Internet Working Group Y. Jiang L. Yong Internet Draft Huawei Intended status: Standards Track M. Paul Deutsche Telekom F. Jounay France Telecom Orange F. Balus W. Henderickx Alcatel-Lucent Expires: April 2012 October 26, 2011 VPLS PE Model for E-Tree Support draft-jiang-l2vpn-vpls-pe-etree-05.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 April 26, 2012. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. Jiang, et al Expires April 26, 2012 [Page 1] Internet-Draft VPLS PE Model for E-Tree October 2011 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 A generic VPLS solution for E-Tree services is proposed which uses VLANs to indicate root/leaf traffic. A VPLS Provider Edge (PE) model is illustrated as an example for the solution. In the solution, E- Tree VPLS PEs are interconnected by PWs which carry the VLAN indicating the E-Tree attribute, the MAC address based Ethernet forwarding engine and the PW work in the same way as before. A signaling mechanism for E-Tree capability and VLAN mapping negotiation is further described. Table of Contents 1. Introduction .............................................. 3 2. Conventions used in this document ......................... 4 3. Terminology ............................................... 4 4. PE Model with E-Tree Support .............................. 5 4.1. Existing PE Models ..................................... 5 4.2. A New PE Model with E-Tree Support ..................... 8 5. PW for E-Tree Support ..................................... 9 5.1. PW Encapsulation ....................................... 9 5.2. VLAN Mapping ........................................... 9 5.3. PW Processing ......................................... 11 5.3.1. PW Processing in the VLAN Mapping Mode .......... 11 5.3.2. PW Processing in the Compatible Mode ............ 12 5.3.3. PW Processing in the Optimized Mode ............. 13 6. LDP Extensions for E-Tree Support ........................ 14 7. BGP Extensions for E-Tree Support ........................ 16 8. Applicability ............................................ 16 9. Security Considerations .................................. 16 10. IANA Considerations ...................................... 16 11. References ............................................... 17 11.1. Normative References ............................... 17 11.2. Informative References ............................. 17 12. Acknowledgments .......................................... 18 Appendix A. Other PE Models for E-Tree ........................ 19 A.1. A PE Model With a VSI and No bridge ................... 19 A.2. A PE Model With external E-Tree interface ............. 20 Jiang, et al Expires April 26, 2012 [Page 2] Internet-Draft VPLS PE Model for E-Tree October 2011 1. Introduction The E-Tree service is defined in Metro Ethernet Forum (MEF) as a Rooted-Multipoint EVC service. It is a multipoint Ethernet service with special restrictions: the frames from a root may be received by any other root or leaf, and the frames from a leaf may be received by any root, but MUST not be received by a leaf. Further, an E-Tree service may include multiple roots and multiple leaves. Although VPMS or P2MP multicast is a somewhat simplified version of this service, in fact, there is no exact corresponding terminology in IETF. [Etree-req] gives the requirements for providing E-Tree solutions in the VPLS and the need to filter leaf-to-leaf traffic. [Vpls-etree] describes a PW control word based E-Tree solution, where a bit in the PW control word is used to indicate the root/leaf attribute for a packet. The Ethernet forwarder in the VPLS is also extended to filter the leaf-to-leaf traffic based on the tuple. [Etree-2PW] proposes another E-Tree solution where root and leaf traffic are classified and forwarded in the same VSI but with two separate PWs. Both solutions are only applicable to "VPLS only" networks. In fact, VPLS PE usually consists of a bridge module itself (see [RFC4664] and [RFC6246]), moreover, E-Tree services may cross both Ethernet and VPLS domains. Therefore, it is necessary to develop an E-Tree solution both for "VPLS only" scenarios and for interworking between Ethernet and VPLS. IEEE 802.1 has incorporated the generic E-Tree solution in the latest version of 802.1Q [802.1aq], which is just an improvement on the traditional asymmetric VLAN mechanism. In the solution, VLANs are used to indicate root/leaf attribute of a packet: one VLAN ID is used to indicate the frames originated from the roots and another VLAN ID is used to indicate the frames originated from the leaves. At a leaf port, the bridge can then filter out all the frames from other leaf ports based on the VLAN ID. It is better to reuse the same mechanism in VPLS than to develop a new mechanism. The latter will introduce more complexity to interwork with IEEE 802.1Q solution. This document introduces how the Ethernet VLAN solution can be used to support generic E-Tree services in the VPLS. The solution proposed here is fully compatible with the IEEE bridge architecture and the IETF PWE3 technology, and VPLS scalability and simplicity is also Jiang, et al Expires April 26, 2012 [Page 3] Internet-Draft VPLS PE Model for E-Tree October 2011 well kept. With this mechanism, it is also convenient to deploy a converged E-Tree service across both Ethernet and MPLS networks. Firstly, a typical VPLS PE model is introduced as an example, the model is then extended in which a Tree VSI is connected to a VLAN bridge with a dual-VLAN interface. This document then discusses the PW encapsulation and PW processing such as VLAN mapping options for transporting E-Tree services in a VPLS. Finally, it describes the signaling extensions for E-Tree support and PE processing procedures. 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 [RFC2119]. 3. Terminology E-Tree: a Rooted-Multipoint EVC service according to the definition in MEF EVC: Ethernet Virtual Connection, as defined in MEF 4.0 T-VSI: Tree VSI, a VSI with E-Tree support Root AC, an AC attached with a root Leaf AC, an AC attached with a leaf Root VLAN, a VLAN ID used to indicate all the frames that are originated at a root AC Leaf VLAN, a VLAN ID used to indicate all the frames that are originated at a leaf AC Jiang, et al Expires April 26, 2012 [Page 4] Internet-Draft VPLS PE Model for E-Tree October 2011 4. PE Model with E-Tree Support "VPLS only" PE architecture as shown in Fig. 1 of [Etree-req] is a simplification of the VPLS and PWE3 architecture, several common VPLS PE architectures are discussed in more details in [RFC4664] and [RFC6246]. Therefore, VLAN based E-Tree solution are demonstrated with the help of a typical VPLS PE model. Other PE models are further discussed in Appendix A. 4.1. Existing PE Models According to [RFC4664], there are at least three models possible for a VPLS PE, including: o A single bridge module, a single VSI; o A single bridge module, multiple VSIs; o Multiple bridge modules, each attaches to a VSI. The second PE model is commonly used. A typical example is further depicted in Fig. 1 and Fig. 2 [RFC6246], where an S-VLAN bridge module is connected to multiple VSIs each with a single VLAN virtual interface. +-------------------------------+ | 802.1ad Bridge Module Model | | | +---+ | +------+ +-----------+ | |CE |---------|C-VLAN|------| | | +---+ | |bridge|------| | | | +------+ | | | | o | S-VLAN | | | o | | | | o | Bridge | | +---+ | +------+ | | | |CE |---------|C-VLAN|------| | | +---+ | |bridge|------| | | | +------+ +-----------+ | +-------------------------------+ Figure 1 A model of 802.1ad Bridge Module Jiang, et al Expires April 26, 2012 [Page 5] Internet-Draft VPLS PE Model for E-Tree October 2011 +----------------------------------------+ | VPLS-capable PE model | | +---------------+ +------+ | | | | |VSI-1 |------------ | | |==========| |------------ PWs | | Bridge ------------ |------------ | | | S-VLAN-1 +------+ | | | Module | o | | | | o | | | (802.1ad | o | | | bridge) | o | | | | o | | | | S-VLAN-n +------+ | | | ------------VSI-n |------------- | | |==========| |------------- PWs | | | ^ | |------------- | +---------------+ | +------+ | | | | +-------------------------|--------------+ LAN emulation Interface Figure 2 A VPLS-capable PE Model In this PE model, Ethernet frames from Customer Edges (CEs) will cross multiple stages of bridge modules (i.e., C-VLAN and S-VLAN bridge) and a VSI in a PE before being sent on the PW to a remote PE. Therefore, the association between an AC port and a PW on a VSI as required in [Vpls-etree] or [Etree-2PW] is difficult, sometimes even impossible. This model could be further enhanced: When Ethernet frames arrive at a PE, a root VLAN or a leaf VLAN tag is added. Then the frames with the root VLAN tag are transmitted both on the roots and the leaves, while the frames with the leaf VLAN tag are transmitted on the roots but dropped on the leaves (these VLAN tags are removed before the frames are transmitted over the wire). It was demonstrated in [802.1aq] that the E-Tree service in Ethernet networks can be well supported with this mechanism. Assuming this mechanism is implemented in the bridge module, it is quite straightforward to infer a VPLS PE model with two VSIs to support the E-Tree (as shown in Fig. 3). But this model will require two VSIs per PE and two sets of PWs per E-Tree service, which is poorly scalable in a large MPLS/VPLS network; in addition, both these VSIs have to share their learned MAC addresses. Jiang, et al Expires April 26, 2012 [Page 6] Internet-Draft VPLS PE Model for E-Tree October 2011 +----------------------------------------+ | VPLS-capable PE model | | +---------------+ +------+ | | | | |VSI-1 |------------ | | |==========| |------------ PWs | | Bridge ------------ |------------ | | | Root +------+ | | | Module | S-VLAN | | | | | | | (802.1ad | | | | bridge) | | | | | Leaf | | | | S-VLAN +------+ | | | ------------VSI-2 |------------- | | |==========| |------------- PWs | | | ^ | |------------- | +---------------+ | +------+ | | | | +-------------------------|--------------+ LAN emulation Interface Figure 3 A VPLS PE Model for E-Tree with 2 VSIs Jiang, et al Expires April 26, 2012 [Page 7] Internet-Draft VPLS PE Model for E-Tree October 2011 4.2. A New PE Model with E-Tree Support In order to support the E-Tree in a more scalable way, a new VPLS PE model with a single Tree VSI (T-VSI, a VSI with E-Tree support) is proposed. As depicted in Fig. 4, the bridge module is connected to the T-VSI with a dual-VLAN virtual interface, i.e., both the root VLAN and the leaf VLAN are connected to the same T-VSI, and they share the same FIB and work in shared VLAN learning. In this way, only one VPLS instance and one set of PWs is needed per E-Tree service, and the scalability of VPLS is improved. +----------------------------------------+ | VPLS-capable PE model | | +---------------+ +------+ | | | |==========|TVSI-1|------------ +---+AC | | ------------ |------------ PWs |CE |-------| Bridge ------------ |------------ +---+ | | | Root & +------+ | | | Module | Leaf VLAN o | | | | o | | | | o | | | | o | | | | o | +---+AC | | | VLAN-n +------+ | |CE |-------| ------------VSI-n |------------- +---+ | | |==========| |------------- PWs | | | ^ | |------------- | +---------------+ | +------+ | | | | +-------------------------|--------------+ LAN emulation Interface Figure 4 A VPLS PE Model for E-Tree with a Single T-VSI For an untagged port (customer sites attached to the PEs with untagged ports), the Ethernet frames received from the root ACs can be tagged with a root C-VLAN, and optionally be added with another root S-VLAN. Alternatively, the frames from the root ACs can be tagged with the root S-VLAN tag directly in the VPLS network domain. For a C-VLAN tagged port, the Ethernet frames received from the root ACs can be added with a root S-VLAN. Alternatively, the C-VLAN can be translated to the root S-VLAN in the VPLS network domain. For an S-VLAN tagged port, the S-VLAN tag in the Ethernet frames received from the root ACs can be translated to the root S-VLAN in the VPLS network domain. Alternatively, the PBB VPLS PE model (where Jiang, et al Expires April 26, 2012 [Page 8] Internet-Draft VPLS PE Model for E-Tree October 2011 an IEEE 802.1ah bridge module is embedded in the PE) as described in [PBB-VPLS] can be used, and a root B-VLAN or leaf B-VLAN can be added in this case. In a similar way, the traffic from the leaf ACs is tagged and transported on the leaf C-VLAN, S-VLAN or B-VLAN. In all cases, the outermost VLAN in the resulted Ethernet header is used to indicate the E-Tree attribute of an Ethernet frame; this document will use VLAN to refer to this outermost VLAN for simplicity in the latter sections. 5. PW for E-Tree Support 5.1. PW Encapsulation To support an E-Tree service, T-VSIs in a VPLS must be interconnected with a bidirectional Ethernet PW. The Ethernet PW may work in the tagged mode (PW type 0x0004) as described in [RFC4448], and a VLAN tag must be added and carried in each frame in the PW to indicate the frame originated from either root or leaf. In the tagged PW mode, two service delimiting VLANs must be allocated in the VPLS domain for an E-Tree. PW processing for the tagged PW will be described in Section 5.3 of this document. Raw PW (PW type 0x0005 in [RFC4448]) may also be used to carry E-Tree service, as the VLAN tag indicating the frame originated from either root or leaf can be translated by the bridge module or added by an outside Ethernet edge device. In the raw PW mode, two non-service- delimiting VLANs must be allocated in the Ethernet domain for the E- Tree (its operation is specified in [802.1aq]) and the PW will treat all the VLANs as non-service-delimiting and pass them transparently. Raw PW processing is as described in [RFC4448] and will not be discussed further. 5.2. VLAN Mapping There are two ways of manipulating VLANs for an E-Tree in VPLS: o Global VLAN based, that is, provisioning two global VLANs (Root VLAN, Leaf VLAN) across the VPLS network, thus no VLAN mapping is needed at all, or the VLAN mapping is done completely in the Ethernet domains. Jiang, et al Expires April 26, 2012 [Page 9] Internet-Draft VPLS PE Model for E-Tree October 2011 o Local VLAN based, that is, provisioning two local VLANs for each PE (which participates in the E-Tree) in the VPLS network independently. The first method requires no VLAN mapping in the PW, but two unique service delimiting VLANs must be allocated across the VPLS domain. The second method is more scalable in the use of VLANs, but needs a VLAN mapping mechanism in the PW similar to what is already described in Section 4.3 of [RFC4448]. For both methods, VLAN mapping parameters can be provisioned or determined by a signaling protocol as described in Section 6 when PW is being established. Jiang, et al Expires April 26, 2012 [Page 10] Internet-Draft VPLS PE Model for E-Tree October 2011 5.3. PW Processing 5.3.1.PW Processing in the VLAN Mapping Mode In the VLAN Mapping mode, two VPLS PEs with E-Tree capability are inter-connected with a PW (For example, the scenario of Fig. 5 depicts the interconnection of two PEs miscellaneously attached with roots and leaves). +------------------------+ | VPLS PE with T-VSI | | | +----+ | +------+ +-----+ | PW |Root|------| VLAN |-------|T-VSI|---------- +----+ | | BRG | | |---------- +----+ | | |-------| |---------- |Leaf|------| | | |---------+ +----+ | +------+ +-----+ | | | | | +------------------------+ | | +------------------------+ | | VPLS PE with T-VSI | | | | | +----+ | +------+ +-----+ | PW | |Root|------| VLAN |-------|T-VSI|---------+ +----+ | | BRG | | |---------- +----+ | | |-------| |---------- |Leaf|------| | | |---------- +----+ | +------+ +-----+ | | | +------------------------+ Figure 5 T-VSI Interconnected in the Normal Mode If a PE is in the VLAN mapping mode for a PW, then in the data plane the PE MUST map the VLAN in each frame as follows: o Upon transmitting frames on the PW, map from local VLAN to remote VLAN (i.e., the local leaf VLAN in a frame is translated to the remote leaf VLAN; the local root VLAN in a frame is translated to the remote root VLAN). o Upon receiving frames on the PW, map from remote VLAN to local VLAN, and the frames are further forwarded or dropped in the egress bridge module using the filtering mechanism as described in [802.1aq]. Jiang, et al Expires April 26, 2012 [Page 11] Internet-Draft VPLS PE Model for E-Tree October 2011 5.3.2.PW Processing in the Compatible Mode The new VPLS PE model can work in a traditional VPLS network seamlessly in the compatibility mode. As shown in Fig. 6, the VPLS PE with T-VSI can be attached with root and/or leaf nodes, while the VPLS PE with a traditional VSI can only be attached with root nodes. +------------------------+ | VPLS PE with T-VSI | | | +----+ | +------+ +-----+ | PW |Root|------| VLAN |-------|T-VSI|---------- +----+ | | BRG | | |---------- +----+ | | |-------| |---------- |Leaf|------| | | |---------+ +----+ | +------+ +-----+ | | | | | +------------------------+ | | +------------------------+ | | VPLS PE with VSI | | | | | +----+ | +------+ +-----+ | PW | |Root|------| VLAN |-------|VSI |---------+ +----+ | | BRG | | |---------- +----+ | | | | |---------- |Root|------| | | |---------- +----+ | +------+ +-----+ | | | +------------------------+ Figure 6 T-VSI interconnected with Traditional VSI If a PE is in the Compatible mode for a PW, then in the data plane the PE MUST map the VLAN in each frame as follows: o Upon transmitting frames on the PW, map both local root and local leaf VLAN to the remote VLAN. o Upon receiving frames on the PW, map the remote VLAN to the local root VLAN. Jiang, et al Expires April 26, 2012 [Page 12] Internet-Draft VPLS PE Model for E-Tree October 2011 5.3.3.PW Processing in the Optimized Mode When two PEs are connected with their T-VSIs and one PE (e.g., PE2) is attached with only leaves, as shown in the scenario of Fig. 6, the peer PE (e.g., PE1) should then work in the optimization mode. In this case, PE1 should not send the frames originated from the local leaf VLAN to PE2, i.e., these frames are dropped rather than transported over the PW. The bandwidth efficiency of the VPLS can thus be improved. The signaling for the PE attached with only leaves is specified in Section 6. +------------------------+ |VPLS PE with T-VSI (PE1)| | | +----+ | +------+ +-----+ | PW |Root|------| VLAN |-------|T-VSI|---------- +----+ | | BRG | | |---------- +----+ | | |-------| |---------- |Leaf|------| | | |---------+ +----+ | +------+ +-----+ | | | | | +------------------------+ | | +------------------------+ | |VPLS PE with T-VSI (PE2)| | | | | +----+ | +------+ +-----+ | PW | |Leaf|------| VLAN |-------|T-VSI|---------+ +----+ | | BRG | | |---------- +----+ | | |-------| |---------- |Leaf|------| | | |---------- +----+ | +------+ +-----+ | | | +------------------------+ Figure 7 T-VSI interconnected with one side attached with only leaves If a PE is in the Optimized Mode for a PW, operations in the data plane as described in Section 5.3.1 apply here, but upon transmit, the PE SHOULD first operate as follows: o Drop a frame if its VLAN ID matches the local leaf VLAN ID. Jiang, et al Expires April 26, 2012 [Page 13] Internet-Draft VPLS PE Model for E-Tree October 2011 6. LDP Extensions for E-Tree Support In addition to the signaling procedures as specified in [RFC4447], this document proposes a new interface parameter sub-TLV to provision an E-Tree service and negotiate the VLAN mapping function, 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | E-Tree | Length=8 | Reserved |P|V| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Root VLAN ID | Leaf VLAN ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8 E-Tree Sub-TLV Where: o E-Tree is the sub-TLV identifier to be assigned by IANA. o Length is the length of the sub TLV in octets. o Reserved bits MUST be set to zero on transmit and be ignored on receive. o P is a Leaf-only bit, it is set to 1 to indicate that the PE is attached with only leaves, and set to 0 otherwise. o V is a bit indicating the sender's VLAN mapping capability. A PE capable of VLAN mapping MUST set this bit, and clear it otherwise. o Root VLAN ID is the value of the local root VLAN. o Leaf VLAN ID is the value of the local leaf VLAN. When setting up a PW for the E-Tree based VPLS, two PEs negotiate the E-Tree support using the above E-Tree sub-TLV. Note PW type of 0x0004 should be used during the PW negotiation. A PE that wishes to support E-Tree service MUST include an E-Tree Sub-TLV in its PW label mapping message and include its local root VLAN ID and leaf VLAN ID in the TLV. A PE that has the VLAN mapping capability MUST set the V bit to 1, and a PE is attached with only leaves SHOULD set the P bit to 1. Jiang, et al Expires April 26, 2012 [Page 14] Internet-Draft VPLS PE Model for E-Tree October 2011 In default, for each PW, VLAN-Mapping-Mode, Compatible-Mode, and Optimized-Mode are all set to FALSE. A PE that receives a PW label mapping message with an E-Tree Sub-TLV from its peer PE must process it as follows: 1) if the root and leaf VLAN ID in the message match the local root and leaf VLAN ID, then continue to 3); 2) else { if the bit V is cleared, then { if the PE is capable of VLAN mapping, then it MUST set VLAN-Mapping-Mode to TRUE; else { A label release message with the error code "E-Tree VLAN mapping not supported" is sent to the peer PE and exit the process; } } if the bit V is set, and the PE is capable of VLAN mapping, then the PE with the minimum IP address MUST set VLAN-Mapping- Mode to TRUE; } 3) If the P bit is set, then: { If the PE is a leaf-only node itself, then a label release message with the error code "Leaf to Leaf PW error" is sent to the peer PE and exit the process; Else the PE SHOULD set the Optimized-Mode to TRUE. } If a PE has sent an E-Tree Sub-TLV but does not receive any E-Tree Sub-TLV in its peer's PW label mapping message, then set Compatible- Jiang, et al Expires April 26, 2012 [Page 15] Internet-Draft VPLS PE Model for E-Tree October 2011 Mode to TRUE if the PE is VLAN mapping capable, otherwise a label release message is sent and an error is logged. Data plane processing for this PW is as following: If Optimized-Mode is TRUE, then data plane processing is as described in Section 5.3.3. Else if Compatible-Mode is TRUE, then data plane processing is as described in Section 5.3.2. Else if VLAN-Mapping-Mode is TRUE, then data plane processing is as described in Section 5.3.1. PW processing as described in [RFC4448] proceeds as usual for all cases. 7. BGP Extensions for E-Tree Support BGP may also be used to distribute the E-Tree and VLAN mapping information. It is to be specified in the next version. 8. Applicability The solution is applicable to LDP VPLS [RFC4762] and may also be applicable to BGP VPLS [RFC4761]. The solution is applicable to both "VPLS Only" networks and VPLS with Ethernet aggregation networks. The solution is also applicable to PBB VPLS networks. 9. Security Considerations Besides security considerations as described in [RFC4448] and [RFC4762], this solution prevents leaf to leaf communication in the data plane of VPLS when its PEs are interconnected with PWs. In this regard, security can be enhanced for customers with this solution. 10. IANA Considerations IANA is requested to allocate a value for E-Tree in the registry of Pseudowire Interface Parameters Sub-TLV type. Jiang, et al Expires April 26, 2012 [Page 16] Internet-Draft VPLS PE Model for E-Tree October 2011 Parameter ID Length Description ======================================= TBD 8 E-Tree IANA is requested to allocate a new LDP status code from the registry of name "STATUS CODE NAME SPACE". The following value is suggested: Range/Value E Description ------------- ----- ---------------------- TBD 0 E-Tree VLAN mapping not supported 11. References 11.1. 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 et al, "Pseudowire Setup and Maintenance Using Label Distribution Protocol (LDP)", RFC 4447, April 2006. [RFC4448] Martini, L., and et al, "Encapsulation Methods for Transport of Ethernet over MPLS Networks", RFC 4448, April 2006. [RFC4762] Lasserre, M. and Kompella, V., "Virtual Private LAN Services using LDP", RFC 4762, January 2007. 11.2. Informative References [RFC3985] Bryant, S., and Pate, P., "Pseudo Wire Emulation Edge-to- Edge (PWE3) Architecture", RFC 3985, March 2005. [RFC4664] Andersson, L., and Rosen, E., "Framework for Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664, September 2006. [RFC6246] Sajassi, A., and et al, "Virtual Private LAN Service (VPLS) Interoperability with Customer Edge (CE) Bridges", RFC 6246, June 2011 [ETree-req] Key, R., et al, "Requirements for MEF E-Tree Support in VPLS", draft-key-l2vpn-vpls-etree-reqt-04, September 2011 Jiang, et al Expires April 26, 2012 [Page 17] Internet-Draft VPLS PE Model for E-Tree October 2011 [Vpls-etree] Key, R., and et al, "Extension to VPLS for E-Tree", draft-key-l2vpn-vpls-etree-06, October 2011 [802.1aq] IEEE 802.1aq D4.3, Virtual Bridged Local Area Networks - Amendment 9: Shortest Path Bridging, September 2011 [Etree-2PW] Ram, R., and et al., Extension to LDP-VPLS for E-Tree Using Two PW, draft-ram-l2vpn-ldp-vpls-etree-2pw-02, May 2011 [PBB-VPLS] Balus, F., and et al., Extensions to VPLS PE model for Provider Backbone Bridging, draft-ietf-l2vpn-pbb-vpls-pe- model-04, October 2011 12. Acknowledgments The authors would like to thank Adrian Farrel, Susan Hares and Shane Amante for their valuable advices, thank Ben Mack-crane and Edwin Mallette for their valuable comments and discussions. Jiang, et al Expires April 26, 2012 [Page 18] Internet-Draft VPLS PE Model for E-Tree October 2011 Appendix A. Other PE Models for E-Tree A.1. A PE Model With a VSI and No bridge If there is no bridge module in a PE, the PE may consist of Native Service Processors (NSPs) as shown in Figure A.1 (adapted from Fig. 5 of [RFC3985]) where any transformation operation for VLANs (e.g., VLAN insertion/removal or VLAN mapping) may be applied. Thus a root VLAN or leaf VLAN can be added by the NSP depending on the UNI type (root/leaf) associated with the AC over which the packet arrives. Further, when a packet with a leaf VLAN exits a forwarder and arrives at the NSP, the NSP must drop the packet if the egress AC is associated with a leaf UNI. Tagged PW and VLAN mapping work in the same way as in the typical PE model. +----------------------------------------+ | PE Device | Multiple+----------------------------------------+ AC | | | Single | PW Instance <------>o NSP # + PW Instance X<----------> | | | | |------| VSI |----------------------| | | | Single | PW Instance <------>o NSP #Forwarder + PW Instance X<----------> | | | | |------| |----------------------| | | | Single | PW Instance <------>o NSP # + PW Instance X<----------> | | | | +----------------------------------------+ Figure A.1 A PE model with a VSI and no bridge module Jiang, et al Expires April 26, 2012 [Page 19] Internet-Draft VPLS PE Model for E-Tree October 2011 A.2. A PE Model With external E-Tree interface +----------------------------------------+ | PE Device | Root +----------------------------------------+ VLAN | | Single | PW Instance <------>o + PW Instance X<----------> | | | | VSI |----------------------| | | Single | PW Instance | Forwarder + PW Instance X<----------> | | | Leaf | |----------------------| VLAN | | Single | PW Instance <------>o + PW Instance X<----------> | | | +----------------------------------------+ Figure A.2 A PE model with external E-Tree interface A more simplified PE model is depicted in A.2, where Root/Leaf VLANs are directly connected to the same VSI forwarder (any transformation of E-Tree VLANs, e.g., VLAN insertion/removal or VLAN mapping, is performed by outer equipments). Raw PW can be used to transport the E-Tree traffic transparently in the VPLS. This PE model may be deployed as N-PE in H-VPLS, and other scenarios such as providing E- Tree Network-to-Network interfaces. Jiang, et al Expires April 26, 2012 [Page 20] Internet-Draft VPLS PE Model for E-Tree October 2011 Authors' Addresses Yuanlong Jiang Huawei Technologies Co., Ltd. Bantian, Longgang district Shenzhen 518129, China Email: jiangyuanlong@huawei.com Lucy Yong Huawei USA 1700 Alma Dr. Suite 500 Plano, TX 75075, USA Email: lucyyong@huawei.com Manuel Paul Deutsche Telekom Goslarer Ufer 35 10589 Berlin, Germany Email: manuel.paul@telekom.de Frederic Jounay France Telecom Orange 2, avenue Pierre-Marzin 22307 Lannion Cedex, France Email: frederic.jounay@orange-ftgroup.com Florin Balus Alcatel-Lucent 701 E. Middlefield Road Mountain View, CA, USA 94043 Email: florin.balus@alcatel-lucent.com Wim Henderickx Alcatel-Lucent Copernicuslaan 50 2018 Antwerp, Belgium Email: wim.henderickx@alcatel-lucent.com Jiang, et al Expires April 26, 2012 [Page 21]