolicy Decision PD-FE PCRF SPDF, A-RACF (partial)PCRF, PDF PAM, PS Policy Enforcement PE-FE PCEF RCEF10PCEF CMTS Transport Resource Control TRC-FE - A-RACF (partial) - - PD-FE (Policy Decision Functional Entity) TRC-FE (Transport Resource Control Functional Entity) PE-FE (Policy Enfo
18、rcement Functional Entity) PCRF (Policy and Charging Rules Function) PCEF (Policy and Charging Enforcement Function) SPDF (Service Policy Decision Function) A-RACF (Access Resource Admission Control Function) PDF (Policy Distribution Function) PAM (PacketCable Application Manager) PS (Policy Server)
19、 CMTS (Cable Modem Termination System) There are several aspects that are common to all standards and one significant difference as follows: 1. Policy Decision Function: All standards have a Policy Function (the names differ) that is responsible for interacting with the application layer to determin
20、e the resource requirements of the incoming call/session. This functionality serves step (1) of the resource and admission control principle stated in the scope. 2. Policy Enforcement: All standards have a Policy Enforcement Function (the names differ) that is responsible for ensuring the action nee
21、ded in the underlying transport layer to admit or deny the call/session (e.g., packet policing, packet marking, QoS and priority support). This functionality is equivalent to step (3) of the resource and admission control principle stated in the scope. 3. Transport Resource Control: The wire-line st
22、andards define a dedicated Transport Resource Control function that is solely responsible for determining adequacy of available resources in the underlying transport layer. This functionality is equivalent to step (2) of the resource and admission control principle stated in the scope. The ITU-T RAC
23、F fully defines this functionality. The TISPAN RACS partially defines this as needed in access networks only; it further defines this functionality in terms of an access RACF. For wireless access networks, the 3GPP 10Note that legacy RCEFs can only enforce pre-configured or seldom changed policies.
24、In such cases, per session policy enforcement may involve interaction with a Border Gateway Function. ATIS-1000037 8 architecture invokes determination of radio access resources as part of the bearer binding association. This Technical Report provides discussions on the use of these standards by foc
25、using on these similarities and difference. It also touches on some architectural aspects for these functionalities. 7 GATEWAY SUPPORT FOR POLICY FUNCTIONS The Policy Decision and Enforcement functions have been defined logically for wireless and wire-line networks (see Table 1). Specifically, Gatew
26、ays to network domains are embodied with a wide range of functionality to process incoming call/session initiation prior to formal admission into the underlying network. Gateways can serve as “gatekeepers” for access networks. They also provide interconnection processing between network domains over
27、 the end-to-end path of calls/sessions. Architectural manifestations of these logical functions have also received some attention. For wireless networks, the Evolved Packet Core in 3GPP uses the Packet Data Node (PDN) Gateway. ATIS and ITU-T have defined functionality for the Session Border Controll
28、er with applications for NGNs. 7.1 PDN Gateway for Wireless Networks Two Gateways have been mentioned by 3GPP for support in wireless networks TS 23.203, TS 23.401. They are: Gateway General Packet Radio Service (GPRS) Support Node Gateway support for GPRS bearers Packet Data Node (PDN) Gateway Gate
29、way support for the Evolved Packet Core The Policy and Charging Enforcement Function (PCEF) resides in these Gateways TS-23-203. Policy control related to QoS is enforced by this function at the Gateway in question. The Policy and Charging Rules Function (PCRF) is depicted as an independent entity n
30、ot residing in any Gateway TS 23.203, TS 23.401, TS 23.402. The possibility of locating in within any specific gateway is for further study. 7.2 Session Border Controller for Wireline Networks The Session Border Controller (SBC) Gateway functionality has been defined in ATIS A-1000026 and the ITU-T
31、Y.2012-Sup1. Signaling Path (control plane) functions provide the necessary signaling interactions with the service/application layer. Examples of Signaling Path functions include protocol translation and inter-working, call/session-based routing, and signaling encryption and decryption. Media Path
32、functions provide interactions with the underlying transport. Examples include packet policing and marking, opening and closing of pinhole/firewall, and Connection Admission Control (CAC). The SBC Media Path functions A-1000026 support a host of Policy Enforcement requirements for admission control.
33、 These include access admission control, bandwidth allocation, enforcement of rules based on maximum number of simultaneous calls/sessions, monitoring bandwidth usage, support for QoS and priority, and packet policing/marking. The Policy Enforcement functions defined in various SDOs (Table 1) can th
34、en be considered to be distributed in the appropriate Media Path functions in the SBC. To date, a function dedicated for Resource and Admission Control Policy Decision support has not been defined for the SBC. It is possible to centralize this function in a central server for a network domain. This
35、possibility is for further study. It is also possible to distribute the functionality by dedicating ATIS-1000037 9 a function for this purpose in the Signaling Path of the SBC. This would enable all policy related interactions to be completed in the SBC. 7.3 Other Gateways Several other Gateways hav
36、e received mention in various SDO documents. They include the following: IMS Access Gateways TS 23.228, TS 23.334 The IMS Application Level Gateway (IMS-ALG) and IMS Access Media Gateway interact via the Iq interface for the purpose of gate control and traffic policing between an IP-Connection Netwo
37、rk (IP-CAN) and an IMS domain. Transition Gateway/Border Control Function TS 23.002, TS 23.228 The Transition Gateway (TrGW) is located in the media path and is controlled by an Interconnect Border Control Function (IBCF). It provides functionality for network address/port translation and IPv4/IPv6
38、protocol translation. The precise role of these gateways in the end-to-end admission control policy process as well as potential overlap of various functionalities (e.g., Policy Enforcement Function) across them is for further study. 8 WIRELESS NETWORKS 3GPP STANDARDS Standards pertaining to wireles
39、s networks are advanced in 3GPP WiMAX technology standards are stated as being 3GPP compliant. All resource and admission control development related to wireless networks should comply with 3GPP standards. 3GPP Release 8 functionality supporting admission control is described as part of the Policy a
40、nd Charging Control (PCC) architecture TS 23.203. The Policy Decision functionality is contained in the Policy Charging and Rules Function (PCRF). The Policy Enforcement functionality is contained in the Policy and Charging Enforcement Function (PCEF). PCRF and PCEF interactions supporting Resource
41、and Admission Control are as follows: Initial PCRF and Application Layer Interaction: The Proxy Call Session Control Function (P-CSCF)11which is part of the IMS Application Function layer submits a QoS authorization request to the PCRF via the Rx Reference Point. This request includes call/session b
42、andwidth requirements, priority, media type/flow description, and event triggers. Rx Reference Point interactions are carried out via appropriate DIAMETER protocol Attribute Value Pairs (AVP) TS 29.214. PCRF-PCEF Interaction: The PCRF processes the request, authorizes resources, and provisions PCC r
43、ules at the PCEF via the Gx Reference Point. The PCEF requests the establishment/modification of EPS resources. The Bearer Binding Function (BBF) associates the service flow with the appropriate bearers that can provide the desired QoS. The availability of Radio Access Network (RAN) resources is che
44、cked by the eNodeB. The E-UTRAN admits the corresponding bearer/resources only if resources are available. The PCEF performs the necessary enforcement functions such as packet policing, packet marking, and opening of pinhole. Gx Reference Point interactions are carried out via appropriate DIAMETER p
45、rotocol AVPs TS 29.212. Final PCRF-Application Layer Interaction: Once the PCEF completes required enforcement actions, the PCRF responds back to the P-CSCF via the Rx Reference Point indicating IP-CAN support (successful allocation of required resources provided the P-CSCF subscribes to this event)
46、 or denial (resource unavailability) of the impending media flow. 11Note that the PCRF can interact with any application function that supports the Rx interface. ATIS-1000037 10 Note that while there is no dedicated Transport Resource Control Function defined in 3GPP, radio resource availability and
47、 access transport resource availability is determined as part of the bearer binding association. 9 WIRELINE NETWORKS ITU-T RACF The ITU-T Resource and Admission Control Function (RACF) Y.2111 standard applies to all NGN networks. Given that wireless network admission control standards are governed b
48、y 3GPP, all wire-line network admission control requirements can be specified by RACF. It was noted that TISPAN RACS is similar to RACF regarding the presence of the Policy Decision and Policy Enforcement functionality. However, the Transport Resource Control function specified in TISPAN RACS is den
49、oted by an access RACF function. TISPAN RACS assumes that core backbone wire-line networks have sufficient resources traffic engineered/pre-provisioned and hence do not need any transport control functionality. Hence, it can be stipulated that ITU-T RACF fully governs all wire-line resource and admission control requirements TISPAN RACS can be viewed as a subset of ITU-T RACF. 9.1 RACF Transport Resource Control Architecture The Policy Decision and Enforcement Functions in R
