Network Working Group Raymond Key Internet Draft Simon Delord Category: Informational Frederic Jounay, France Telecom Expires: October 2010 April 7, 2010 Requirements for MEF E-Tree Support in VPLS draft-key-l2vpn-vpls-etree-reqt-00.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 October 7, 2010. Abstract This document provides functional requirements for Metro Ethernet Forum (MEF) Ethernet Tree (E-Tree) support in Virtual Private LAN Service (VPLS). It is intended that potential solutions will use these requirements as guidelines. Key, et al. Expires October 2010 [Page 1] Internet Draft Requirement E-Tree in VPLS April 2010 Conventions used in this document 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]. Table of Contents 1. Introduction....................................................3 2. Virtual Private LAN Service.....................................3 3. MEF Multipoint Ethernet Services................................3 3.1. Similarity between E-LAN and E-Tree...........................3 3.2. Difference between E-LAN and E-Tree...........................3 3.3. E-Tree Use Cases..............................................4 4. Problem Statement...............................................5 4.1. Motivation....................................................5 4.2. Leaf-to-Leaf Communication Restriction........................5 5. Requirements....................................................6 5.1. Functional Requirements.......................................6 5.2. Applicability.................................................6 5.3. Backward Compatibility........................................6 6. Security Consideration..........................................7 7. IANA Considerations.............................................7 8. Acknowledgements................................................7 9. References......................................................7 9.1. Normative References..........................................7 9.2. Informative References........................................7 Authors' Addresses.................................................8 Intellectual Property and Copyright Statements.....................8 Key, et al. Expires October 2010 [Page 2] Internet Draft Requirement E-Tree in VPLS April 2010 1. Introduction This document provides functional requirements for Metro Ethernet Forum (MEF) Ethernet Tree (E-Tree) support in Virtual Private LAN Service (VPLS). It is intended that potential solutions will use these requirements as guidelines. Considerable number of service providers have adopted VPLS to provide MEF Ethernet LAN (E-LAN) services to customers. Service Providers currently need a simple and effective solution to emulate E-Tree services in addition to E-LAN services on their MPLS networks. 2. Virtual Private LAN Service VPLS is a L2VPN service that provides multipoint-to-multipoint connectivity for Ethernet across an IP or MPLS-enabled IP Packet Switched Network. VPLS emulates the Ethernet VLAN functionality of traditional Ethernet network. VPLS is a current IETF standard, please refer to [RFC4761] [RFC4762]. Data frame is Ethernet frame. Data forwarding is MAC-based forwarding, which includes MAC address learning and aging. 3. MEF Multipoint Ethernet Services MEF has defined two multipoint Ethernet Service types: - E-LAN (Ethernet LAN), multipoint-to-multipoint service - E-Tree (Ethernet Tree), rooted-multipoint service For full specification, please refer to [MEF6.1] [MEF10.2]. 3.1. Similarity between E-LAN and E-Tree Data frame MUST be Ethernet frame. Data forwarding can be MAC-based forwarding or something else, to be specified by service provider as service frame delivery attributes in the particular service definition. A generic E-LAN/E-Tree service is always bidirectional in the sense that ingress frames can originate at any endpoint in the service. 3.2. Difference between E-LAN and E-Tree Within the context of a multipoint Ethernet service, each endpoint is designated as either a Root or a Leaf. A Root can communicate with all other endpoints in the same multipoint Ethernet service, however a Leaf can only communicate with Roots but not Leafs. Key, et al. Expires October 2010 [Page 3] Internet Draft Requirement E-Tree in VPLS April 2010 The only difference between E-LAN and E-Tree is: - E-LAN has Root endpoints only, which implies there is no communication restriction between endpoints - E-Tree has both Root and Leaf endpoints, which implies there is a need to enforce communication restriction between Leaf endpoints 3.3. E-Tree Use Cases Table 1 below presents some major E-Tree use cases. +---------------------------+--------------+------------+ | Use Case | Root | Leaf | +---+---------------------------+--------------+------------+ | 1 | Broadcast Video | Video Source | Subscriber | | | (unidirectional only) | | | +---+---------------------------+--------------+------------+ | 2 | Broadcast/Multicast Video | Video Source | Subscriber | | | plus Control Channel | | | +---+---------------------------+--------------+------------+ | 3 | Internet Access | BNG Router | Subscriber | +---+---------------------------+--------------+------------+ | 4 | IEEE 1588 PTPv2 | PTP Server | PTP Client | | | Clock Synchronisation | | | +---+---------------------------+--------------+------------+ | 5 | Mobile Backhaul | RAN NC | RAN BS | +---+---------------------------+--------------+------------+ | 6 | Hub & Spoke VPN | Hub Site | Spoke Site | +---+---------------------------+--------------+------------+ | 7 | Wholesale Access | Customer's | Customer's | | | | Interconnect | Subscriber | +---+---------------------------+--------------+------------+ | 8 | Device Management | Management | Managed | | | | System | Device | +---+---------------------------+--------------+------------+ Table 1: E-Tree Use Cases Common to all use cases, direct Leaf-to-Leaf communication is not required. For Mobile backhaul, this may not be valid for LTE X2 interfaces in the future. If direct Leaf-to-Leaf communication is not allowed due to security concern, then E-Tree should be used to prohibit communication between Leaf endpoints, otherwise E-LAN is also a feasible option. Also common to the use cases mentioned above, there may be single or multiple Root endpoints in one E-Tree service. The need for multiple Root endpoints is usually driven by redundancy requirement. Whether a particular E-Tree service needs to support single or multiple Root endpoints depends on the target application. Key, et al. Expires October 2010 [Page 4] Internet Draft Requirement E-Tree in VPLS April 2010 A generic E-Tree service supports the following traffic flows: - Unicast bidirectional Root to/from Root - Unicast bidirectional Root to/from Leaf - Broadcast/Multicast unidirectional Root to all Roots and Leafs - Broadcast/Multicast unidirectional Leaf to all Roots A particular E-Tree service may need to support all the above or only a subset depending on the target application. 4. Problem Statement 4.1. Motivation VPLS can be used to emulate MEF E-LAN service over MPLS network provided that the E-LAN service uses MAC-based forwarding as service frame delivery attributes. Considerable number of service providers have adopted VPLS to provide MEF E-LAN services to customers. Service Providers currently need a simple and effective solution to emulate E-Tree services in addition to E-LAN services on their MPLS networks. 4.2. Leaf-to-Leaf Communication Restriction Current standard VPLS treats all ACs equal (i.e. not classified into Root or Leaf) and provides any-to-any connectivity among all ACs. The current standard VPLS does not include any mechanism of communication restriction between specific ACs, therefore is insufficient for emulating generic E-Tree service over MPLS network. Let's look at the scenario illustrated in Figure 1 below. VPLS is used to emulate an E-Tree service over a MPLS network. <------------E-Tree------------> +---------+ +---------+ | PE1 | | PE2 | +----+ | +---+ | | +---+ | +----+ |CE01+----AC1----+--+ | | | | +--+----AC5----+CE05| +----+ (Root AC) | | V | | | | V | | (Root AC) +----+ +----+ | | | | | | | | +----+ |CE02+----AC2----+--+ | | Ethernet | | +--+----AC6----+CE06| +----+ (Root AC) | | S +--+-----PW-----+--+ S | | (Root AC) +----+ +----+ | | | | | | | | +----+ |CE03+----AC3----+--+ | | | | +--+----AC7----+CE07| +----+ (Leaf AC) | | I | | | | I | | (Leaf AC) +----+ +----+ | | | | | | | | +----+ |CE04+----AC4----+--+ | | | | +--+----AC8----+CE08| +----+ (Leaf AC) | +---+ | | +---+ | (Leaf AC) +----+ | | | | +---------+ +---------+ Figure 1: Reference Model for Leaf-to-Leaf Communication Restriction Key, et al. Expires October 2010 [Page 5] Internet Draft Requirement E-Tree in VPLS April 2010 When PE2 receives a frame from PE1 via the PW, - PE2 does not know which AC on PE1 is the ingress AC - PE2 does not know whether the ingress AC is a Leaf AC or not - PE2 does not have sufficient information to enforce the Leaf-to-Leaf communication restriction 5. Requirements 5.1. Functional Requirements A solution MUST prohibit communication between any two Leaf ACs in a VPLS instance. A solution MUST allow multiple Root ACs in a VPLS instance. A solution MUST allow Root AC and Leaf AC of a VPLS instance co-exist on any PE. 5.2. Applicability There are two distinct VPLS standards, performing similar functions in different manners. - [RFC4761], commonly known as BGP-VPLS - [RFC4762], commonly known as LDP-VPLS A solution MUST identify which VPLS standards the solution is applicable to, [RFC4761] or [RFC4762] or both. Service providers may use single or multiple technologies to deliver an end-to-end E-Tree service. - Case 1: Single technology "Just VPLS" - Case 2: Multiple technologies "VPLS + Others" - e.g. VPLS + Ethernet network, VPLS + OTN - Case 3: Single/multiple technologies "No VPLS" - e.g. Ethernet network, Ethernet network + OTN - out of scope for this document A solution MUST identify which of the above cases the solution is applicable to. For Case 2, further details may be required to specify the applicable deployment scenarios. 5.3. Backward Compatibility A solution should minimise the impact on existing VPLS solution, especially for the MEF E-LAN services already in operation. Key, et al. Expires October 2010 [Page 6] Internet Draft Requirement E-Tree in VPLS April 2010 A solution should be backward compatible with the existing VPLS solution. It should allow a case where a common VPLS instance is composed of both PEs supporting the solution and PEs not supporting it, and the Leaf-to-Leaf communication restriction is enforced within the scope of the compliant PEs. 6. Security Considerations This will be added in later version of this document. 7. IANA Considerations This will be added in later version of this document. 8. Acknowledgements This will be added in later version of this document. 9. References 9.1. Normative References [MEF6.1] Metro Ethernet Forum, Ethernet Services Definitions - Phase 2, April 2008 [MEF10.2] Metro Ethernet Forum, Ethernet Services Attributes Phase 2, October 2009 [RFC2119] Bradner, S., Key words for use in RFCs to Indicate Requirement Levels, BCP 14, RFC 2119, March 1997 [RFC4761] Kompella & Rekhter, Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling, January 2007 [RFC4762] Lasserre & Kompella, Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling, January 2007 9.2. Informative References Key, et al. Expires October 2010 [Page 7] Internet Draft Requirement E-Tree in VPLS April 2010 Authors' Addresses Raymond Key Australia Email: raymond.key@ieee.org Simon Delord Australia Email: simon.delord@gmail.com Frederic Jounay France Telecom 2, avenue Pierre-Marzin 22307 Lannion Cedex, France Email: frederic.jounay@orange-ftgroup.com Copyright Notice Copyright (c) 2010 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 (http://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Key, et al. Expires October 2010 [Page 8]