Network Working Group Tomonori Takeda (Editor) Internet Draft NTT Proposed Status: Informational Expires: August 2005 February 2005 Applicability analysis of GMPLS protocols to Layer 1 Virtual Private Networks draft-takeda-l1vpn-applicability-02.txt Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, or will be disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract This document provides an applicability analysis on the use of Generalized Multiprotocol Label Switching (GMPLS) protocols and mechanisms to satisfy the requirements of Layer 1 Virtual Private Networks (L1VPNs). In addition, this document identifies areas where additional protocol extensions or procedures are needed to satisfy the requirements of L1VPNs, and provides guidelines for potential extensions. T.Takeda, et al. Expires August 2005 [Page 1] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 0. Summary (This section to be removed before publication as an RFC.) 0.1. Summary This document describes the applicability of existing GMPLS protocols and mechanisms to support L1VPNs requirements as described in [L1VPN-FW]. In addition, this document identifies several areas where additional protocol extensions are needed to meet the full set of L1VPN services requirements. 0.2. Where does it fit in the picture of the IETF Work The IETF is responsible for GMPLS protocols. L1VPNs are a new layer 1 service that adds new requirements for GMPLS as identified in [L1VPN-FW]. IETF VPN related work areas may also have points of interaction with the content of this document. 0.3. Justification The L1VPN mailing list was set up to discuss issues related to L1VPNs. This document is intended to progress the work by showing the applicability of existing mechanisms and potential solutions (see section 0.4) and identifying several areas where additional work is required. 0.4. Related Internet Documents This document discusses applicability of existing mechanisms and potential solutions drafts (listed below) to L1VPN service requirements as summarized in the following draft. o draft-takeda-l1vpn-framework-03.txt (Feb 2005) "Framework for Layer 1 Virtual Private Networks" This draft examines motivations for L1VPNs, summarizes high level (service level) requirements, and describes L1VPN architectural models. Note this document translates the work of ITU-T Study Group 13 Question 11. This document discusses the applicability of the following solution drafts to L1VPN service requirements. o draft-ouldbrahim-ppvpn-gvpn-bgpgmpls-05.txt (May 2004) T.Takeda, et al. Expires August 2005 [Page 2] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 "GVPN Services: Generalized VPN Services using BGP and GMPLS Toolkit" This draft describes a suite of port-based Provider-provisioned VPN services called Generalized VPNs (GVPNs) that uses BGP as a VPN auto-discovery and GMPLS as a signaling mechanism. o draft-ietf-ccamp-gmpls-overlay-05.txt (Oct 2004) "Generalize Multiprotocol Label Switching(GMPLS) User-Network Interface (UNI): Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Support for the Overlay Model" This draft addresses the application of GMPLS to the overlay model. In one section, the draft provides a description of how the overlay model may be used to support VPN connections across a core GMPLS network. Other drafts will be also mentioned when appropriate. Contents 1. Contributors ............................................. 4 2. Terminology .............................................. 4 3. Introduction ............................................. 4 3.1. Existing Solution Drafts ................................. 5 4. General Guideline ........................................ 6 5. Applicability to Management-based Service Model .......... 7 5.1. Overview of the Service Model ............................ 7 5.2. Applicability of Existing Solutions ...................... 7 5.3. Additional Work Area(s) .................................. 7 6. Applicability to Signaling-based Service Model (Overlay Service Model) .......................................... 9 6.1. Overview of the Service Model ............................ 9 6.2. Applicability of Existing Solutions ...................... 9 6.3. Additional Work Area(s) .................................. 10 7. Applicability to Signaling and Routing Service Model ..... 12 7.1. Virtual Node Service Model ............................... 12 7.1.1. Overview of the Service Model ............................ 12 7.1.2. Applicability of Existing Solutions ...................... 12 7.1.3. Additional Work Area(s) .................................. 13 7.2. Virtual Link Service Model ............................... 14 7.2.1. Overview of the Service Model ............................ 14 7.2.2. Applicability of Existing Solutions ...................... 14 7.2.3. Additional Work Area(s) .................................. 14 7.3. Per VPN Peer Service Model ............................... 14 7.3.1. Overview of the Service Model ............................ 15 7.3.2. Applicability of Existing Solutions ...................... 15 7.3.3. Additional Work Area(s) .................................. 15 8. Management Aspect ........................................ 16 8.1. Fault Management ......................................... 16 T.Takeda, et al. Expires August 2005 [Page 3] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 8.2. Configuration Management ................................. 17 8.3. Security Management ...................................... 17 9. Discussion ............................................... 18 10. Security Considerations .................................. 19 11. IANA Considerations ...................................... 19 12. Acknowledgement .......................................... 19 13. Normative References ..................................... 19 14. Informative References ................................... 20 15. Authors' Addresses ....................................... 22 Appendix I: Network Usage of L1VPN Service Models ............... 23 Intellectual Property Considerations ............................ 24 Full Copyright Statement ........................................ 24 1. Contributors The details of this document are the result of contributions from several authors who are listed here in alphabetic order. Contact details for these authors can be found in a separate section near the end of this document. Deborah Brungard (AT&T) Adrian Farrel (Olddog Consulting) Hamid Ould-Brahim (Nortel Networks) Dimitri Papadimitriou (Alcatel) Tomonori Takeda (NTT) 2. Terminology The reader is assumed to be familiar with the terminology in [RFC3031], [RFC3209], [RFC3471], [RFC3473], [GMPLS-RTG], [PPVPN-TERM] and [L1VPN-FW]. 3. Introduction This document shows the applicability of existing Generalized Multiprotocol Label Switching (GMPLS) protocols and mechanisms to Layer 1 Virtual Private Networks (L1VPNs). In addition, this document identifies several areas where additional protocol extensions or modifications are needed to meet L1VPN service requirements. In particular, this document shows section by section (from section 5 to 7) the applicability of GMPLS protocols and mechanisms to each L1VPN service model mentioned in [L1VPN-FW], along with additional work areas needed to fully support the requirements for each service model. Note that management aspects, some of which are common over various service models, are described separately in section 8. Additional information regarding network usage of L1VPN service models is provided in the appendix. T.Takeda, et al. Expires August 2005 [Page 4] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 Note that discussion in this document is limited to areas where GMPLS protocols and mechanisms are relevant. As will be described in this document, support of management-based service model, signaling-based service model and virtual node service model are well covered by existing documents, with minor extensions. Virtual link service model and per VPN peer service model are not explicitly covered by existing documents, but can be realized by extending current GMPLS protocols and mechanisms. Also, as will be described, the following are possible work areas where additional work would be required to fully support the requirements for each L1VPN service model. Some of the requirements are optional therefore the additional work is also optional. Also, some items below may have more than one existing mechanism (with possible extensions). For those items, choosing the minimum set of mechanisms is the required additional work. Commonalities of mechanisms over various service models should be considered. Also, various mechanisms should be coordinated in such a way that services are provided in a fully functional manner. This list of additional work areas will be updated in later versions of this document along with the development of the additional or enhanced requirements and increased understanding of the issues. o MIB module for SPC o Resource management per VPN o Signaling mechanisms o VPN membership information exchange o CE-PE TE link information exchange o Routing representation (how a VPN should be represented in routing, e.g., single area, multi area, multi AS) o Control plane routing (routing information exchange related to control plane topology, per VPN control packet routing) o Signaling and routing for support of per VPN peer service model o Management aspect (fault management, configuration management, security management) A MIB module for possible protocol extensions will also need to be studied. 3.1 Existing Solutions Drafts There are two existing solutions documents that describe how L1VPNs may be constructed using the mechanisms of GMPLS. This document draws on those solutions and explains their applicability and suggests further extensions to make the solutions more closely match the T.Takeda, et al. Expires August 2005 [Page 5] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 framework described in [L1VPN-FW]. o [GVPN] describes a suite of port-based Provider-provisioned VPN services called Generalized VPNs (GVPNs) that uses BGP as a VPN auto-discovery and GMPLS as a signaling mechanism. o [GMPLS-UNI] addresses the application of GMPLS to the overlay model. In one section, the document provides a description of how the overlay model may be used to support VPN connections across a core GMPLS network. 4. General Guideline This section provides general guidelines for L1VPN solutions. Note applicability to specific service models will be separately described in following sections. One important general guideline is that solutions should be incremental. In other words, the same mechanisms should be maximally reused in various service models, and as service models vary and additional functionalities are required, delta functionalities should be added. For example, it is highly desirable that the same signaling protocols are used in both the signaling-based model and the signaling and routing service model, and routing functions are added or enhanced from signaling-based service model to signaling and routing service model. In addition, the following are general guidelines. - Both P and CE devices should be able to use (in most cases) vanilla GMPLS protocols with no specific L1VPN extensions. If Ps and CEs need to be extended for L1VPNs, then backward compatibility should be considered. Details of backward compatibility are for further study. - Solutions should be scalable and manageable (it is desirable that solutions should not require L1VPN state to be maintained on the Ps) - Solutions should be secure. (i.e., providers should be able to screen and protect information based on their operational policies.) - Highly desirable for solutions to provide for the customer and provider a common operational and management perspective in regard to other VPN services, L2 and L3. Note that some deployments may wish to support multiple L1 connection types (such as VC3, VC4, etc.) at the same time. Specific functionalities may need to be considered for these scenarios. This is for further study. T.Takeda, et al. Expires August 2005 [Page 6] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 5. Applicability to Management-based Service Model 5.1. Overview of the Service Model The customer and the provider communicate via a management interface. The provider management system(s) communicate with the PE/P to set up a connection. 5.2. Applicability of Existing Solutions SNMP MIB modules are one way to realize connection setup/deletion/modification from the management system(s). In particular, GMPLS-LSR-STD-MIB [LSR MIB] can control static connections, while GMPLS-TE-STD-MIB [TE MIB] can control signaled connections. As indicated in [L1VPN-FW], the specification of interface(s) between management system(s) (i.e. customer and provider) is out of the scope of this document. 5.3. Additional Work Area(s) The following additional work areas are identified to support the Management-based Service Model. o MIB module for SPC (Soft Permanent Connection) For static connections, there is no required extension to the MIB modules. For signaled connections, MIB modules should be able to inform the ingress and egress PEs which CE-PE TE link should be used. For the egress side, egress control [EGRESS-CONTROL] can be used. For the ingress side, there are two alternatives to do this. Option1: MIB module extension Define a new MIB object to specify the ingress CE-PE TE link to be used. Option2: MIB object usage extension Use the current MIB objects, but extend the way to use them. There are two possible ways to do this. (1) Set mplsTunnelIngressLSRId in mplsTunnelTable, which corresponds to Tunnel Sender Address in the Sender Template object of RSVP-TE, to the CE-PE TE link address. T.Takeda, et al. Expires August 2005 [Page 7] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 (2) Set mplsTunnelHopIpAddr of the first MplsTunnelHopEntry in mplsTunnelHopTable, which corresponds to the first element of ERO of RSVP-TE, to the CE-PE TE link address. It may require to define a new mplsTunnelHopAddrType in mplsTunnelHopTable, which corresponds to a new ERO subobject, in order to give precise meaning. Detailed analysis of option 1 and 2 is for further study. o Resource management per VPN In this type of service model, one optional requirement is resource management for a dedicated Data-Plane (the provider network partitions link resources per VPN for exclusive use by a particular VPN), and resource management for sharing the Data-Plane among a specific set of VPNs (the provider network assigns link resources to a specific set of VPNs). There are two alternatives to do this. Option 1: Policy A simple way to meet this requirement is to implement resource management functionalities as a policy solely in the entity that computes a path. Therefore, no protocol extension is needed. This scheme is especially effective when path computation is done in a centralized manner (e.g., in the management system(s)). Option 2: Routing extension The other alternative is to extend the routing protocol to specify the amount of resources available to each VPN. In this scheme, the PE/P can compute a path in a distributed way, thus this scheme is especially beneficial in the case of dynamic restoration (restoration that does not reserve backup resources in advance). Note that link coloring may be used for this purpose, but this eliminates the opportunity to use link coloring for other purposes (e.g., link coloring within VPNs). Detailed analysis of option 1 and 2 is for further study. o Other considerations When path computation is done in a centralized entity (e.g., management system(s)), it is important that resource information is synchronized between such an entity and the PE/P. T.Takeda, et al. Expires August 2005 [Page 8] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 6. Applicability to Signaling-based Service Model (Overlay Service Model) 6.1. Overview of the Service Model In this type of service model, there is no routing between the CE and the PE. Connections are setup by GMPLS signaling between the CE and the PE, and then across the provider network. A CE may optionally receive a list of TE link addresses to which it can request a VPN connection (overlay extension). 6.2. Applicability of Existing Solutions The following are required in this service model. - VPN membership information exchange: CE-PE TE link address exchange between PEs, along with information associated with a VPN. The TE link addresses may be customer assigned private addresses. - Signaling: CE-CE LSP setup/deletion/modification - Others: Resource management per VPN etc. Additionally, VPN membership information exchange between a CE and PE is required for overlay extension. [GVPN] and [GMPLS-UNI] cover most of the requirements. Specifically, [GVPN] covers VPN membership information exchange by BGP. Customer assigned private addresses are exchanged along with a provider network address (which is reachable in the provider network's routing) and an ID associated with a VPN (i.e., Route Target). This allows PEs to perform address translation/mapping and connectivity restriction. In addition, [GVPN] and [GMPLS-UNI] suggest two signaling mechanisms for VPN connections. o Shuffling [GVPN] Information carried in RSVP messages identifying a LSP (i.e. SESSION and SENDER_TEMPLATE objects) is translated by the ingress and egress PE. There is one end-to-end session (i.e., CE-to-CE). o Nesting [GVPN][GMPLS-UNI][LSP HIER] When Path message arrives at the ingress PE, the ingress PE checks whether there is appropriate PE-to-PE connectivity. If there is not, it initiates a PE-to-PE FA-LSP. On top of this FA-LSP, T.Takeda, et al. Expires August 2005 [Page 9] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 CE-to-CE LSP is set up. There are two sessions (i.e., CE-to-CE, and PE-to-PE). LSP stitching is a particular case of LSP nesting where the properties of LSP segment are such that exactly one end-to-end LSP can be stitched with the LSP segment i.e. the PE-to-PE LSP and the CE-to-CE LSP correspond exactly one to one [STITCHING]. Finally, [GVPN] covers the requirement to exchange membership information between the CE and the PE by BGP for overlay extension. The other possibility is to use IGP based VPN membership information exchange (e.g., similar to as an AS external route, or based on [OSPF-NODE-ADDR], with extensions for VPN applications). This requires the implementation of such IGP. 6.3. Additional Work Area(s) The following additional work areas are identified to support the Signaling-based Service Model. o Signaling mechanisms As described in section 6.1.2, [GMPLS-UNI] and [GVPN] suggest two signaling mechanisms for VPN connections. Option 1: Shuffling In this mechanism, there is no need to set up a PE-to-PE FA-LSP. Though, for this option, objects need to be translated at the ingress and egress PEs. Option 2: Nesting In this mechanism, there is a need to set up a PE-to-PE FA-LSP. For this option, objects need not be translated at the ingress and egress PEs. In the case of nesting, it is necessary to specify an addressing space to exchange signaling messages directly between PEs (i.e., provider addressing space or VPN addressing space). Associated mechanisms may need to be specified as well. Detailed analysis, including under which condition signaling mechanisms (shuffling or nesting) should be used, is for further study. o VPN membership information exchange T.Takeda, et al. Expires August 2005 [Page 10] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 As described in section 6.2, there are two existing mechanisms based on which VPN membership information exchange is realized. Option 1: BGP-based [GVPN] specifies a BGP-based mechanism to realize VPN membership information exchange. There is no additional work required, except for detailed specification of format and encoding. Option 2: IGP-based OSPF allows AS external routes to be advertised. In addition, [OSPF-NODE-ADDR] extends OSPF-TE to advertise a router's local addresses. These mechanisms can be used to advertise CE-PE TE link addresses. In order to support customer assigned private addresses and connectivity restrictions, this mechanism needs to be extended to exchange information similar to an RT (Route Target) and possibly an RD (Route Distinguisher), along with CE-PE TE link addresses. Detailed analysis of options 1 and 2 is for further study. o Resource management per VPN See section 5.2. Note that in option 1 of section 5.2, when path computation is done in a separate entity, the interface for PCE (Path Computation Element) [PCE ARCH] needs to be extended for VPN applications. o CE-PE TE link information exchange In Signaling-based Service Model, it may be useful to consider not only TE link information within the provider network (PE-P, PE-PE TE links), but also remote CE-PE TE link information in path computation. This prevents connection setup failure due to lack of resources of remote CE-PE TE links. Therefore, CE-PE TE link information should be optionally propagated within the provider network to be used for path computation. There are three alternatives for this. Option1: BGP-based [GVPN] describes potential use of BGP for exchanging CE-PE TE link information. Detailed protocol specifications are needed as additional work. Option 2: IGP-based T.Takeda, et al. Expires August 2005 [Page 11] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 The other alternative is to use IGP to advertise CE-PE TE links. Since a CE does not participate in routing protocol exchange with the provider network, TE link information must be properly constructed by only a PE advertising CE-PE TE link information. Option 3: LMP LMP [LMP] can be used to exchange CE-PE TE link information between PEs, with appropriate extensions. Detailed analysis of options 1, 2 and 3 is for further study. o Other considerations Note, there could be a L1VPN solution where connectivity restriction, address translation/mapping etc. are performed not in PEs, but in other entities, such as a centralized server. In this case, the interface between the PE and the other entity may need to be specified. This could utilize existing mechanisms such as COPS or LDAP. Also note that [GVPN] assumes that, on a PE and a CE, control channels are separate for each VPN (i.e., a CE-PE control channel is not shared by multiple VPNs). 7. Applicability to Signaling and Routing Service Model 7.1. Virtual Node Service Model 7.1.1. Overview of the Service Model In this type of service model, there is private routing between the CE and the PE, or to be more precise between the CE routing protocol and the VPN routing protocol instance running on the PE. The provider network is considered as one private node from the customer's perspective. The routing information exchanged between the CE and the PE includes CE-PE TE link information, CE sites, and may include FA-LSPs (connections between CEs (or Cs)), CE sites routing information related to control plane topology. 7.1.2. Applicability of Existing Solutions The followings are required in this service model. - VPN routing: - Signaling: CE-CE LSP setup/deletion modification - Others: Resource management per VPN etc. T.Takeda, et al. Expires August 2005 [Page 12] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 [GVPN] covers most of the requirements. Specifically, [GVPN] handles VPN routing by a per VPN database called the GVSI (Generalized Virtual Switching Instance) in PEs. GVSIs are inter- connected by tunnel based control channels, and routing adjacencies are established between them. BGP is used for auto-discovery of remote GVSI (VPN auto-discovery) in the same VPN. GVSIs advertise VPN routing information by using the same ROUTER_ID to represent the provider network as one node. In addition, [GVPN] supports signaling by nested signaling (as in the case of the Signaling-based Service Model). There are other ways to realize VPN auto-discovery. One such way is to use an IGP-based mechanism (e.g., based on [OSPF-CAP] or [OSPF-NODE-ADDR] with extensions). Other possibilities are to use a server based approach (e.g., DNS, based on [DNS DISCOVERY], RADIUS, based on [RADIUS DISCOVERY]) and multicast (e.g., based on [RFC2917]). 7.1.3. Additional Work Area(s) The following additional work areas are identified to support the Virtual Node Service Model. o Routing representation In the Virtual Node Service Model, one item that should be considered is how to represent a VPN in routing (e.g., single IGP area, multiple IGP areas, multiple ASes). Depending on the routing representation, details may differ (e.g., use of auto-discovery). This requires further discussion. o Resource management per VPN See section 6.1.3 o Control plane routing The provider network must be carefully designed whether to allow routing information related to control plane topology of the provider network to be leaked to the CE. If routing information related to control plane topology of the provider network is leaked to the CE, this routing information may need to be assigned private addresses. When the provider network supports routing information related to control plane topology of CE sites to be exchanged between the CE T.Takeda, et al. Expires August 2005 [Page 13] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 and the PE, and allows control packets to be transferred between CE sites (e.g., BGP packets), the provider network must be carefully designed how to route per VPN control packets received from the CE. 7.2. Virtual Link Service Model 7.2.1. Overview of the Service Model In this type of service model, virtual links are established between PEs. The routing information exchanged between the CE and the PE includes CE-PE TE link, CE sites, virtual links, and may include FA-LSP and CE sites routing information related to control plane topology. 7.2.2. Applicability of Existing Solutions Currently, there is no solution document for this type of service model. However, simple modifications of [GVPN], in addition to enhancements mentioned in section 7.1.3, may realize this type of service model. Modifications could be: - Do NOT modify the ROUTE_ID of the TE link information when advertising a CE-PE TE link to the CE (in the OSPF packet header as well as in the LSA header) - Set up FA-LSPs (GVSI-LSPs in [GVPN] terms) between PEs to construct virtual links, and advertise these FA-LSPs in VPN routing. Note these FA-LSPs (virtual links) may be assigned private addresses, which means customer assigned addresses (or that customers are allowed to configure addresses). This may require extension to current IGP behavior. Note there could be other ways to construct virtual links (e.g., virtual links without actually setting up a FA-LSP [MRN REQ]). 7.2.3. Additional Work Area(s) There is no additional work area beyond the already identified work area for the Virtual Node Service Model mentioned in section 7.1.3. Note that resource management for a dedicated Data-Plane is a mandatory requirement for Virtual Link Service Model. This could be realized by assigning pre-configured FA-LSPs to each VPN routing protocol instance (no protocol extensions needed). Note as in the case of Virtual Node Service Model, depending on routing representation, details may differ. This requires further discussion. 7.3. Per VPN Peer Service Model T.Takeda, et al. Expires August 2005 [Page 14] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 7.3.1. Overview of the Service Model In this type of service model, the provider partitions TE links within the provider network per VPN. The routing information exchanged between the CE and the PE includes CE-PE TE links, CE sites, as well as partitioned portions of the provider network, and may include FA-LSPs and CE sites routing information related to control plane topology. Note that PEs may advertise abstracted routing information of the provider network to CEs. Note scalability must be carefully considered for advertising provider network routing information to the CE [INTER-DOMAIN FW]. 7.3.2. Applicability of Existing Solutions Currently, there is no solution document for this type of service model. However, [GVPN] provides several functionalities to meet this type of service model, as described in section 7.1.2. One way is to extend mechanisms for the Virtual Node Service Model. The other way is to extend mechanisms for the Virtual Link Service Model. 7.3.3. Additional Work Area(s) As described in section 7.3.2, there are two approaches for this type of service model. Note as in the case of Virtual Node Service Mode, depending on routing construction, details may differ. This requires further discussion. o Signaling and routing for support of per VPN peer service model. Option 1: Virtual node-based Per VPN Peer Service Model may be realized by extending virtual node technique so that PEs selectively advertise provider internal TE links to CEs. There are several extensions needed for this. - Topology filtering The PE must choose TE links that are assigned to a specific VPN, and then advertise these TE links to a specific set of CEs corresponding to that VPN. - Topology abstraction The PE may abstract routing information of the provider network, T.Takeda, et al. Expires August 2005 [Page 15] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 and then advertise abstracted topology information to the CE. It means that the PE may construct a TE link where a direct physical link does not exit, or the PE may construct a single node to represent multiple nodes and TE links. Note scalability must be carefully considered [INTER-DOMAIN FW]. - ERO/RRO expansion/modification The CE may specify ERO with abstracted topology. The provider network must expand this ERO to match the provider network topology. Note this must be done even if strict route is specified in ERO passed from the CE. At the same time, when RRO is requested, the RRO passed to the CE must be either edited to match the abstracted topology, or removed. - Private address The provider network may support private addresses for routing information provided to the customer. This means that the customer is able to assign private addresses to a partitioned portion of the TE links within the provider network. o Option 2: Virtual link-based Per VPN Peer Service Model may be realized by extending virtual link technique so that not only PEs but also Ps, that contain end point of virtual links in the abstracted topology, contain VPN routing instance. There may be no additional protocol extensions needed from the Virtual Link Service Model. Detailed analysis of options 1 and 2 is for further study. 8. Management Aspect 8.1. Fault Management The provider network may support various recovery techniques mentioned in [P&R TERM]. The customer may be allowed to specify the desired level of recovery in connection setup requests. The provider network may constitute a recovery domain (PE-PE recovery). Following aspects need to be considered relative to L1VPNs. o Shared recovery When the provider network supports shared recovery (e.g., shared T.Takeda, et al. Expires August 2005 [Page 16] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 mesh restoration), the provider network may be able to support shared recovery only within the same VPN and/or shared recovery among multiple VPNs. The default mode is to be specified. If the provider network supports both, the provider network must provide configuration tools for operators. o Extra traffic GMPLS recovery mechanisms support extra traffic. Extra traffic allows supporting pre-emptible traffic on recovery resources when these resources are not being used for the recovery of normal traffic [P&R TERM]. When the provider network supports extra traffic, the provider network may be able to support extra traffic only within the same VPN and/or extra traffic among multiple VPNs. The default mode is to be specified. If the provider network supports both, the provider network must provide configuration tools for operators. 8.2. Configuration Management Some VPN specific configuration aspects must be considered, such as: o Configuration of resource management per VPN Physical link resources may be dedicated, shared by a specific set of VPNs, or shared by any VPNs. The provider network must provide configuration tools for resource management per VPN. o Configuration of virtual links For virtual link service model and per VPN peer service model, the provider network must provide configuration tools for operators. o Configuration of service model for each VPN When the provider network supports multiple service models, the provider network must provide configuration tools for operators. 8.3. Security Management o CE-PE security When a CE-PE control channel is physically shared by multiple VPNs, security mechanisms need to be applied for data integrity and T.Takeda, et al. Expires August 2005 [Page 17] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 confidentiality of control messages exchanged. Furthermore, when a CE-PE control channel is dynamically setup, authentication need to be performed. The mechanisms to achieve these include IPsec. Details for additional work areas are for further study. 9. Discussion This section summarizes items for which existing solutions may need to be extended in order to fulfill the full set of L1VPN service model functionalities. Note that several of these items are in support of optional features. For the management-based service model, signaling-based service model and virtual node service model, the existing solutions can be applied with few extensions. As described in section 7.2.2 and 7.2.3, there are no existing solutions to support the virtual link service model and per VPN peer service model. For virtual link service model, however, minor extensions from existing solutions are expected to meet the requirements. Note the list of additional work areas will be updated in later versions of this document with the development of additional or enhanced requirements and understanding of the issues. o MIB module for SPC - Optional, but highly required for management-based service model - Two alternatives (MIB module extension or MIB object usage extension) - Impact: MIB module or none o Resource management per VPN - Optional requirement for management-based, signaling-based and virtual node service models - Mandatory requirement for virtual link and per VPN peer service models (support of resource management for dedicated Data-Plane) - Two alternatives (policy or routing extension) - For virtual link service model, can be realized by no protocol extensions (assign pre-configured FA-LSP to each VPN routing instance). - Impact: None or IGP o Signaling mechanisms - Mandatory requirement for signaling-based service model and signaling and routing service model - Two alternatives (shuffling or nesting) - Impact: Signaling T.Takeda, et al. Expires August 2005 [Page 18] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 o VPN membership information exchange - Mandatory requirement for signaling-based service model - Two alternatives (BGP or IGP) - Impact: BGP or IGP o CE-PE TE link information exchange - Optional requirement for signaling-based service model - Three alternatives (BGP or IGP or LMP) - Impact: BGP or IGP or LMP o Routing representation - One building block for signaling and routing service model - Further discussion required (single area, multi areas, multi ASes, etc.) - Impact: Details to be studied (routing, use of auto-discovery, etc.) o Control plane routing - Optional requirement for signaling and routing service model - Impact: Routing o Signaling and routing for support of per VPN peer service model - Two options (virtual node-based, virtual link-based) - Impact: Routing, signaling (details to be studied) o Management aspects - Default mode to be specified for shared recovery and extra traffic - Support of configuration tools mandatory for fault management and configuration management - Details for security management to be studied - Impact: mostly on operational tools (impacts on protocols to be studied) 10. Security Considerations Section 8.3 describes some of security considerations. Details are for further study. 11. IANA Considerations TBD 12. Acknowledgement We would like to thank Marco Carugi, Ichiro Inoue and Takumi Ohba for their useful comments and suggestions. 13. Normative References T.Takeda, et al. Expires August 2005 [Page 19] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 [RFC3668] Bradner, S., "Intellectual Property Rights in IETF Technology", BCP 79, RFC 3668, February 2004. [L1VPN-FW] Takeda, T., Editor "Framework for Layer 1 Virtual Private Networks", draft-takeda-l1vpn-framework, work in progress. 14. Informative References For information on the availability of this document, please see http://www.itu.int. [Y.1312] Y.1312 - Layer 1 Virtual Private Network Generic requirements and architecture elements, ITU-T Recommendation, September 2003. For information on the availability of this document, please see http://www.itu.int. [Y.1313] Y.1313 - Layer 1 Virtual Private Network service and network architectures, ITU-T Recommendation, July 2004. [GMPLS-UNI] Swallow, G., et al., "Generalize Multiprotocol Label Switching(GMPLS) User-Network Interface (UNI): Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Support for the Overlay Model", draft-ietf-ccamp-gmpls-overlay, work in progress. [GVPN] Ould-Brahim, H., and Rekhter, Y. (editors), "GVPN Services: Generalized VPN Services using BGP and GMPLS Toolkit", draft-ouldbrahim-ppvpn-gvpn- bgpgmpls, work in progress. [LSP HIER] Kompella, K., Rekhter, Y., "LSP Hierarchy with Generalized MPLS TE", draft-ietf-mpls-lsp- hierarchy, work in progress. [STITCHING] Ayyangar, A. (editor), "LSP Stitching with Generalized MPLS TE", draft-ayyangar-ccamp-lsp- stitching, work in progress. [INTER-DOMAIN FW] Farrel, A., et al., "A Framework for Inter-Domain MPLS Traffic Engineering", draft-ietf-ccamp- inter-domain-framework, work in progress. [P&R TERM] Mannie, E., and Papadimitriou, D. (editors), T.Takeda, et al. Expires August 2005 [Page 20] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 "Recovery (Protection and Restoration) Terminology for Generalized Multi-Protocol Label Switching (GMPLS)", draft-ietf-ccamp-gmpls-recovery- terminology, work in progress. [LSR MIB] Nadeau, T., et al., "Generalized Multiprotocol Label Switching (GMPLS) Label Switching Router (LSR) Management Information Base", draft-ietf- ccamp-gmpls-lsr-mib, work in progress. [TE MIB] Nadeau, T., et al., "Generalized Multiprotocol Label Switching (GMPLS) Traffic Engineering Management Information Base", draft-ietf-ccamp- gmpls-te-mib, work in progress. [RFC3031] Rosen, E., Viswanathan, A. and R. Callon, "Multiprotocol label switching Architecture", RFC 3031, January 2001. [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V. and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC3471] Berger, L., Editor, "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", RFC 3471, January 2003. [RFC3473] Berger, L., Editor "Generalized Multi-Protocol Label Switching (GMPLS) Signaling - Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [GMPLS-RTG] Kompella, K., et al., "Routing Extensions in Support of Generalized MPLS", draft-ietf-ccamp- gmpls-routing, work in progress. [EGRESS CONTROL] Berger, L., "GMPLS Signaling Procedure For Egress Control", draft-ietf-ccamp-gmpls-egress-control, work in progress. [OSPF-CAP] Vesseur, J.P., et al., "Extensions to OSPF for Advertising Optional Router Capabilities", draft-ietf-ospf-cap, work in progress. [OSPF-NODE-ADDR] Aggarwal, R., Kompella, K., "Advertising a Router's Local Addresses in OSPF TE Extensions", draft-ietf-ospf-te-node-addr, work in progress. T.Takeda, et al. Expires August 2005 [Page 21] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 [LMP] Lang, J., "Link Management Protocol (LMP)", draft-ietf-ccamp-lmp, work in progress. [DNS DISCOVERY] Squire, M., et al., "Using DNS for VPN Discovery", draft-luciani-ppvpn-vpn-discovery (Expired). [RADIUS DISCOVERY] Weber, G., Editor "Using RADIUS for PE-Based VPN Discovery", draft-ietf-l2vpn-radius-pe-discovery (Expired). [RFC2917] Muthukrishnan, K., Malis, A., " A Core MPLS IP VPN Architecture", RFC2917, September 2000. [PPVPN-TERM] Andersson, L., and Madsen, T., "Provider Provisioned VPN terminology", draft-ietf-l3vpn-ppvpn-terminology, work in progress. [PCE ARCH] Ash, J., et al., "Path Computation Element (PCE) Architecture", draft-ash-pce-architecture, work in progress. [MRN REQ] Shiomoto, K., et al., "Requirements for GMPLS- based multi-region and multi-layer networks", draft-shiomoto-ccamp-gmpls-mrn-reqs, work in progress. 15. Authors' Addresses Deborah Brungard (AT&T) Rm. D1-3C22 - 200 S. Laurel Ave. Middletown, NJ 07748, USA Phone: +1 732 4201573 Email: dbrungard@att.com Adrian Farrel Old Dog Consulting Phone: +44 (0) 1978 860944 Email: adrian@olddog.co.uk Hamid Ould-Brahim Nortel Networks P O Box 3511 Station C Ottawa, ON K1Y 4H7 Canada Phone: +1 (613) 765 3418 Email: hbrahim@nortelnetworks.com Dimitri Papadimitriou (Alcatel) Francis Wellensplein 1, T.Takeda, et al. Expires August 2005 [Page 22] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 B-2018 Antwerpen, Belgium Phone: +32 3 2408491 Email: dimitri.papadimitriou@alcatel.be Tomonori Takeda NTT Network Service Systems Laboratories, NTT Corporation 3-9-11, Midori-Cho Musashino-Shi, Tokyo 180-8585 Japan Phone: +81 422 59 7434 Email : takeda.tomonori@lab.ntt.co.jp Appendix I: Network Usage of L1VPN Service Models This appendix provides additional information concerning network usage of the L1VPN service models. o Management-based service model In this model, the provider network can support non-GMPLS capable CEs. Therefore, this model is best suited when customer networks are non-GMPLS, e.g., legacy SONET/SDH and IP/MPLS networks. It is expected that the provider network requires no or minimal GMPLS extensions for L1VPN specific functions. o Signaling-based service model In this model, by implementing GMPLS signaling functions in CEs, the customer can request an LSP setup/deletion/modification to the provider by signaling. Customers will receive rapid failure notifications of an LSP by using notification mechanisms available in GMPLS RSVP-TE. There are some L1VPN specific extensions required within the provider network. Concerning customer network routing information, since only CE-PE TE link addresses are contained within the provider network, it is expected that there is less concern on scalability. Trust relationships between the customer and the provider may need to be carefully considered. o Signaling and routing service model In this model, a customer can seamlessly operate its VPN using end-to-end GMPLS. Therefore, this model is best suited when customer networks are operated by GMPLS. For the service model where the provider network's routing information is not provided to customers (i.e., Virtual Node Service Model), a customer can outsource routing complexity within T.Takeda, et al. Expires August 2005 [Page 23] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 the provider network to the provider. On the other hand, in the service model where the provider network routing information is provided to customers (i.e., Virtual Link Service Model and Per VPN Peer Service Model), customers play more of a role. For example, by allowing customers to assign SRLG IDs for virtual links, customers can compute and set up end to end disjoint LSPs in their VPN. There are some L1VPN specific extensions required within the provider network. Concerning customer network routing information, since the customer network routing information is contained within the provider network, scalability must be carefully considered. Trust relationships between the customer and the provider may need to be carefully considered as well. Intellectual Property Considerations The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Full Copyright Statement Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE T.Takeda, et al. Expires August 2005 [Page 24] Internet Draft draft-takeda-l1vpn-applicability-02.txt February 2005 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. T.Takeda, et al. Expires August 2005 [Page 25]