1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T Y.1312TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (09/2003) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT GENERATION NETWORKS Internet protocol aspects Transport Layer 1 Virtual Private Network generic requirements an
2、d architecture elements ITU-T Recommendation Y.1312 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 aspects Y.300Y.39
3、9 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, access, network capab
4、ilities 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 NEXT GENERATION NETWORKS Frameworks and functiona
5、l 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 and addressing Y.2300Y.2399 Network manageme
6、nt Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. Y.1312 (09/2003) i ITU-T Recommendation Y.1312 Layer 1 Virtual Private Network generic r
7、equirements and architecture elements Summary This Recommendation specifies service definition, service scenarios, service requirements and service architecture elements on Layer 1 Virtual Private Network (L1 VPN). Source ITU-T Recommendation Y.1312 was approved on 13 September 2003 by ITU-T Study G
8、roup 13 (2001-2004) under the ITU-T Recommendation A.8 procedure. Keywords Architecture, Layer 1, Layer 1 VPN, Requirement, Virtual Private Network, VPN. ii ITU-T Rec. Y.1312 (09/2003) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of t
9、elecommunications. 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 worldwide basis. The World Tel
10、ecommunication 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 Resolution 1. In some
11、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 administration and a recognized
12、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 provisions are met. The words “sh
13、all“ 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 the possibility that the p
14、ractice 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 of the Recommendation dev
15、elopment 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, implementors are cautioned that this may not represent the latest information and are ther
16、efore strongly urged to consult the TSB patent database. ITU 2004 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. Y.1312 (09/2003) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbrev
17、iations 2 5 Service definition and service reference model 3 5.1 Basic L1 service reference model and features 3 5.2 L1 service categories, L1 VPN reference model and definition 3 6 Service scenarios 5 6.1 Multi-service backbone 5 6.2 Carriers carrier . 6 6.3 L1 resource trading. 6 6.4 Inter-SP L1 V
18、PN 7 7 Service requirements 8 8 Service architecture elements . 10 8.1 C-plane and U-plane combinations 10 8.2 Description of service examples based on C-plane and U-plane combination 11 8.3 L1 VPN functional model 12 9 Security aspects 16 Annex A Functions performed by the CE in a L1 VPN . 17 Appen
19、dix I Relationship with L2/L3 VPNs 18 I.1 Multipoint connectivity for L3/L2 VPN and layer 1 VPN. 18 I.2 C/U-planes for L3/L2 VPN and layer 1 VPN 18 ITU-T Rec. Y.1312 (09/2003) 1 ITU-T Recommendation Y.1312 Layer 1 Virtual Private Network generic requirements and architecture elements 1 Scope This Re
20、commendation specifies service definition, service scenarios, service requirements and service architecture elements on Layer 1 Virtual Private Network (L1 VPN). L1 VPN has specific features compared to generic VPN described in ITU-T Rec. Y.1311, such as connections between CEs rather than tunnels b
21、etween PEs, and C-plane/U-plane separation. In addition, L1 VPN has features such as connectivity restriction within limited CEs and per-VPN C-plane functionalities, which are achieved by additional functionalities to the basic L1 network. To this end, L1 VPN provides customers with large capacity U
22、-plane resources with a different set of C-plane functionalities. Thus, new kinds of services are expected to emerge, including multi-service backbone, carriers carrier and L1 resource trading. This Recommendation addresses service features of L1 VPN including those mentioned above, and also describ
23、es service requirements and service architecture elements. In addition, this Recommendation describes several scenarios where the merits of L1 VPN are well expected. 2 References The following ITU-T Recommendations and other references contain provisions, which, through reference in this text, const
24、itute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All 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 Re
25、commendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 1 ITU-T Recommendation G.805 (2000), Generi
26、c functional architecture of transport networks. 2 ITU-T Recommendation G.8080/Y.1304 (2001), Architecture for the automatic switched optical network (ASON). 3 ITU-T Recommendation Y.1311 (2002), Network Based VPNs Generic architecture and service requirements. 3 Definitions This Recommendation defi
27、nes the following terms: 3.1 L1 VPN: A network formed by a set of CEs and network resources between CEs. A set of CEs is managed by the same authority. Network resources between CEs are provided by the service provider, and may include links, connections and C-plane functionalities. Refer to ITU-T R
28、ec. Y.1311. 3.2 NB L1VPN: Refer to ITU-T Rec. Y.1311. 3.3 CE: The entity receiving U-plane and C-plane service provided by the network to which it is attached. Refer to ITU-T Rec. Y.1311. 3.4 PE: The entity within the Network connected to CE, that provides service to customers. Refer to ITU-T Rec. Y
29、.1311. 2 ITU-T Rec. Y.1312 (09/2003) 3.5 P: The entity within the network, and connected to P or PE devices. Refer to ITU-T Rec. Y.1311. 3.6 link: U-Plane resource connecting adjacent network devices in the same layer (in the OSI sense) and within the same layer network (in the G.805 sense), e.g. co
30、nnecting CE and PE, PE and P. 3.7 connection: For L1 VPN, a connection is established between a pair of CEs. See Annex A for a more detailed description. 3.8 customer: The entity that has authority over a set of CEs within the same VPN (e.g. the owner of the CEs). The customer is the billable entity
31、 to which L1 VPN service is provided. The customer of a Layer 1 VPN has typically at least 3 CEs, while the customer of a private line service has exactly two CEs. 3.9 shared U-plane: U-plane in which link resources can be multiplexed (over time) between different VPNs. At any instant in time the re
32、sources are either dedicated to one VPN or are unallocated. 3.10 dedicated U-plane: U-plane in which link resources are allocated exclusively to a specific VPN. 3.11 shared C-plane: C-plane in which the same control resources are used by multiple VPNs. 3.12 dedicated C-plane: C-plane in which contro
33、l resources are allocated exclusively to a specific VPN. 3.13 Shared U-Plane Private Network (SUPN): L1VPN with shared U-plane. 3.14 Dedicated U-Plane Private Network (DUPN): L1VPN with dedicated U-plane. 3.15 Shared C-Plane Private Network (SCPN): L1VPN with shared C-plane. 3.16 Dedicated C-Plane P
34、rivate Network (DCPN): L1VPN with dedicated C-plane. 3.17 site: The network behind a CE, that is managed by the same authority as the CE. 4 Abbreviations This Recommendation uses the following abbreviations: AAA Authentication, Authorization and Accounting CE Customer Edge CNM Customer Network Manag
35、ement CSM Customer Service Management DCN Data Communication Network P Provider PE Provider Edge PM Performance Measurement VPN Virtual Private Network ITU-T Rec. Y.1312 (09/2003) 3 5 Service definition and service reference model 5.1 Basic L1 service reference model and features 5.1.1 Basic L1 serv
36、ice reference model Figure 5-1 shows the reference network model where a customer edge (CE) is using a L1 service. Separation between the service provider and the customer is provided by L1 service interface. Basic L1 service provides U-plane resources between CEs in a point-to-point manner, i.e. co
37、nnection oriented. Y1312_F5.1Service provider networkL1 service interfacesCE CEFigure 5-1/Y.1312 Basic L1 service reference model 5.1.2 Basic L1 services features Basic layer 1 service is characterized in terms that include: Connectivity: between a pair of CEs; Capacity: for example, bit rate for a
38、TDM service; Transparency: for example, for a SDH network, overhead transparency etc.; Availability: the percentage of time that the quality service meets the agreed criteria. To achieve the required level of availability for the customer connections, the service providers network may use restoratio
39、n or protected resources; Performance: e.g., number of error seconds per month. 5.2 L1 service categories, L1 VPN reference model and definition 5.2.1 L1 service categories Layer 1 services can be categorized based on the combination of connectivity features (U-plane) and service control capability
40、(C-plane) available to the customer. A CE is associated with the service interface between a customer site and the network. Type 1 enables one connection between a pair of CEs. Type 2 enables multiple connections among a set of CEs. Type 2 may involve a variety of C-plane types depending on the cust
41、omer. Table 5-1 shows the classification of the services. Layer 1 VPN can be defined as a subset of the Type 2 service category. Compared to Type 1 services, the Layer 1 VPN service has features such as separate policy per VPN and distribution of membership information. For either Type 1 or Type 2 s
42、ervices, connections are point-to-point and can be permanent, soft-permanent, or switched. For a static service, the network is responsible for the management of both the network infrastructure and the end user connections. For dynamic service, the network is only responsible for the configuration o
43、f the infrastructure; end user connections are established dynamically by the network. 4 ITU-T Rec. Y.1312 (09/2003) Table 5-1/Y.1312 Types of layer 1 services including layer 1 VPN Types of Layer 1 services Static service Permanent connection service (classic private line service) Type 1 Single con
44、nection service (one customer between two CEs) Dynamic service Switched connection service Customer-controlled soft permanent connection service Static service Private network service Type 2 Multiple connection service (one customer; three or more CEs) Dynamic service Layer 1 VPN Customer-controlled
45、 soft permanent connection service Switched connection service Separate policy per VPN, and distribution of membership information within the group of CEs NOTE Single connection service may be supported by multiple connections (e.g. protection purpose). 5.2.2 L1 VPN reference model Figure 5-2 shows
46、a reference model for L1 VPN. Y.1312_F5.2CE CECE CEService provider networkPEPEPEPEPVPN#1VPN#2CEL1 VPN service interfacesfor Customer#1L1 VPN service interfacesfor Customer#2CEFigure 5-2/Y.1312 L1 VPN reference model NOTE 1 Customer may outsource management of VPN to a different organization. In thi
47、s case, this organization has an authority to manage the VPN. NOTE 2 The CE and PE are logical entities; the implementation is dependent on the network application. For example: a) The CE and PE may be implemented in the same building, or even in the same equipment. In this case, the CE and PE are s
48、till regarded as logically separated entities. b) There could be a network on the user side of CE, i.e. site. c) The link between the CE and PE may be provided by the (static) network of another network operator. ITU-T Rec. Y.1312 (09/2003) 5 5.2.3 L1 VPN service definition and features A Layer 1 VP
49、N is a VPN whose U-plane operates at layer 1. Thus, the L1 VPN service provides optical or TDM connections between CEs. In addition to the service features of basic L1 service described above, the Layer 1 VPN service has the following features: U-plane: Layer 1 connectivity is provided to a limited set of CEs (This set of CEs forms the Layer 1 VPN membership.); C-plane: Some level of control and management capability is provided to the customer. 6 Service scenarios 6.1 Multi-service backbone Y.1312_F6.1VPN#1V
