Network Working Group Rafi Ram, Orckit-Corrigent Internet Draft Daniel Cohn, Orckit-Corrigent Category: Standard Track Raymond Key, Huawei P. Agarwal, Broadcom Yuqun (Sam) Cao, Ruijie Networks Expires: August 13, 2012 February 13, 2012 Extension to VPLS for E-Tree Using Multiple PWs draft-ram-l2vpn-etree-multiple-pw-00 Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. 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 in August 13, 2012. Ram, et al. Expires Aug 2012 [Page 1] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 Copyright Notice Copyright (c) 2011 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. Abstract This document proposes a solution for Metro Ethernet Forum (MEF) Ethernet Tree (E-Tree) support in Virtual Private LAN Service using LDP Signaling (LDP-VPLS) [RFC4762] or BGP signaling (BGP-VPLS) [RFC4761]. The proposed solution is characterized by the use of two PWs between a pair of PEs. This solution is applicable for both VPLS and H-VPLS. Table of Contents 1. Introduction ................................................... 3 2. Conventions used in this document............................... 3 3. The Problem .................................................... 3 4. The 2-PW Solution .............................................. 4 5. AC E-Tree Type ................................................. 5 6. Extension to LDP-VPLS for E-Tree................................ 5 6.1. VSI E-Tree Type and Identifier.......................... 5 6.1.1. VSI E-Tree Type Encoding .......................... 6 6.1.2. VSI E-Tree Identifier Encoding..................... 6 6.2. Root/Leaf PWs Signaling................................. 6 6.3. Supporting Remote AC.................................... 7 7. Extension to BGP-VPLS for E-Tree................................ 8 7.1. Auto-discovery ......................................... 8 7.2. PW Setup and Teardown................................... 8 7.3. Root/Leaf PWs Signaling................................. 8 7.4. Optimization ........................................... 9 8. Data Forwarding Requirements.................................... 9 9. Backward Compatibility ........................................ 10 9.1. LDP-VPLS .............................................. 10 9.2. BGP-VPLS .............................................. 10 10. Compliance with Requirements.................................. 10 Ram et al. Expires Aug 2012 [Page 2] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 11. Security Considerations....................................... 10 12. IANA Considerations .......................................... 11 13. Acknowledgements ............................................. 11 14. References ................................................... 11 14.1. Normative References.................................. 11 14.2. Informative References................................ 11 1. Introduction This document proposes a solution for Metro Ethernet Forum (MEF) Tree (E-Tree) support in Virtual Private LAN Service using LDP Signaling (LDP-VPLS) [RFC4762] or BGP Signaling (BGP-VPLS) [RFC4761]. [Draft ETree VPLS Req] is used as requirement specification. The proposed solution is characterized by the use of two PWs between a pair of PEs, which requires extension to the current VPLS standards [RFC4762] and [RFC4761]. This solution is applicable for both VPLS and H-VPLS. The proposed solution is composed of three main components: o Current VPLS standards: LDP-VPLS [RFC4762] and BGP-VPLS [RFC4761] o Extensions to the above specified in this document o PE local split horizon mechanism 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 [RFC2119]. In this document, these words will appear with that interpretation only when in ALL CAPS. Lower case uses of these words are not to be interpreted as carrying RFC-2119 significance. 3. The Problem [Draft ETree VPLS Req] identifies the problem when there are two or more PEs with both Root AC and Leaf AC. Ram et al. Expires Aug 2012 [Page 3] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 <-----------E-Tree----------> +---------+ +---------+ | PE1 | | PE2 | +---+ | +---+ | | +---+ | +---+ |CE1+----AC1----+--+ | | | | +--+----AC3----+CE3| +---+ (Root AC) | | V | | | | V | | (Root AC) +---+ | | S +--+--PW----+--+ S | | +---+ | | I | | | | I | | +---+ |CE2+----AC2----+--+ | | | | +--+----AC4----+CE4| +---+ (Leaf AC) | +---+ | | +---+ | (Leaf AC) +---+ +---------+ +---------+ Figure 1: Problem Scenario for Leaf-to-Leaf Communication Restriction When PE2 receives a frame from PE1 via the Ethernet PW: o PE2 does not know whether the ingress AC is a Leaf AC or not o PE2 does not have sufficient information to enforce the Leaf- to-Leaf communication restriction 4. The 2-PW Solution A simple fix is to carry additional information with each frame on the PW, indicating whether the frame is originated from a Leaf AC or a Root AC on the ingress PE. The proposed solution uses a pair of PWs to interconnect two VPLS PEs: o First PW is used for frames originated from Root ACs o Second PW is used for frames originated from Leaf ACs Ram et al. Expires Aug 2012 [Page 4] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 <--------------E-Tree--------------> +---------+ +---------+ | PE1 | | PE2 | +---+ | +---+ | | +---+ | +---+ |CE1+----AC1----+--+ | | | | +--+----AC3----+CE3| +---+ (Root AC) | | V +--+-VSI Root PW -+--+ V | | (Root AC) +---+ | | S | | | | S | | +---+ | | I +--+-VSI Leaf PW -+--+ I | | +---+ |CE2+----AC2----+--+ | | | | +--+----AC4----+CE4| +---+ (Leaf AC) | +---+ | | +---+ | (Leaf AC) +---+ +---------+ +---------+ Figure 2: Two-PW Solution for Leaf-to-Leaf Communication Restriction The next sections specify the required extension to current VPLS standards. 5. AC E-Tree Type Each AC connected to a specific VPLS instance on a PE MUST have an AC E-Tree Type attribute, either Leaf AC or Root AC. For backward compatibility, the default AC E-Tree Type MUST be Root. This AC E-Tree Type is locally configured on a PE and no signaling is required between PEs. 6. Extension to LDP-VPLS for E-Tree This section specifies extensions to LDP-VPLS [RFC 4762] to support E-Tree requirements. These extensions apply to both FEC types specified in [RFC 4762], namely PWid and generalized PWid. 6.1. VSI E-Tree Type and Identifier Two new PW interface parameters (as defined in section 5.5 of [RFC4447]) are defined for use in E-Tree VPLS: VSI E-Tree type and VSI E-Tree identifier. VSI E-Tree type can be either root or leaf and identifies VSI root PW and VSI leaf PW respectively, as defined in section 4. .. VSI E-tree identifier is a number that is used to identify a pair of root and leaf PW as part of the same logical bridge interface. The pair SHALL be unique among PWs connecting a pair of VPLS PEs for the same VPLS instance. Ram et al. Expires Aug 2012 [Page 5] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 6.1.1. VSI E-Tree Type Encoding The VSI E-Tree type field is encoded as an interface parameters sub- TLV (as defined in section 5.5 of [RFC4447]). The field structure is defined as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type (TBD) | Length (1) | VSI E-Tree Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ VSI E-tree Type can take the following values: 0 E-Tree Root VSI 1 E-Tree Leaf VSI 6.1.2. VSI E-Tree Identifier Encoding The VSI E-Tree identifier field is encoded as an interface parameters sub-TLV (as defined in section 5.5 of [RFC4447]). The field structure is defined as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type (TBD) | Length (1) | VSI E-Tree Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | VSI E-Tree Identifier(cont.) | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ VSI E-tree Identifier is a 32-bit number that is used to identify a pair of root and leaf PW as part of the same logical bridge interface, in the context of a pair of VPLS PEs. The reserved field SHALL be set to zero. 6.2. Root/Leaf PWs Signaling Signaling of root and leaf PWs is required only when two PWs are used for interconnecting between pair of VSIs. As explained in section 6.1: Ram et al. Expires Aug 2012 [Page 6] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 o Root VSI E-Tree type SHALL be used to signal a root PW. o Leaf VSI E-Tree type SHALL be used to signal a leaf PW. PW type signaling rules remain as defined in [RFC4447]. It should be noted that in a full-mesh VPLS (as opposed to H-VPLS), the following VSI pair types do not require two interconnecting PWs: Root-only VSI <-> any VSI: only root PW required Leaf-only VSI <-> leaf-only VSI: no PWs required Where root-only VSI is a VSI where all ACs are of the root type, and leaf-only VSI is one where all ACs are of the leaf type. 6.3. Supporting Remote AC When PW is used to interconnect between VSI and a remote AC (e.g. the PW1, PW2 in Figure 3), an Ethernet Raw or Ethernet tagged PW types SHALL be used as defined in [RFC4762]. <----------------------E-Tree----------> +-------+ +-------+ +----+ | PE1 | | PE2 | +---+ | | | +---+ | | +---+ | |CE1+---AC1---+----+PW1-+-+ | | | | | | +---+ +---+(Root AC)| | | | | | | | +-+---AC4---+CE4| |PE-r| | | V +-+VSI Root PW-+-+ V | |(Root AC)+---+ +---+ | | | | | | | | | | |CE2+---AC2---+----+PW2-+-+ S | | | | S | | +---+(Leaf AC)| | | | | | | | | | +----+ | | I +-+VSI Leaf PW-+-+ I | | +---+ | | | | | | | | +---+ |CE3+--------AC3--------+-+ | | | | +-+---AC5---+CE5| +---+ (Leaf AC) | +---+ | | +---+ |(Leaf AC)+---+ +-------+ +-------+ Figure 3: VPLS with Remote AC Connectivity In addition, the AC type i.e. Root or leaf, SHALL be locally provisioned on the VSI side to specify the remote AC E-Tree Type per PW. Moreover, such PWs that are used for interconnecting between a remote AC and a VSI SHALL considered as separate logical bridge interfaces with respect to MAC address learning/forwarding e.g. Ram et al. Expires Aug 2012 [Page 7] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 traffic forwarding between such PWs is allowed as long as they are not both defined as Leaf. In Figure 3, AC1 is remotely interconnected to the VPLS service via PW1, and AC2 is remotely interconnected to the VPLS service via PW2. AC1 is a Root AC and therefore the local type for PW1 in PE1 SHALL be Root. AC2 is a Leaf AC and therefore the local type for PW2 in PE1 SHALL be Leaf. 7. Extension to BGP-VPLS for E-Tree This section specifies extensions to BGP-VPLS [RFC 4761] to support E-Tree requirements. 7.1. Auto-discovery Requirements in section 3.2.2 of [RFC 4761] apply, with the following modifications. Each PE with SHALL advertise two NLRIs for each VPLS instance, with the same VE-ID and non-overlapping label blocks. The PE SHALL assign one of the NLRIs for root traffic and the other one for leaf traffic by setting the root/leaf flag in the attached Layer2 Info Extended Community, as specified in section 7.2. 7.2. PW Setup and Teardown Requirements in section 3.2.3 of [RFC 4761] apply, with the following modifications. If a PE receives two VPLS NLRI announcements from a remote PE with the same VE-ID and different root/leaf indication, the PE SHALL set up two PWs to the remote PE. PW setup for each of the PWs follows the rules in 3.2.3. 7.3. Root/Leaf PWs Signaling The Layer2 Info Extended Community attribute is used to indicate root/leaf assignment for the associated VPLS NLRI. With reference to Figure 4, bit L in the control flags is defined in this document. Bits C, S have been defined in [RFC4761]. Ram et al. Expires Aug 2012 [Page 8] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 0 1 2 3 4 5 6 7 +-+-+-+-+-+-+-+-+ | MBZ |L|C|S| (MBZ = MUST Be Zero) +-+-+-+-+-+-+-+-+ Figure 4 - Control Flags Bit Vector L can take the following values: 0 E-Tree Root VPLS NLRI 1 E-Tree Leaf VPLS NLRI A PW established following the receipt of a VPLS NLRI with root assignment will be known as root PW. A PW established following the receipt of a VPLS NLRI with leaf assignment will be known as leaf PW. Two PWs established following the receipt of VPLS NLRIs with the same VE-ID SHALL be associated to the same logical bridge interface. 7.4. Optimization As in the LDP case (section 6.2), root and leaf PWs need not be established between every VSI pair. However, BGP optimization to avoid root or leaf PW setup in these cases is not considered in this draft. 8. Data Forwarding Requirements On frame reception, two PWs associated to the same logical bridge interface SHALL be handled as a single bridge interface with respect to MAC address learning/forwarding, e.g. traffic SHALL NOT be forwarded between such PWs and MAC addresses in frames arriving at any of the PWs SHALL be learned on a common logical bridge interface. On transmission, the VPLS processing entity SHALL send root- originated traffic via the root PW, and SHALL send leaf-originated traffic via the leaf PW. An egress PE SHALL NOT deliver a frame originated at a leaf AC to another leaf AC. The following specifies how AC E-Tree type per frame is determined: Ram et al. Expires Aug 2012 [Page 9] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 o A frame received from a root PW indicates that the frame was originated from a root AC. o A frame received from a leaf PW indicates that the frame was originated from a leaf AC. o For the case where both ingress AC and egress AC are on the same PE, local split horizon implementation on the PE will be sufficient, and is not further discussed in this document. 9. Backward Compatibility 9.1. LDP-VPLS Root or leaf VSI E-Tree type and identifier parameters SHALL be used only in cases where both PEs are VPLS capable and both support E- Tree extensions defined in this document. 9.2. BGP-VPLS A PE SHALL announce a leaf VPLS NLRI only to remote PEs that support E-Tree extensions defined in this document. 10. Compliance with Requirements This refers to [Draft ETree VPLS Req] Section 5 Requirements. The solution prohibits communication between any two Leaf ACs in a VPLS instance. The solution allows multiple Root ACs in a VPLS instance. The solution allows Root AC and Leaf AC of a VPLS instance to co- exist on any PE. The solution is applicable to LDP-VPLS [RFC4762] and BGP-VPLS [RFC4762]. The solution is applicable to Case 1: Single technology "VPLS Only". 11. Security Considerations This will be added in later version. Ram et al. Expires Aug 2012 [Page 10] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 12. IANA Considerations Additional assignments will be required for the new interface parameter sub-TLV types introduced in Section 4.2. Details will be added in a later version. 13. Acknowledgements The authors wish to acknowledge the contributions of Luca Martini and Amir Halperin. 14. References 14.1. Normative References [RFC2119] Bradner, S., Key words for use in RFCs to Indicate Requirement Levels, BCP 14, RFC 2119, March 1997. [RFC4447] Martini, L., and al, Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP), April 2006 [RFC4762] Lasserre & Kompella, Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling, January 2007 [RFC4761] Rekhter & Kompella, Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling, January 2007 14.2. Informative References [Draft VPLS ETree Req] Key, et al., Requirements for MEF E-Tree Support in VPLS, draft-key-l2vpn-vpls-etree-reqt-04, September 2011 Authors' Addresses Rafi Ram Orckit-Corrigent 126 Yigal Alon St. Tel Aviv, Israel Email: rafir@orckit.com Daniel Cohn Orckit-Corrigent 126 Yigal Alon St. Tel Aviv, Israel Email: danielc@orckit.com Ram et al. Expires Aug 2012 [Page 11] Internet-Draft Multiple PW Extension to VPLS for E-Tree Feb 2012 Raymond Key Huawei Email: raymond.key@ieee.org Puneet Agarwal Broadcom 3151 Zanker Road San Jose, CA 95134 Email: pagarwal@broadcom.com Yuqun (Sam) Cao Ruijie Networks 618 Jinshan Road, Fuzhou 350002, China Email: yuqun.cao@gmail.com Ram et al. Expires Aug 2012 [Page 12]