Network Working Group K. Kumaki, Ed. Internet Draft KDDI R&D Labs Intended Status: Informational R. Zhang Created: July 31, 2009 BT Expires: January 1, 2010 Y. Kamite NTT Communications Requirements for supporting Customer RSVP and RSVP-TE over a BGP/MPLS IP-VPN draft-ietf-l3vpn-e2e-rsvp-te-reqts-04.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. 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. This Internet-Draft will expire on January 1, 2010. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. K.Kumaki, et al. [Page 1] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Abstract Today, customers expect to run triple play services through BGP/MPLS IP-VPNs. Some Service Providers will deploy services that request QoS guarantees from a local CE to a remote CE across the network. As a result, the application (e.g., voice, video, bandwidth-guaranteed data pipe, etc.) requirements for end-to-end QOS and reserving adequate bandwidth continue to increase. Service Providers can use both MPLS and an MPLS-TE LSP to meet the service objectives. This document describes service provider requirements for supporting customer RSVP and RSVP-TE over a BGP/MPLS IP-VPN. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. K.Kumaki, et al. [Page 2] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 Table of Contents 1. Introduction..................................................4 2. Terminology...................................................5 3. Problem Statement.............................................5 4. Application Scenarios.........................................7 4.1 Scenario I: Fast Recovery over BGP/MPLS IP-VPN............7 4.2 Scenario II: Strict C-TE LSP QoS Guarantees...............8 4.3 Scenario III: Load Balance of CE-to-CE Traffic............9 4.4 Scenario IV: RSVP Aggregation over MPLS TE Tunnels........11 4.5 Scenario V: RSVP over Non-TE LSP..........................11 4.6 Scenario VI: RSVP-TE over Non-TE LSP......................12 5. Detailed Requirements for C-TE LSPs Model.....................13 5.1 Selective P-TE LSPs......................................13 5.2 Graceful Restart Support for C-TE LSPs...................13 5.3 Rerouting Support for C-TE LSPs..........................13 5.4 FRR Support for C-TE LSPs................................13 5.5 Admission Control Support on P-TE LSP Head-Ends..........14 5.6 Admission Control Support for C-TE LSPs in LDP-based Core Networks......................................................14 5.7 Policy Control Support for C-TE LSPs.....................15 5.8 PCE Features Support for C-TE LSPs.......................15 5.9 Diversely Routed C-TE LSPs Support.......................15 5.10 Optimal Path Support for C-TE LSPs.......................16 5.11 Reoptimization Support for C-TE LSPs.....................16 5.12 DS-TE Support for C-TE LSPs..............................16 6. Detailed Requirements for C-RSVP Paths Model..................16 6.1 Admission Control between PE-CE for C-RSVP Paths..........16 6.2 Aggregation of C-RSVP Paths by P-TE LSPs..................17 6.3 Non-TE LSPs support for C-RSVP Paths......................17 6.4 Transparency of C-RSVP Paths..............................17 7. Common Detailed Requirements for Two Models...................17 7.1 CE-PE Routing............................................17 7.2 Complexity and Risks.....................................17 7.3 Backward Compatibility...................................18 7.4 Scalability Considerations...............................18 7.5 Performance Considerations...............................18 7.6 Management Considerations................................18 8. Security Considerations.......................................19 9. IANA Considerations...........................................20 10. References...................................................20 10.1 Normative References.....................................20 10.2 Informative References...................................21 11. Acknowledgments..............................................21 12. Author's Addresses...........................................21 Appendix A. Reference Model......................................22 A.1 End-to-End C-RSVP Path Model..............................22 A.2 End-to-End C-TE LSP Model.................................23 K.Kumaki, et al. [Page 3] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 1. Introduction Some Service Providers want to build a service which guarantees QoS and bandwidth from a local CE to a remote CE through the network. A CE includes network client equipment owned and operated by the service provider. However, the CE may not be part of the MPLS provider network. Today, customers expect to run triple play services through BGP/MPLS IP-VPNs [RFC4364]. As these services evolve, the requirements for end-to-end QoS to meet the application requirements also continue to grow. Depending on the application (e.g., voice, video, bandwidth-guaranteed data pipe, etc.), native IP using RSVP and/or an end-to-end constrained MPLS-TE Label Switched Path (LSP) may be required. The RSVP path may be used to provide QoS guarantees and reserve adequate bandwidth for the data. An end-to-end MPLS-TE LSP may also be used to guarantee bandwidth, and provide extended functionality like MPLS fast reroute (FRR) [RFC4090] for maintaining service continuity around node and link, including CE- PE link, failures. It should be noted that an RSVP session between two CEs may also be mapped and tunneled into an MPLS-TE LSP across an MPLS provider network. A number of advantages exist for deploying the model previously mentioned. The first is that customers can use these network services whilst being able to use both private addresses and global addresses. The second advantage is that traffic is tunneled through the Service Provider backbone, so that customer traffic and route confidentiality is maintained. This document defines a reference model, example application scenarios and detailed requirements for a solution supporting customer RSVP and RSVP-TE over a BGP/MPLS IP-VPN. Specification for a solution is out of scope in this document. K.Kumaki, et al. [Page 4] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 2. Terminology This document uses BGP/MPLS IP VPN terminology defined in [RFC4364]. The document also uses Path Computation Element terms which are defined in [RFC4655]. TE LSP: Traffic Engineering Label Switched Path MPLS TE LSP: Multi Protocol Label Switching TE LSP C-RSVP path: Customer RSVP path: a native RSVP path with bandwidth reservation of X for customers C-TE LSP: Customer Traffic Engineering Label Switched Path: an end-to-end MPLS TE LSP for customers P-TE LSP: Provider Traffic Engineering Label Switched Path: a transport TE LSP between two PEs Head-end LSR: ingress LSR Tail-end LSR: egress LSR LSR: Label Switched Router 3. Problem Statement Service Providers want to deliver triple play services with QOS guarantees to their customers. Various techniques are available to achieve this. Some Service Providers will wish to offer advanced services using RSVP signaling for native IP flows C-RSVP) or RSVP- TE signaling for Customer TE LSPs (C-TE LSPs) over BGP/MPLS IP- VPNs. The following examples outline each method: A C-RSVP path with bandwidth reservation of X can be used to transport voice. In order to achieve sub-50msec recovery during link/node/SRLG failure and to provide strict QoS guarantees, a C- TE LSP with bandwidth X between data centers or customer sites can be used to carry voice and video traffic. Thus, service providers or customers can choose a C-RSVP path or a C-TE LSP to meet their requirements. K.Kumaki, et al. [Page 5] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 When service providers offer a C-RSVP path between hosts or CEs over BGP/MPLS IP-VPNs, the CE/host requests an end-to-end C-RSVP path with bandwidth reservation of X to the remote CE/host. However, if a C- RSVP signaling is to send within VPN, the service provider network will face scalability issues. Therefore, in order to solve scalability issues, multiple C-RSVP reservations can be aggregated at PE, where a P-TE LSP head-end can perform admission control using the aggregated C-RSVP reservations. The method that is described in RFC4804 can be considered as a useful approach. In this case, a reservation request from within the context of a VRF can get aggregated onto a P-TE LSP. The P-TE LSP can be pre-established, resized based on the request, or triggered by the request. Service providers, however, cannot provide a C-RSVP path over VRF instance as defined in RFC4364. The current BGP/MPLS IP-VPN architecture also does not support an RSVP instance running in the context of a VRF to process RSVP messages and integrated services (int-serv) [RFC1633][RFC2210]. One of solutions is described in [RSVP-L3VPN]. If service providers offer a C-TE LSP from CE to CE over BGP/MPLS IP- VPN, they require that a MPLS TE LSP from a local CE to a remote CE be established. However, if a C-TE LSP signaling is to send within VPN, the service provider network may face the following scalability issues: - A C-TE LSP can be aggregated by a P-TE LSP at PE. (i.e. hierarchical LSPs) In this case, only PEs maintain state about customer RSVP-TE sessions. - A C-TE LSP cannot be aggregated by a P-TE LSP at PE depending on some policies. (i.e. contiguous LSPs) In this case, both Ps and PEs maintain state about customer RSVP sessions. - A C-TE LSP can be aggregated by non-TE LSP (i.e. LDP). In this case, only PEs maintain state about customer RSVP-TE sessions. Note that there it is assumed their always enough bandwidth available in service provider core network Furthermore, if service providers provide the C-TE LSP over a BGP/MPLS IP-VPN, they currently cannot provide it over VRF instance as defined in RFC4364. Specifically the current BGP/MPLS IP-VPN architecture does not support an RSVP-TE instance running in the context of a VRF to process RSVP messages and trigger the establishment of the C-TE LSP over the service provider core network If every C-TE LSP is to trigger the establishment or resizing of a P- TE LSP, the service provider network will also face scalability issues that arise from maintaining a large number of P-TE LSPs and/or dynamic signaling of these P-TE LSPs. Section 8.4, Scalability Considerations, of this document provides detailed scalability requirements. K.Kumaki, et al. [Page 6] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 Two different models are described above. The differences between C- RSVP paths and C-TE LSPs are as follows: - C-RSVP path model: data packets among CEs are forwarded by "native IP packets" (i.e. not labeled packets). - C-TE LSP model: data packets among CEs are forwarded by "labeled IP packets". Depending on the service level and the need to meet specific requirements, service providers should be able to choose P-TE LSPs or non-TE LSPs in the backbone network. Selection may be dependent on the Service Providers policy and node capability to support the mechanisms described. The following items are required selectively to support C-RSVP paths and C-TE LSPs over BGP/MPLS IP-VPNs based on the service level. For example, some service providers need all of the following items to provide a service. Some service providers need some of them to provide a service. It depends on a service level and a policy of service providers. Detailed requirements are described in sections 6, 7 and 8. - C-RSVP path QoS guarantees. - Fast recovery over BGP/MPLS IP-VPN to protect traffic for C-TE LSP against CE-PE link failure and PE node failure. - Strict C-TE LSP bandwidth and QoS guarantees. - Resource optimization for C-RSVP paths and C-TE LSPs. - Scalability for C-RSVP paths and C-TE LSPs. 4. Application Scenarios The following sections present a few application scenarios for C-RSVP paths and C-TE LSPs in BGP/MPLS IP-VPN environments. Appendix A. (Reference Model), describes a C-RSVP path, a C-TE LSP and a P-TE LSP. In all scenarios it is the responsibility of the service provider to ensure that enough bandwidth is available to meet the customers application requirements. 4.1 Scenario I: Fast Recovery over BGP/MPLS IP-VPN In this scenario, as shown in figure 1, a customer uses a VoIP application between its sites (i.e., between CE1 and CE2). H0 and H1 are voice equipment. In this case, the customer establishes C-TE LSP1 as a primary path and C-TE LSP2 as a backup path. If the link between PE1 and CE1 or the node PE1 fails, C-TE LSP1 needs C-TE LSP2 as a path protection. K.Kumaki, et al. [Page 7] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 C-TE LSP1 <----------------------------------------------> P-TE LSP1 <---------------------------> ............. ............. . --- --- . --- --- --- --- . --- --- . .|H0 | |CE1|-----|PE1|----|P1 |-----|P2 |----|PE2|-----|CE2| |H1 |. . --- --- . --- --- --- --- . --- --- . .........|... --- --- --- --- ...|......... +-------|PE3|----|P3 |-----|P4 |----|PE4|-------+ --- --- --- --- <---------------------------> P-TE LSP2 <----------------------------------------------> C-TE LSP2 <--customer--> <--------BGP/MPLS IP-VPN-------> <--customer-> network network Figure 1 Scenario I 4.2 Scenario II: Strict C-TE LSP QoS Guarantees In this scenario, as shown in figure 2, a service provider B transports voice and video traffic between its sites (i.e., between CE1 and CE2). In this case, service provider B establishes C-TE LSP1 with preemption priority 0 and bandwidth 100Mbps for voice traffic, and C- TE LSP2 with preemption priority 1 and bandwidth 200Mbps for unicast video traffic. On the other hand, service provider A also pre- establishes P-TE LSP1 with preemption priority 0 and bandwidth 1Gbps for voice traffic, and P-TE LSP2 with preemption priority 1 and bandwidth 2Gbps for video traffic. These P-TE LSP1 and P-TE LSP2 should support DS-TE. [RFC4124] PE1 and PE3 should choose an appropriate P-TE LSP based on preemption priority. In this case, C-TE LSP1 must be associated with P-TE LSP1 at PE1 and C-TE LSP2 must be associated with P-TE LSP2 at PE3. Furthermore, PE1 and PE3 head-ends should control the bandwidth of C- TE LSPs. In this case, PE1 and PE3 can choose C-TE LSPs by the amount of max available bandwidth for each P-TE LSP, respectively. K.Kumaki, et al. [Page 8] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 C-TE LSP1 <----------------------------------------------> P-TE LSP1 <---------------------------> ............. ............. . --- --- . --- --- --- --- . --- --- . .|CE0| |CE1|-----|PE1|----|P1 |-----|P2 |----|PE2|-----|CE2| |CE3|. . --- --- . --- --- --- --- . --- --- . .........|... --- --- --- --- ...|......... +-------|PE3|----|P3 |-----|P4 |----|PE4|-------+ --- --- --- --- <---------------------------> P-TE LSP2 <----------------------------------------------> C-TE LSP2 <---SP B----> <--------BGP/MPLS IP-VPN-------> <---SP B---> network SP A network network Figure 2 Scenario II Its possible that the customer and service provider have differing preemption priorities. In this case then the PE policy will overide the customers. In the case that service provider does not support premption priorities then priorities should be ignored. 4.3 Scenario III: Load Balance of CE-to-CE Traffic In this scenario, as shown in figure 5, service provider C uses voice and video traffic between its sites (i.e., between CE0 and CE5/CE7, between CE2 and CE5/CE7, between CE5 and CE0/CE2, and between CE7 and CE0/CE2). H0 and H1 are voice and video equipment. In this case, service provider C establishes C-TE LSP1, C-TE LSP3, C- TE LSP5 and C-TE LSP7 with preemption priority 0 and bandwidth 100Mbps for voice traffic, and establishes C-TE LSP2, C-TE LSP4, C-TE LSP6 and C-TE LSP8 with preemption priority 1 and bandwidth 200Mbps for video traffic. On the other hand, service provider A also pre- establishes P-TE LSP1 and P-TE LSP3 with preemption priority 0 and bandwidth 1Gbps for voice traffic, and P-TE LSP2 and P-TE LSP4 with preemption priority 1 and bandwidth 2Gbps for video traffic. These P- TE LSP1, P-TE LSP2, P-TE LSP3 and P-TE LSP4 should support DS-TE. [RFC4124] All PEs should choose an appropriate P-TE LSP based on preemption priority. To minimize the traffic disruption due to a single network failure, diversely routed C-TE LSPs are established. In this case, FRR [RFC4090] is not necessarily required. Also, unconstrained TE LSPs (i.e., C-TE LSPs/P-TE LSPs with 0 bandwidth) [RFC5330] are applicable to this scenario. K.Kumaki, et al. [Page 9] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 Furthermore, load balancing for a communication between H0 and H1 can be done by setting up full mesh C-TE LSPs between CE0/CE2 and CE5/CE7. C-TE LSP1(P=0),2(P=1) (CE0->CE1->...->CE4->CE5) (CE0<-CE1<-...<-CE4<-CE5) <--------------------------------------------------> C-TE LSP3(P=0),4(P=1) (CE2->CE1->...->CE4->CE7) (CE2<-CE1<-...<-CE4<-CE7) <--------------------------------------------------> P-TE LSP1 (p=0) <-----------------------> P-TE LSP2 (p=1) <-----------------------> .................. .................. . --- --- . --- --- --- --- . --- --- . . |CE0|-|CE1|---|PE1|---|P1 |---|P2 |---|PE2|---|CE4|-|CE5| . . --- /--- --- . --- --- --- --- . --- ---\ --- . .|H0 | + . + . + |H1 |. . --- \--- --- . --- --- --- --- . --- ---/ --- . . |CE2|-|CE3|---|PE3|---|P3 |---|P4 |---|PE4|---|CE6|-|CE7| . . --- --- . --- --- --- --- . --- --- . .................. .................. <-----------------------> P-TE LSP3 (p=0) <-----------------------> P-TE LSP4 (p=1) <--------------------------------------------------> C-TE LSP5(P=0),6(P=1) (CE0->CE3->...->CE6->CE5) (CE0<-CE3<-...<-CE6<-CE5) <--------------------------------------------------> C-TE LSP7(P=0),8(P=1) (CE2->CE3->...->CE6->CE7) (CE2<-CE3<-...<-CE6<-CE7) <-----SP C-----> <--------BGP/MPLS IP-VPN-------> <-----SP C-----> network SP A network network Figure 5 Scenario III K.Kumaki, et al. [Page 10] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 4.4 Scenario IV: RSVP Aggregation over MPLS TE Tunnels In this scenario, as shown in figure 6, the customer has two hosts connecting off CE1 and CE2 respectively. CE1 and CE2 are connected to PE1 and PE2, respectively, within a VRF instance belonging to the same VPN. The requesting host (H1) may request to H2 an RSVP path with bandwidth reservation of X. This reservation request from within the context of VRF will get aggregated onto a pre-established P-TE/DS-TE LSP based upon procedures similar to [RFC4804]. As in the case of [RFC4804], there may be multiple P-TE LSPs belonging to different DS-TE class-types. Local policies can be implemented to map the incoming RSVP path request from H1 to the P-TE LSP with the appropriate class-type. Please note that the e2e RSVP path request may also be initiated by the CE devices themselves. C-RSVP path <----------------------------------------------> P-TE LSP <---------------------------> ............. ............. . --- --- . --- --- --- --- . --- --- . .|H1 | |CE1|-----|PE1|----|P1 |-----|P2 |----|PE2|-----|CE2| |H2 |. . --- --- . --- --- --- --- . --- --- . ............. ............. ^ ^ | | VRF instance VRF instance <--customer--> <--------BGP/MPLS IP-VPN-------> <--customer-> network network Figure 6 Scenario IV 4.5 Scenario V: RSVP over Non-TE LSP In this scenario, as shown in figure 7, a customer has two hosts connecting off CE1 and CE2, respectively. CE1 and CE2 are connected to PE1 and PE2, respectively, within a VRF instance belonging to the same VPN. The requesting host (H1) may request to H2 an RSVP path with bandwidth reservation of X. In this case, a non-TE LSP (i.e. LDP etc) is provided between PEs and has LDP which supports MPLS diffserv [RFC3270]. Note that this only provides Diffserv and not bandwidth reservation as is done with RSVP-TE. Local policies can be implemented to map customer's reserved flow to the LSP with the appropriate EXP at PE1. K.Kumaki, et al. [Page 11] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 C-RSVP path <----------------------------------------------> Non-TE LSP <---------------------------> ............. ............. . --- --- . --- --- --- --- . --- --- . .|H1 | |CE1|-----|PE1|----|P1 |-----|P2 |----|PE2|-----|CE2| |H2 |. . --- --- . --- --- --- --- . --- --- . ............. ............. ^ ^ | | VRF instance VRF instance <--customer--> <--------BGP/MPLS IP-VPN-------> <--customer-> network network Figure 7 Scenario V 4.6 Scenario VI: RSVP-TE over Non-TE LSP In this scenario, as shown in figure 8, a customer uses a VoIP application between its sites (i.e., between CE1 and CE2). H0 and H1 are voice equipment. In this case, a non-TE LSP means LDP and the customer establishes C-TE LSP1 as a primary path and C-TE LSP2 as a backup path. If the link between PE1 and CE1 or the node PE1 fails, C-TE LSP1 needs C-TE LSP2 as a path protection. C-TE LSP1 <----------------------------------------------> Non-TE LSP <---------------------------> ............. ............. . --- --- . --- --- --- --- . --- --- . .|H0 | |CE1|-----|PE1|----|P1 |-----|P2 |----|PE2|-----|CE2| |H1 |. . --- --- . --- --- --- --- . --- --- . .........|... --- --- --- --- ...|......... +-------|PE3|----|P3 |-----|P4 |----|PE4|-------+ --- --- --- --- <---------------------------> Non-TE LSP <----------------------------------------------> C-TE LSP2 <--customer--> <--------BGP/MPLS IP-VPN-------> <--customer-> network network Figure 8 Scenario VI K.Kumaki, et al. [Page 12] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 5. Detailed Requirements for C-TE LSPs Model This section describes detailed requirements for C-TE LSPs in BGP/MPLS IP-VPN environments. 5.1 Selective P-TE LSPs The solution MUST provide the ability to decide which P-TE LSP a PE uses for a C-RSVP path and a C-TE LSP. When a PE receives a native RSVP and/or a path messages from a CE, it MUST be able to decide which P-TE LSP it uses. In this case, various kinds of P-TE LSPs exist in service provider network. For example, the PE MUST choose an appropriate P-TE LSP based on local policies such as: 1. preemption priority 2. affinity 3. class-type 4. on the data plane: (DSCP or EXP bits) 5.2 Graceful Restart Support for C-TE LSPs The solution SHOULD support the graceful restart capability, where C- TE LSP traffic continues to be forwarded during a PE graceful restart, Graceful restart mechanisms related to this architecture are described in [RFC3473], [RFC3623] and [RFC4781]. 5.3 Rerouting Support for C-TE LSPs The solution MUST provide rerouting of a C-TE LSP in case of link/node/SRLG failures or preemption. Such rerouting may be controlled by a CE or by a PE depending on the failure. In a dual homed enviroment, the ability to perform rerouting MUST be provided against a CE-PE link failure or a PE failure if another is available between the head-end and the tail-end of the C-TE LSP. 5.4 FRR Support for C-TE LSPs The solution MUST support FRR [RFC4090] features for a C-TE LSP over VRF instance. In BGP/MPLS IP-VPN environments, a C-TE LSP from a CE traverses multiple PEs and Ps, albeit tunneled over a P-TE LSP. In order to avoid PE-CE link/PE node/SRLG failures, a CE (a customer's head-end router) needs to support link protection or node protection. K.Kumaki, et al. [Page 13] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 The following protection MUST be supported: 1. CE-PE link protection 2. PE node protection 3. CE node protection 5.5 Admission Control Support on P-TE LSP Head-Ends The solution MUST support admission control on a P-TE LSP tunnel head-end for C-TE LSPs. C-TE LSPs may potentially try to reserve bandwidth that exceeds the bandwidth of the P-TE LSP. The P-TE LSP tunnel head-end SHOULD control the number of C-TE LSPs and/or the bandwidth of C-TE LSPs. For example, the transport TE LSP head-end SHOULD have a configurable limit on the maximum number of C-TE LSPs that it can admit from a CE. As for the amount of bandwidth that can be reserved by C-TE LSPs there could be two situations: 1. Let the P-TE LSP perform local policy bandwidth admission 2. Set a cap on the amount of CE and VRF bandwidth and have the configuration option to: a. Reserve the minimum of the cap bandwidth or the C-TE LSP bandwidth on the P-TE LSP if the required bandwidth is available b. Reject the C-TE LSP if the required bandwidth by the C-TE LSP is not available 5.6 Admission Control Support for C-TE LSPs in LDP-based Core Networks The solution MUST support admission control for a C-TE LSP at a PE in LDP-based core network. Specifically, PEs MUST have a configurable limit on the maximum amount of bandwidth that can be reserved by C- TE LSPs per a vrf instance (i.e. per a customer). Also, a PE SHOULD have a configurable limit on the total amount of bandwidth that can be reserved by C-TE LSPs between PEs. K.Kumaki, et al. [Page 14] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 5.7 Policy Control Support for C-TE LSPs The solution MUST support policy control for a C-TE LSP at a PE. The PE MUST be able to perform at least the following: 1. Limit the rate of RSVP-TE messages per PE-CE link 2. Accept and map or reject requests for a given affinity 3. Accept and map or reject requests with a specified setup and/or pre-emption priorities. 4. Accept or reject requests for fast reroutes 5. Neglect the requested setup and/or pre-emption priorities and select a P-TE LSP based on a local policy that applies to the CE-PE link or VRF. 6. Ignore the requested affinity and select a P-TE LSP based on a local policy that applies to the CE-PE link or VRF. 7. Perform mapping in data plane between customer exp bits and transport P-TE LSP exp bits, as signaled per [RFC3270]. 5.8 PCE Features Support for C-TE LSPs The solution SHOULD support PCE architecture for a C-TE LSP establishment in the context of a VRF instance. When a C-TE LSP is provided, CEs, PEs and Ps may support PCE [RFC4655] and [RFC5440] features. In this case, CE routers or PE routers may be PCCs and PE routers and/or P routers may be PCEs. Furthermore, the solution SHOULD support a mechanism for dynamic PCE discovery. Specifically, all PCEs are not necessarily discovered automatically and only specific PCEs that know VPN routes should be discovered automatically. 5.9 Diversely Routed C-TE LSPs Support The solution MUST provide for setting up diversely routed C-TE LSPs over VRF instance. These diverse C-TE LSPs MAY be traversing over two different P-TE LSPs that are fully disjoint within a service provider network. When a single CE has multiple uplinks which connect to different PEs, it is desirable that multiple C-TE LSPs over VRF instance are established between a pair of LSRs. When two CEs have multiple uplinks which connect to different PEs, it is desirable that multiple C-TE LSPs over VRF instance are established between two different pairs of LSRs. In these cases, for example, the following points will be beneficial to customers. 1. load balance of CE-to-CE traffic across diverse C-TE LSPs so as to minimize the traffic disruption in case of a single network element or link failure. 2. path protection (e.g. 1:1, 1:N) K.Kumaki, et al. [Page 15] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 5.10 Optimal Path Support for C-TE LSPs The solution MUST support an optimal path for a C-TE LSP over VRF instance. Depending on an application (e.g. voice and video), an optimal path is needed for a C-TE LSP over vrf instance. An optimal path may be a shortest path based on TE metric, in the case of a TE-LSP or IGP metric, in the case of LDP. 5.11 Reoptimization Support for C-TE LSPs The solution MUST support reoptimization of a C-TE LSP over VRF instance. These LSPs MUST be reoptimized using make-before-break. In this case, it is desirable for a CE to be configured with regard to timer-based or event-driven reoptimization. Furthermore, customers SHOULD be able to reoptimize a C-TE LSP manually. To provide delay-sensitive or jitter-sensitive traffic (i.e. voice traffic), a C-TE LSP path computation and route selection is expected to optimal for the specific application. 5.12 DS-TE Support for C-TE LSPs The solution MUST support DS-TE [RFC4124] for a C-TE LSP over VRF instance. In the event that service provider and customer have differing bandwidth constraint models, then only the service provider bandwidth model should be supported. Applications, which have different traffic characteristics, are used in BGP/MPLS IP-VPN environments. Service providers try to achieve fine-grained optimization of transmission resources, efficiency and further enhanced network performance. It may be desirable to perform TE at a per-class level. By mapping the traffic from a given diff-serv class of service on a separate C-TE LSP, it allows this traffic to utilize resources available to the given class on both shortest paths and non-shortest paths, and follow paths that meet TE constraints which are specific to the given class. 6. Detailed Requirements for C-RSVP Paths Model This section describes detailed requirements for C-RSVP paths in BGP/MPLS IP-VPN environments. 6.1 Admission Control between PE-CE for C-RSVP Paths The solution MUST support admission control at the ingress/egress PE. PEs MUST be able to control the amount of RSVP messages per a VRF. K.Kumaki, et al. [Page 16] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 6.2 Aggregation of C-RSVP Paths by P-TE LSPs The solution SHOULD support C-RSVP paths aggregated by P-TE LSPs. P-TE LSPs SHOULD be pre-established by manually or dynamically, MAY be established triggered by C-RSVP message. Also, P-TE LSP SHOULD support DS-TE. 6.3 Non-TE LSPs support for C-RSVP Paths The solution SHOULD support non-TE LSPs (i.e. LDP-based LSP, etc). They are provided between PEs and supports MPLS diffserv [RFC3270]. Local policies can be implemented to map customer's reserved flow to the LSP with the appropriate EXP at PE. 6.4 Transparency of C-RSVP Paths The solution SHOULD NOT change RSVP messages from local CE to remote CE (Path, Resv, Path Error, Resv Error, etc). Customers SHOULD receive RSVP messages transparently between CE sites. 7. Common Detailed Requirements for Two Models This section describes common detailed requirements for C-TE LSPs and C-RSVP paths in BGP/MPLS IP-VPN environments. 7.1 CE-PE Routing The solution SHOULD support the following routing configuration on the CE-PE links with either RSVP or RSVP-TE on the CE-PE link: 1. static routing 2. BGP routing 3. OSPF 4. OSPF-TE (RSVP-TE case only) It should be noted that routing configuration 4 (OSPF-TE) may be subject to a security issue as potential service provider TE capabilities and topology information may be shared with the customer. 7.2 Complexity and Risks The solution SHOULD avoid introducing unnecessary complexity to the current operating network to such a degree that it would affect the stability and diminish the benefits of deploying such a solution over SP networks. K.Kumaki, et al. [Page 17] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 7.3 Backward Compatibility The deployment of C-RSVP paths and C-TE LSPs SHOULD avoid impacting existing RSVP and MPLS TE mechanisms respectively, but allow for a smooth migration or co-existence. 7.4 Scalability Considerations The solution should minimize impact on network scalability from a C-RSVP path and a C-TE LSP over VRF instance. As indentified in earlier sections, PCE provides a method for offloading computation of C-TE LSPs and help with solution scalability. Scalability of C-RSVP paths and C-TE LSPs MUST address the following consideration. 1. RSVP (e.g. number and rate of RSVP messages, retained state etc). 2. RSVP-TE (e.g. number and rate of RSVP control messages, retained state, message size etc). 3. BGP (e.g. number of routes, flaps, overloads events etc). 7.5 Performance Considerations The solution SHOULD be evaluated with regard to the following criteria. 1. Degree of path optimality of the C-TE LSP. 2. C-TE LSP setup time. 3. Failure detection and restoration time. 4. Impact and scalability of the control plane due to added overhead. 5. Impact and scalability of the data/forwarding plane due to added overhead. 7.6 Management Considerations Manageability of C-RSVP paths and C-TE LSPs MUST addresses the following considerations. 1. Need for a MIB module for control plane (including mapping of P-TE LSP and C-TE LSPs) and bandwidth monitoring. 2. Need for diagnostic tools (this include Trace Route and PING) MIB module for C-RSVP paths and C-TE LSPs MUST collect per a vrf instance. If a CE is managed by service providers, MIB information for C-RSVP paths and C-TE LSPs from the CE MUST be collected per a customer. K.Kumaki, et al. [Page 18] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 Diagnostic tools can detect failures of control plane and data plane for general MPLS TE LSPs [RFC4379]. Any diagnostic tool MUST be capable of detecting failures of the control and data plane for C-TE LSPs over a VRF instance. MPLS OAM for C-TE LSPs MUST be supported within the context of VRF except for the above. 8. Security Considerations Any solution should consider the following general security requirements: 1. The solution should not divulge service provider topology information to the customer network. 2. Minimize service provider network vulnerability to Denial of Service (DoS) attacks. 3. Minimize misconfiguration of DSCP marking, preemption, and holding priorities of customer traffic. The following additional security issues for C-TE LSPs relate to both control plane and data plane. In terms of control plane, in the models of C-RSVP paths and C-TE LSPs both, a PE receives IPv4 or IPv6 RSVP control packets from a CE. If the CE is an untrusted router for service providers, the PE MUST be able to limit the rate and number of IPv4 or IPv6 RSVP control packets. In terms of data plane, in the model of C-TE LSPs, a PE receives labeled IPv4 or IPv6 data packets from a CE. If the CE is an untrusted router for service providers, the PE MUST be able to limit the rate labeled IPv4 or IPv6 data packets. If the CE is a trusted router for service providers, the PE MAY be able to limit labeled IPv4 or IPv6 data packets. Specifically, the PE must drop MPLS- labeled packets if the MPLS label was not assigned over the PE-CE link on which the packet was received. The PE must also be able to police traffic to the traffic profile associated with the LSP on which traffic is received on the PE-CE link. Moreover, flooding RSVP/RSVP-TE control packets from malicious customers must be avoided. Therefore, a PE MUST isolate the impact of such customer's RSVP/ RSVP-TE packets from other customers. In the event that C-TE LSPs are diversely routed over VRF instances, the VRF should indicate to the CE how such diversity was provided. K.Kumaki, et al. [Page 19] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 9. IANA Considerations This requirement document makes no requests for IANA action. 10. References 10.1 Normative References [RFC1633] Braden, R., et al., "Integrated Services in the Internet Architecture: an Overview", RFC 1633, June 1994. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated Services", RFC 2210, September 1997. [RFC3270] Le Faucheur, F., "Multi-Protocol Label Switching (MPLS) Support of Differentiated Services", RFC 3270, May 2002. [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC3623] Moy, J., et al., "Graceful OSPF Restart", RFC3623, November 2003. [RFC4090] Pan, P., Swallow, G. and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. [RFC4124] Le Faucheur, F., "Protocol Extensions for Support of Diffserv-aware MPLS Traffic Engineering", RFC 4124, June 2005. [RFC4364] Rosen, E., and Rekhter, Y., "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, February 2006. [RFC4379] Kompella, K. and G. Swallow, "Detecting MPLS Data Plane Failures", RFC 4379, February 2006. [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "Path Computation Element (PCE) Architecture", RFC 4655, August 2006. [RFC4781] Rekhter, Y., and Aggarwal, R., "Graceful Restart Mechanism for BGP with MPLS", RFC 4781, January 2007. K.Kumaki, et al. [Page 20] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 10.2 Informative References [RSVP-L3VPN] Davie, B., et al., "Support for RSVP in Layer 3 VPNs", Work in Progress, May 2009. [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009. [RFC4804] Le Faucheur, F., et al., "Aggregation of RSVP Reservations over MPLS TE/DS-TE Tunnels", RFC4804, February 2007. [RFC5330] Vasseur, J.-P., et al., "A Link-Type sub-TLV to convey the number of Traffic Engineering Label Switched Paths signaled with zero reserved bandwidth across a link", RFC5330, October 2008. 11. Acknowledgments The author would like to express the thanks to Nabil Bitar, David McDysan and Daniel King for their helpful comments and feedback. 12. Author's Addresses Kenji Kumaki (Editor) KDDI Corporation Garden Air Tower Iidabashi, Chiyoda-ku, Tokyo 102-8460, JAPAN Email: ke-kumaki@kddi.com Raymond Zhang BT Infonet 2160 E. Grand Ave. El Segundo, CA 90025 Email: raymond.zhang@bt.infonet.com Yuji Kamite NTT Communications Corporation Tokyo Opera City Tower 3-20-2 Nishi Shinjuku, Shinjuku-ku Tokyo 163-1421, Japan Email: y.kamite@ntt.com K.Kumaki, et al. [Page 21] draft-ietf-l3vpn-e2e-rsvp-te-reqts-034 July 2009 Appendix A. Reference Model In this appendix, a C-RSVP path, a C-TE LSP and a P-TE LSP are explained. All scenarios in this appendix assume the following: - A P-TE LSP is established between PE1 and PE2. This LSP is used by the VRF instance to forward customer packets within BGP/MPLS IP- VPN - The Service Provider has ensured that enough bandwidth is available to meet the service requirements. A.1 End-to-End C-RSVP Path Model A C-RSVP path and a P-TE LSP are shown in figure 3 in the context of a BGP/MPLS IP-VPN. A P-TE LSP may be a non-TE LSP (i.e. LDP) in some cases. In the case of non-TE mechanism, however, it may be difficult to guarantee end-to-end bandwidth as resources are shared. CE0/CE1 requests an e2e C-RSVP path to CE3/CE2 with bandwidth reservation of X. At PE1, this reservation request received in the context of a VRF will get aggregated onto a pre-established P-TE LSP, or trigger the establishment of a new P-TE LSP. It should be noted that C-RSVP sessions across different BGP/MPLS IP-VPNs can be aggregated onto the same P-TE LSP between the same PE pair, achieving further scalability. [RFC4804] defines this scenario in more detail. The RSVP control messages (e.g. an RSVP PATH message and an RSVP RESV message) exchanged among CEs are forwarded by IP packets through BGP/MPLS IP-VPN. After CE0 and/or CE1 receive a reservation message from CE2 and/or CE3, CE0/CE1 establishes a C-RSVP path through the BGP/MPLS IP-VPN. K.Kumaki, et al. [Page 22] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 C-RSVP path <----------------------------------------------> P-TE LSP <---------------------------> ............. ............. . --- --- . --- --- --- --- . --- --- . .|CE0| |CE1|-----|PE1|----|P1 |-----|P2 |----|PE2|-----|CE2| |CE3|. . --- --- . --- --- --- --- . --- --- . ............. ............. ^ ^ | | VRF instance VRF instance <--customer--> <--------BGP/MPLS IP-VPN-------> <--customer-> network network or or another another service provider service provider network network Figure 3 e2e C-RSVP path model A.2 End-to-End C-TE LSP Model A C-TE LSP and a P-TE LSP are shown in figure 4 in the context of a BGP/MPLS IP-VPN. A P-TE LSP may be a non-TE LSP (i.e. LDP) in some cases. As described in previous sub-section, it may be difficult to guarantee end-to-end QoS in some cases. CE0/CE1 requests an e2e TE LSP path to CE3/CE2 with bandwidth reservation of X. At PE1, this reservation request received in the context of a VRF will get aggregated onto a pre-established P-TE LSP, or trigger the establishment of a new P-TE LSP. It should be noted that C-TE LSPs across different BGP/MPLS IP-VPNs can be aggregated onto the same P-TE LSP between the same PE pair, achieving further scalability. The RSVP-TE control messages (e.g. a RSVP PATH message and a RSVP RESV message) exchanged among CEs are forwarded by labeled packet through BGP/MPLS IP-VPN. After CE0 and/or CE1 receive a reservation message from CE2 and/or CE3, CE0/CE1 establishes a C-TE LSP through the BGP/MPLS IP-VPN. A P-TE LSP is established between PE1 and PE2. This LSP is used by the VRF instance to forward customer packets within BGP/MPLS IP- VPN. K.Kumaki, et al. [Page 23] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009 C-TE LSP <-----------------------------------------------------------> or C-TE LSP <----------------------------------------------> P-TE LSP <---------------------------> ............. ............. . --- --- . --- --- --- --- . --- --- . .|CE0| |CE1|-----|PE1|----|P1 |-----|P2 |----|PE2|-----|CE2| |CE3|. . --- --- . --- --- --- --- . --- --- . ............. ............. ^ ^ | | VRF instance VRF instance <--customer--> <--------BGP/MPLS IP-VPN-------> <--customer-> network network or or another another service provider service provider network network Figure 4 e2e C-TE LSP model K.Kumaki, et al. [Page 24] draft-ietf-l3vpn-e2e-rsvp-te-reqts-04 July 2009