1、 International Telecommunication Union ITU-T Y.2622TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2012) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Next Generation Networks Packet-based Networks Architecture of an independent scalable cont
2、rol plane in future packet based networks Recommendation ITU-T Y.2622 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applications and middleware Y.200Y.299 Network
3、 aspects Y.300Y.399 Interfaces and protocols Y.400Y.499 Numbering, addressing and naming Y.500Y.599 Operation, administration and maintenance Y.600Y.699 Security Y.700Y.799 Performances Y.800Y.899 INTERNET PROTOCOL ASPECTS General Y.1000Y.1099 Services and applications Y.1100Y.1199 Architecture, acc
4、ess, network capabilities and resource management Y.1200Y.1299 Transport Y.1300Y.1399 Interworking Y.1400Y.1499 Quality of service and network performance Y.1500Y.1599 Signalling Y.1600Y.1699 Operation, administration and maintenance Y.1700Y.1799 Charging Y.1800Y.1899 IPTV over NGN Y.1900Y.1999 NEXT
5、 GENERATION NETWORKS Frameworks and functional architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y.2199 Service aspects: Service capabilities and service architecture Y.2200Y.2249 Service aspects: Interoperability of services and networks in NGN Y.2250Y.2299 Numbering, naming
6、 and addressing Y.2300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Packet-based Networks Y.2600Y.2699Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 Carrier grade open environment Y.2900Y.2999 FUTURE NETWORKS Y.3000Y.3499 CLOUD COMPUTING Y.3
7、500Y.3999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T Y.2622 (07/2012) i Recommendation ITU-T Y.2622 Architecture of an independent scalable control plane in future packet based networks Summary Recommendation ITU-T Y.2622 describes the functional architecture
8、of an independent scalable control plane (iSCP) that is achieved by separating the control plane from the data plane in future packet based networks (FPBNs). Basic functional components and reference points of an iSCP are illustrated. History Edition Recommendation Approval Study Group 1.0 ITU-T Y.2
9、622 2012-07-29 13 Keywords Forwarding, FPBN, iSCP, network entity, routing, scalability, separation, virtual network element. ii Rec. ITU-T Y.2622 (07/2012) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, informati
10、on and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwi
11、de basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA
12、 Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administr
13、ation and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisio
14、ns are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to t
15、he possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside
16、of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest
17、 information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T Y.2622 (07/2012) iii Table o
18、f Contents Page 1 Scope 1 2 References. 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 1 5 Conventions 2 6 iSCP architecture 2 6.1 Virtual network element (VNE) . 3 6.2 Control element (CE) . 4 6.3 Service control element (SC
19、E) . 5 6.4 Forwarding element (FE) . 6 6.5 Service processing element (SPE) 8 6.6 Management element (ME) 9 7 Reference points . 10 8 Security considerations . 11 Appendix I Procedures related to iSCP. 12 Bibliography. 16 Rec. ITU-T Y.2622 (07/2012) 1 Recommendation ITU-T Y.2622 Architecture of an i
20、ndependent scalable control plane in future packet based networks 1 Scope This Recommendation describes the architecture, basic functional components, and reference points of an independent scalable control plane (iSCP) that is achieved by separating the control plane from the data plane in future p
21、acket based networks (FPBN), as described in ITU-T Y.2621. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All
22、Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regu
23、larly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Y.2011 Recommendation ITU-T Y.2011 (2004), General principles and general reference model for Next Generation Networks. ITU-T Y.2621 Recommendati
24、on ITU-T Y.2621 (2011), Requirements for an independent, scalable control plane in future, packet-based networks. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 control plane ITU-T Y.2011: The set of functions that controls the operati
25、on of entities in the stratum or layer under consideration, plus the functions required to support this control. 3.1.2 data plane ITU-T Y.2011: The set of functions used to transfer data in the stratum or layer under consideration. 3.1.3 future packet based network (FPBN) ITU-T Y.2621: A network arc
26、hitecture providing the topmost layer(s) of the transport stratum as defined in ITU-T Y.2011. 3.1.4 independent scalable control plane (iSCP) ITU-T Y.2621: An architectural approach of future packet based networks (FPBNs) which consists of separating the control plane from the data plane. 3.1.5 mana
27、gement plane ITU-T Y.2011: The set of functions used to manage entities in the stratum or layer under consideration, plus the functions required to support this management. 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviation
28、s and acronyms: BGP Border Gateway Protocol 2 Rec. ITU-T Y.2622 (07/2012) CE Control Element FE Forwarding Element FIB Forwarding Information Base FPBN Future Packet Based Networks iSCP independent Scalable Control Plane ME Management Element MIB Management Information Base OSPF Open Shortest Path F
29、irst QoS Quality of Service RIB Routing Information Base SCE Service Control Element SPE Service Processing Element VNE Virtual Network Element 5 Conventions In this Recommendation, the following conventions are used: The keyword “entity“ indicates a CE, SCE, FE, SPE, ME or VNE. 6 iSCP architecture
30、The high level requirements stated in ITU-T Y.2621 necessitate defining the following reconstructible components for the iSCP architecture: the control plane, data plane, management plane, control elements (CEs), service control elements (SCEs), forwarding elements (FEs), service processing elements
31、 (SPEs), and management elements (MEs). Figure 6-1 shows the relationship between the control plane, data plane, and management plane, and the relationship of the reconstructible components. Multiple MEs, CEs, SCEs, FEs, and SPEs can form a virtual network element (VNE). Figure 6-1 Three planes and
32、reconstructible components The control plane of an iSCP contains mechanisms for operating the packets and deciding the pathways for user traffic. These mechanisms are implemented in the CEs and SCEs. The data plane of an iSCP contains mechanisms for forwarding and processing user traffic and/or cont
33、rol traffic. These mechanisms are implemented in the FEs and SPEs. The management plane of an iSCP CE CE SCE SCEFE FE SPE SPEData PlaneVNEControl PlaneMEManagement PlaneRec. ITU-T Y.2622 (07/2012) 3 contains mechanisms for dealing with the operation, administration, and management aspects of an iSCP
34、 based network, which is a network based on iSCP as an architectural approach. These mechanisms are implemented in the MEs. Figure 6-2 illustrates the iSCP functional architecture representing the entities of iSCP and the reference points among the entities. Figure 6-2 iSCP functional architecture T
35、he iSCP functional architecture provides two basic operations, VNE configuration and VNE operation. The VNE configuration includes: composing a VNE from CEs, SCEs, FEs, and SPEs based on configuration information from MEs; changing the structure of the VNE depending on the required capacity and flex
36、ibility; and breaking up the VNE. The VNE operation involves operating the constructed VNE as a single conventional network entity, e.g., a router. The iSCP architecture provides three types of reference points, control type reference point C, data type reference point D, and management type referen
37、ce point M. The control type reference point C is used to exchange control information and includes reference points C1, C2, and C3. Reference point C1 is used between CEs and FEs, reference point C2 is used between SCEs and SPEs, and reference point C3 is used between CEs and SCEs. The data type re
38、ference point D is used to forward packets and includes reference points D1, D2, and D3. Reference point D1 is used between FEs and FEs, reference point D2 is used between FEs and SPEs, and reference point D3 is used between FEs and external nodes. The management type reference point M is used to ex
39、change configuration and management information between MEs and CEs/FEs/SCEs/SPEs. 6.1 Virtual network element (VNE) The VNE is a virtual entity composed of multiple CEs, SCEs, FEs, and SPEs based on the configuration information from MEs. The number of individual entities used for the VNE can vary
40、depending on the required capacity and flexibility. The VNE operates as a single conventional network entity, e.g., a router. The VNE hides its internal organization from external nodes and represents a single point of management to entities outside the VNE. Besides management FE FESPESCECEExternaln
41、odeExternalnodeMEVNEC1 C1C2C3D2D1D3 D3MMControlDataManagementReference pointMMM4 Rec. ITU-T Y.2622 (07/2012) information bases (MIBs) of each entity in the VNE, there are also MIBs for the whole VNE. The MIBs of the VNE are held and managed by the MEs. 6.2 Control element (CE) One VNE can include on
42、e or several CEs. The interfaces among the CEs, which are needed when several CEs cooperate with each other within the VNE, will not be defined in this Recommendation. The CE provides the capability to join and leave one VNE based on configuration information from the ME(s). The CE instructs one or
43、a group of FE(s) on how to process packets. The CE generates the packet-forwarding rules for FE(s) and downloads the forwarding rules to the FE(s). To generate these forwarding rules, the CE maintains necessary information in a routing information base (RIB) to compute the most suitable route for in
44、coming packets. The CE updates the RIB in several ways, e.g., by communicating with external nodes through routing protocols via FE(s), by receiving the topology information within the VNE from FE(s), or by receiving the static route configuration from ME(s). Also, the CE maintains routing policies
45、for generating the forwarding rules for FE(s), which indicate specific routes for specific packets. The CE receives such routing policies from ME(s) upon request of network operators, or from SCE(s) upon request from the service control of the SCE(s). The CE manages the CE state information such as
46、entity status and operating status of the CE itself and maintains the MIBs of the CE. The CE allows ME(s) to access these MIBs. Figure 6-3 shows the functions of the CE and its related reference points. Figure 6-3 Control element 6.2.1 VNE composition functions The VNE composition functions support
47、the CE in composing the VNE. The VNE composition functions interact with ME(s) to receive the configuration information through reference point M. The configuration information indicates which other entities the CE should be connected to. Based on the configuration information, the VNE composition f
48、unctions establish or terminate the control sessions with FE(s) through reference point C1 or with SCE(s) through reference point C3. CERouting informationmanagement functionsRouting policymanagement functionsVNE compositionfunctionsCE statemanagement functionsForwarding rulecomputation functionsC1C
49、3MRec. ITU-T Y.2622 (07/2012) 5 6.2.2 Routing information management functions The routing information management functions provide the capabilities to collect and store the routing information required for the VNE to forward packets. The routing information management functions collect the routing information in several ways, e.g., by communicating with external nodes through routing protocols via FE(s) using reference point C1, by receiving the topology information within the VNE from FE(s) through reference point C1, a
