Internet Working Group Y. Jiang L. Yong Internet Draft Huawei M. Paul Deutsche Telekom Intended status: Standards Track F. Jounay France Telecom Orange Expires: September 2011 March 10, 2011 VPLS PE Model for E-Tree Support draft-jiang-l2vpn-vpls-pe-etree-03.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 September 10, 2011. 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. Jiang, et al Expires September 10, 2011 [Page 1] Internet-Draft VPLS PE Model for E-Tree March 2011 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 tagged PWs, the MAC address based Ethernet forwarding engine and the PW works 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.......................................... 2 2. Conventions used in this document..................... 4 3. Terminology........................................... 4 4. PE Model with E-Tree Support.......................... 4 4.1. Existing PE Models................................. 4 4.2. A New PE Model with E-Tree Support................. 7 5. PW for E-Tree Support................................. 8 5.1. Tagged Mode PW Encapsulation....................... 8 5.2. VLAN Mapping....................................... 8 5.3. PW Processing...................................... 9 5.3.1. PW Processing in the VLAN Mapping Mode ...... 9 5.3.2. PW Processing in the Compatible Mode......... 10 5.3.3. PW Processing in the Optimized Mode.......... 11 6. LDP Extensions for E-Tree Support..................... 12 7. BGP Extensions for E-Tree Support..................... 14 8. Applicability......................................... 14 9. Security Considerations............................... 14 10. IANA Considerations .................................. 14 11. References............................................ 15 11.1. Normative References............................ 15 11.2. Informative References.......................... 15 12. Acknowledgments....................................... 16 Appendix A. Other PE Models for E-Tree..................... 17 A.1. PE Model With a VSI and No bridge.................. 17 1. Introduction The E-Tree service is defined in Metro Ethernet Forum (MEF) as a Rooted-Multipoint EVC service, where traffic from a root can reach any root or leaf, and traffic from a leaf can reach any root, but should never reach a leaf. Further, two or more roots can be used to enhance service reliability and flexibility. Although VPMS or P2MP Jiang, et al Expires September 10, 2011 [Page 2] Internet-Draft VPLS PE Model for E-Tree March 2011 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-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 [RFC4664], moreover, E-Tree services may cross both Ethernet and VPLS domains. Therefore, the support of interconnection between Ethernet and VPLS for an E-Tree service is indispensable. 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 is used to carry traffic originated from the roots and another VLAN is used to carry traffic originated from the leaves. The bridge can then filter on each leaf port all the traffic received on the VLANs associated with the leaves. Therefore, it is better to use the same mechanism in VPLS rather than develop a new mechanism which may not interwork with Ethernet. This document introduces how the Ethernet VLAN solution can be used to support generic E-Tree services in the VPLS. The solution proposed is fully compatible with the IEEE bridge architecture and the IETF PWE3 technology, and VPLS scalability and simplicity is also well kept. With this mechanism, it is also convenient to deploy a converged E-Tree service across both Ethernet and MPLS networks. As an example, a typical VPLS PE model is firstly introduced and extended which consists of a Tree VSI connected to an S-VLAN bridge with a dual-VLAN interface. However, this model is also applicable to a PE with C-VLAN or B-VLAN as its service demarcation. Jiang, et al Expires September 10, 2011 [Page 3] Internet-Draft VPLS PE Model for E-Tree March 2011 This document then discusses the PW encapsulation and PW processing such as VLAN mapping options for transporting E-Tree services in a VPLS. Finally, the extensions for the signaling of E-Tree capability and VLAN mapping negotiation are also discussed. 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 T-VSI: Tree VSI, a VSI with E-Tree support 4. PE Model with E-Tree Support "VPLS only" PE architecture as outlined in Fig. 1 of [Etree-req] is a simplification of the VPLS and PWE3 architecture, the more common VPLS PE architectures are discussed in more details in [RFC 4664] and [vpls-interop]. 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. Jiang, et al Expires September 10, 2011 [Page 4] Internet-Draft VPLS PE Model for E-Tree March 2011 The second PE model is more commonly used, and a typical one following it is depicted in Fig. 1 and Fig. 2 as per [vpls-interop], where the 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 The Model of 802.1ad Bridge Module +----------------------------------------+ | 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 VPLS-capable PE Model Jiang, et al Expires September 10, 2011 [Page 5] Internet-Draft VPLS PE Model for E-Tree March 2011 In this PE model, Ethernet service from the CEs will cross multiple stages of bridge modules (i.e., C-VLAN and S-VLAN bridge) and a VSI in a PE to access the egress PWs. Therefore, the association of an AC port and a PW in a single forwarding engine as required in [vpls- etree] or [Etree-2PW] is difficult, sometimes even impossible. This model could be further enhanced by the introduction of a trunk VLAN and a branch VLAN as Ethernet frames enter the PE. To be more precise, they are called root and leaf VLAN respectively in this document. All the egress traffics from the root VLAN are transmitted both on the roots and the leaves, while egress traffics from the leaf VLAN are transmitted on the roots but dropped on the leaves (these VLANs 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. Assume this mechanism is implemented in the bridge module, then 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. +----------------------------------------+ | VPLS-capable PE model | | +---------------+ +------+ | | | | |VSI-1 |------------ | | |==========| |------------ PWs | | Bridge ------------ |------------ | | | Root +------+ | | | Module | S-VLAN o | | | | o | | | (802.1ad | o | | | bridge) | o | | | | Leaf o | | | | S-VLAN +------+ | | | ------------VSI-2 |------------- | | |==========| |------------- PWs | | | ^ | |------------- | +---------------+ | +------+ | | | | +-------------------------|--------------+ LAN emulation Interface Figure 3 VPLS PE Model for E-Tree with 2 VSIs Jiang, et al Expires September 10, 2011 [Page 6] Internet-Draft VPLS PE Model for E-Tree March 2011 4.2. A New PE Model with E-Tree Support To provide for the E-Tree support 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 and depicted in Fig. 4, where the S-VLAN bridge module is connected to the T-VSI with a dual-VLAN virtual interface. That is, both the root S-VLAN and the leaf S-VLAN are connected to the T-VSI. In this way, only one VPLS instance and one set of PWs is needed per E-Tree service. With this model, multiple E-Trees can also be provided by the same T-VSI if needed, and further increase the scalability of VPLS. +----------------------------------------+ | VPLS-capable PE model | | +---------------+ +------+ | | | |==========|TVSI-1|------------ | | ------------ |------------ PWs | | Bridge ------------ |------------ | | | Root & +------+ | | | Module | Leaf VLAN o | | | | o | | | (802.1ad | o | | | bridge) | o | | | | o | | | | S-VLAN-n +------+ | | | ------------VSI-n |------------- | | |==========| |------------- PWs | | | ^ | |------------- | +---------------+ | +------+ | | | | +-------------------------|--------------+ LAN emulation Interface Figure 4 VPLS PE Model for E-Tree with a Single T-VSI In this model, both VLANs should share the same FIB and work in shared VLAN learning. The traffic from the root UNIs are firstly tagged with root C-VLAN by the C-VLAN bridge module, and then tagged with root S-VLAN by the S-VLAN bridge module, thus can only be transported on the root S-VLAN. Similarly, the traffic from the leaves can only be transported on the leaf S-VLAN. In fact, this model can also be applied to a PE with C-VLAN (customer sites attached to the PEs with untagged ports), or B-VLAN (with a PBB bridge module embedded in the PE) as a provider's service demarcation. Therefore, the document will use the VLAN in its more general meaning in the latter sections. Jiang, et al Expires September 10, 2011 [Page 7] Internet-Draft VPLS PE Model for E-Tree March 2011 5. PW for E-Tree Support 5.1. Tagged Mode PW Encapsulation For a VPLS instance to support an E-Tree service, its Ethernet PW should work in the tagged mode (PW type 0x0004) as described in [RFC4448], and a VLAN tag must be carried in each frame in the PW to indicate the E-Tree root/leaf attribute. A pair of T-VSIs in a VPLS is interconnected with a bidirectional PW. The VLAN indicating root/leaf attribute of the packet is carried in the PW, and the peer PE must drop all the packets with a leaf VLAN on each egress port associated with a leaf. 5.2. VLAN Mapping There are three ways of manipulating VLANs for an E-Tree: o Global VLAN based that is, provisioning two global VLANs across both the Ethernet and the VPLS instance domain, no VLAN mapping is needed for this case. o Partial global VLAN based, that is, provisioning two local VLANs in the VLAN space for each Ethernet domain and two global VLANs in the VPLS network domain, the VLAN mapping is done completely in the Ethernet domains (e.g., in the bridge module of the PE or in the Ethernet device attached to the PE), and not needed at all in the VPLS domain. o Local VLAN based, that is, provisioning two local VLANs independently for the VPLS on each PE. The first two methods require no VLAN mapping in the PW, but two unique VLANs must be allocated in the VPLS (they may be provisioned by management or signaled by some control protocols), and the PW processing procedure as described in RFC 4448 applies. The last 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]. It is assumed that for each PE with E- Tree capability there is a VLAN mapping module that can be enabled when VLAN mapping is needed for a PW. Actual VLAN mapping mode can be provisioned or determined by a signaling protocol as described in Section 6 when PW is being established. Jiang, et al Expires September 10, 2011 [Page 8] Internet-Draft VPLS PE Model for E-Tree March 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|------|C-VLAN|---|S-VLAN |---|T-VSI|---------- +----+ | | BRG | | BRG | | |---------- +----+ | | |---| |---| |---------- |Leaf|------| | | | | |---------+ +----+ | +------+ +-------| +-----+ | | | | | +--------------------------------+ | | +--------------------------------+ | | VPLS PE with T-VSI | | | | | +----+ | +------+ +-------+ +-----+ | PW | |Root|------|C-VLAN|---|S-VLAN |---|T-VSI|---------+ +----+ | | BRG | | 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 packet as follows: o Upon transmit 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 receive on the PW, map from remote VLAN to local VLAN, and the packet is further forwarded or dropped in the egress bridge module using the filtering mechanism as described in IEEE 802.1Q. Jiang, et al Expires September 10, 2011 [Page 9] Internet-Draft VPLS PE Model for E-Tree March 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 access root and/or leaf nodes, while the VPLS PE with a traditional VSI can only access root nodes. +--------------------------------+ | VPLS PE with T-VSI | | | +----+ | +------+ +-------+ +-----+ | PW |Root|------|C-VLAN|---|S-VLAN |---|T-VSI|---------- +----+ | | BRG | | BRG | | |---------- +----+ | | |---| |---| |---------- |Leaf|------| | | | | |---------+ +----+ | +------+ +-------| +-----+ | | | | | +--------------------------------+ | | +--------------------------------+ | | VPLS PE with VSI | | | | | +----+ | +------+ +-------+ +-----+ | PW | |Root|------|C-VLAN|---|S-VLAN |---|VSI |---------+ +----+ | | BRG | | 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 packet as follows: o Upon transmit on the PW, map both local root and local leaf VLAN to the remote VLAN. o Upon receive on the PW, map the remote VLAN to the local root VLAN. Jiang, et al Expires September 10, 2011 [Page 10] Internet-Draft VPLS PE Model for E-Tree March 2011 5.3.3.PW Processing in the Optimized Mode When two VPLS PE with T-VSI are inter-connected and one PE (e.g., PE2) is attached with pure leaves, as shown in the scenario of Fig. 6, the peer PE (e.g., PE1) should then work in the optimization mode, that is, the PE1 can drop all the frames received over the local leaf VLAN rather than transport them over the PW and be discarded on the remote PE. Thus bandwidth efficiency of the VPLS can be improved. The signaling for the PE with pure leaves is specified in Section 6. +--------------------------------+ | VPLS PE with T-VSI (PE1) | | | +----+ | +------+ +-------+ +-----+ | PW |Root|------|C-VLAN|---|S-VLAN |---|T-VSI|---------- +----+ | | BRG | | BRG | | |---------- +----+ | | |---| |---| |---------- |Leaf|------| | | | | |---------+ +----+ | +------+ +-------| +-----+ | | | | | +--------------------------------+ | | +--------------------------------+ | | VPLS PE with T-VSI (PE2) | | | | | +----+ | +------+ +-------+ +-----+ | PW | |Leaf|------|C-VLAN|---|S-VLAN |---|T-VSI|---------+ +----+ | | BRG | | BRG | | |---------- +----+ | | |---| |---| |---------- |Leaf|------| | | | | |---------- +----+ | +------+ +-------| +-----+ | | | +--------------------------------+ Figure 7 T-VSI interconnected with 1-side of pure Leaves If a PE is in the Optimized Mode for a PW, then in the data plane, before proceeding as listed in Section 5.3.1 upon transmit, the PE SHOULD first operate as follows: o Drop a frame if it has a local leaf VLAN. Jiang, et al Expires September 10, 2011 [Page 11] Internet-Draft VPLS PE Model for E-Tree March 2011 6. LDP Extensions for E-Tree Support To dynamically provision the E-Tree service and negotiate a single PE to carry out the VLAN mapping function using the signaling procedures as specified in [RFC4447], an E-Tree specific interface parameter sub-TLV is proposed 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 Pure Leaf bit, it is set to 1 to indicate that the PE is attached with all 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 the VPLS supporting an E-Tree service is setting up the PW, the PW endpoints 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 includes an E-Tree Sub-TLV in its PW label mapping message, with its local root VLAN and leaf VLAN carried in the Root VLAN ID and Leaf VLAN ID field respectively. A PE that has the VLAN mapping capability MUST set the V bit to 1, and a PE is attached with pure leaves SHOULD set the P bit to 1. Jiang, et al Expires September 10, 2011 [Page 12] Internet-Draft VPLS PE Model for E-Tree March 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 exit; 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 pure leaf 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. } Jiang, et al Expires September 10, 2011 [Page 13] Internet-Draft VPLS PE Model for E-Tree March 2011 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- Mode to TRUE if the PE is VLAN mapping capable, otherwise a label release message is sent. Data plane processing for this PW is as following: If VLAN-Mapping-Mode is TRUE, then data plane processing is as described in Section 5.3.1. If Optimized-Mode is TRUE, then data plane processing is as described in Section 5.3.3. If Compatible-Mode is TRUE, then data plane processing is as described in Section 5.3.2. PW processing as described in RFC 4448 proceeds as usual. 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 [RFC 4761]. The solution is applicable to both "VPLS Only" network and VPLS with Ethernet aggregation network. 9. Security Considerations To be added in the next version. 10. IANA Considerations IANA is requested to allocate a value for E-Tree in the Pseudowire Interface Parameters Sub-TLV type registry. 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: Jiang, et al Expires September 10, 2011 [Page 14] Internet-Draft VPLS PE Model for E-Tree March 2011 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. [vpls-interop] Sajassi, A., and et al, "VPLS Interoperability with CE Bridges", draft-ietf-l2vpn-vpls-bridge-interop-06, October 2010 [ETree-req] Key, R., et al, "Requirements for MEF E-Tree Support in VPLS", draft-key-l2vpn-vpls-etree-reqt-02, October 2010 [vpls-etree] Delord, S., and et al, "Extension to VPLS for E-Tree", draft-key-l2vpn-vpls-etree-04, October 2010 [802.1aq] IEEE 802.1aq D3.0, Virtual Bridged Local Area Networks - Amendment 9: Shortest Path Bridging, June 2010 Jiang, et al Expires September 10, 2011 [Page 15] Internet-Draft VPLS PE Model for E-Tree March 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-00.txt, October 2010 12. Acknowledgments The authors would like to thank Adrian Farrel and Susan Hares for their valuable comments and advices. Jiang, et al Expires September 10, 2011 [Page 16] Internet-Draft VPLS PE Model for E-Tree March 2011 Appendix A. Other PE Models for E-Tree A.1. 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 PE model with a VSI and no bridge module Jiang, et al Expires September 10, 2011 [Page 17] Internet-Draft VPLS PE Model for E-Tree March 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 Jiang, et al Expires September 10, 2011 [Page 18]