Network Working Group Tissa Senevirathne Internet Draft (Force10) Document: draft-tsenevir-bgp-l2vpn-00.txt Category: Informational Loa Anderson Tove Madsen (UTFORS) Pascal Menazes (TeraBeam) June 2001 Use of BGP-MP for Layer 2 VPN Membership discovery Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. 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. For potential updates to the above required-text see: http://www.ietf.org/ietf/1id-guidelines.txt 1. Abstract Membership and configuration discovery is a key component in Layer 2 VPN infrastructure. This document presents use of BGP-MP extensions for Membership and configuration discovery. More specifically, it attempts to extend the mechanism used by [4], commonly called 2547bis [2], to provide both Layer 2 and Layer 3 VPN membership discovery services. Senevirathne Informational - December 2001 1 draft-tsenevir-bgp-l2vpn-00.txt June 2001 2. 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 RFC-2119 [3]. Placement of This Memo in Sub-IP Area RELATED DOCUMENTS: WHERE DOES IT FIT IN THE PICTURE OF THE SUB-IP WORK PPVPN PWE3 WHY IS IT TARGETED AT THIS WG PPVPN WG charter specifies explicitly to consider BGP-VPN services, more specifically based on RFC 2547. In addition WG charter includes Layer 2 Network Based VPN services. The ID discussed here presents methods to provide both Layer 2 and Layer 3 VPN services using RFC 2547. The PWE3 charter specifies "The purpose of the WG is to pursue standardization of the framework and the service-specific techniques for pseudo wires", This ID discuss use of BGP-MP extensions to provide required control plane information for Ethernet emulation. JUSTIFICATION Layer 2 VPN services are gaining popularity in emerging metro services infrastructure. Concepts introduced in RFC 2547 is becoming a popular method in providing Layer 3 VPN services. As Layer 2 VPN becomes available, the same providers may be required to provide both Layer 2 and Layer 3 VPN services. Ability to use same control protocol to provide two classes of VPN not only provide flexibility but also allow investment protection and migration from one class to another or co-offering. 3. Introduction The VPN service introduced in [4] has the potential to become widely used to provide Layer 3 VPN services by service providers. As Layer 2 VPN becomes available, the same providers may be required to provide both Layer 2 and Layer 3 VPN services. Ability to use the same set of control protocols to provide two classes of VPN not only provide flexibility but also allow investment protection and migration from one class to another or co-offering. Senevirathne Informational - December 2001 2 draft-tsenevir-bgp-l2vpn-00.txt June 2001 In this document we introduce required addition to [4] to support Layer 2 VPN services. The architecture and requirements for Layer2 VPN can be found in [5] and [6]. In this document we assume readers are familiar with terminology and concepts used in [4] and [5] [6]. 4. Layer 2 VPN Membership and Configuration discovery In this section we provide the required enhancements to [4] to support Layer 2 VPN discovery. We use the same terminology as in [4] where possible. When providing Layer 2 VPN services, participating PE devices are required to obtain few key parameters; end-points or membership information, VLAN span (usage) and MAC address learning/aging. End-points or Membership information PE devices that participate in a given layer 2 VPN are defined by common membership information. A given PE device MAY support more than one Layer 2 VPN. VLAN span (usage) VLAN span provide a sub-scope within the Layer 2 VPN. VLAN may span only over a subset of end-points. MAC address learning/aging Learning and Aging in Layer 2 VPN is equivalent to routing updates in Layer 3 VPN. However, unlike Layer 3 VPN, Layer 2 VPNs are capable of learning association of a given MAC address to a remote site [5]. In this document we only focus on providing methods to discover Layer 2 VPN memberships and VLAN span. However, if required, MAC addresses learning / aging could easily be accomplished using BGP- MP. NOTE: Currently we see serious scalability issues in the use of BGP-MP for MAC-address learning and aging. 4.1 The Layer 2 VPN Address Family Here we introduce the use of sub address family of Layer 2 VPN-VLAN (L2VPN-VLAN). In [7] the use a SAFI value of 130 for this purpose were defined. 4.2 Encoding NLRI for Layer 2 VPN NLRI for Layer 2 VPN carries VLAN usage information per Layer 2 VPN domain. One may view this as VPN-IPv4 address in [4]. We define the use of a similar encoding format as in [3] for Layer 2 VPN NLRI. Senevirathne Informational - December 2001 3 draft-tsenevir-bgp-l2vpn-00.txt June 2001 Hence, the Layer 2 VPN NLRI starts with an 8 byte Route Distinguisher (RD), followed by an 8 byte VLAN-LABEL. Route Distinguisher The Route Distinguisher for Layer 2 VPNs is coded as follows. The semantics and interpretation of the fields, when applicable, are the same as in [4]. Type field - 2 bytes Value field û 6 bytes Type field The value of the type field for Layer 2 VPNs is, higher bits = 0x00, lower bits 0x[TBD]. Value field The value field contains two sub-fields Administrator The AS number of the SP Assigned Number sub field (4 octets) The Assigned number field contains the Layer 2 VPN domain identifier [5] assigned by SP for this Layer 2 VPN VLAN-LABEL End-point IPV4 address This is the advertising PE device's IP address. This IPV4 address may be used as destination address to setup the tunnel LSP carrying Layer 2 VPN traffic to the advertising PE. VLAN (12 bits) - Represents the VLAN of this Layer 2 VPN Domain that is available at this end-point. Zero (0) in this field denotes ALL VLANs. LABEL (20 bits) - Represents the inner Label associated with this VLAN for this Layer 2 VPN domain for advertising end-point. 4.3 Target Layer 2 VPN attribute. This field has a similar usage like Target VPN attribute in [4]. The Target Layer 2 VPN attribute will be encoded in BGP extended communities. The type of the Target Layer 2 VPN attribute is [TBD]. The Target Layer 2 VPN attribute contain the AS number of the SP and Senevirathne Informational - December 2001 4 draft-tsenevir-bgp-l2vpn-00.txt June 2001 4 byte Layer 2 VPN domain ID. The Target attribute MAY be used either as [4] has suggested or as other local policy. 4.4 Origin Layer 2 VPN attribute This field has a similar usage like Origin VPN attribute in [4]. It is proposed Origin Layer 2 VPN attribute be encoded in BGP extended communities. The type of the Origin Layer 2 VPN attribute is [TBD]. The Origin Layer 2 VPN attribute contain the AS number of the SP and 4 byte Layer 2 VPN domain ID. The Origin attribute MAY be used either as [4] has suggested or as other local policy. 5.0 Further discussion When Layer 2 VPNs PE devices are connected to more than one service provider the AS number in the RD is used to uniquely identify the Layer 2 VPN membership. 6. Security Considerations Security issues relevant to Layer 2 VPN are discussed in [6] and Security issues relevant to use of 2547bis are discussed in [4]. 7. References 1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. 2 Rosen, E., et.al, BGP/MPL VPNs, Work In Progress, February 2001 3 Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 4 Rosen, E., et.al., BGP/MPLS VPNs, RFC 2547, March 1999. 5 Senevirathn, T., et.al, Requirements for Network Based Layer 2 VPN, Work in Progress, May 2001. 6 Senevirathne, T., et.al., A Framework for Virtual Metropolitan Internetworks (VMI), Work In Progress, February 2001. 7 Senevirathne, T., et.al, Distribution of 802.1Q VLAN Information using BGP 4-MP Extensions, Work In Progress, November 2000. 10. Acknowledgments Increasing popularity of Layer 2 VPN services motivated us to publish this work. Senevirathne Informational - December 2001 5 draft-tsenevir-bgp-l2vpn-00.txt June 2001 11. Author's Addresses Tissa Senevirathne Force10 Networks 1440, McCarthy Blvd, Milpitas, CA Phone: 408-865-5103 Email: tsenevir@hotmail.com Loa Andersson Utfors Bredband AB Rasundavagen 12 169 29 Solna Phone: +46 8 5270 50 38 Email: loa.andersson@utfors.se Tove Madsen Utfors Bredband AB Rasundavagen 12 169 29 Solna Phone: +46 8 5270 50 40 Email: tove.madsen@utfors.se Senevirathne Informational - December 2001 6 draft-tsenevir-bgp-l2vpn-00.txt June 2001 Full Copyright Statement "Copyright (C) The Internet Society (2001). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into Senevirathne Informational - December 2001 7