Internet Working Group Y. Jiang L. Yong Internet Draft Huawei M. Paul Deutsche Telekom Intended status: Standards Track F. Jounay France Telecom Orange Expires: April 2011 October 25, 2010 VPLS PE Model for E-Tree Support draft-jiang-l2vpn-vpls-pe-etree-02.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 25, 2011. 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. Jiang, et al Expires April 25, 2011 [Page 1] Internet-Draft VPLS PE Model for E-Tree October 2010 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 full mesh 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 notification 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. VLAN Mapping.............................................8 5.2. Tagged Mode PW Encapsulation.............................9 5.3. PW Processing...........................................10 5.3.1. PW Processing in the Normal Mode..................10 5.3.2. PW Processing in the Compatibility Mode...........11 5.3.3. PW Processing in the Optimization Mode............12 6. LDP Extensions for E-Tree Support..........................13 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 E-Tree service is defined in Metro Ethernet Forum (MEF) as rooted multi-point 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. Although VPMS or P2MP multicast is a somewhat simplified version of this service, in fact there is no exact corresponding terminology in IETF. Jiang, et al Expires April 25, 2011 [Page 2] Internet-Draft VPLS PE Model for E-Tree October 2010 [Etree-req] gives the requirements to provide E-Tree solutions in the VPLS and the need to filter leaf to leaf traffic in the VPLS. [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. Thus 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. This solution 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 possible 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 applicable to a PE with C-VLAN or B-VLAN as its service demarcation's encapsulation. This document then discusses the PW encapsulation and PW processing such as VLAN mapping options for transporting E-Tree services in a VPLS. Jiang, et al Expires April 25, 2011 [Page 3] Internet-Draft VPLS PE Model for E-Tree October 2010 Finally, the extensions needed to support the signaling of E-Tree capability and VLAN mapping 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 Most of the terminology used here is from [IEEE802.1Q], [IEEE802.1ad], [RFC4664] and [RFC4762]. Terminology specific to this document is introduced as needed in later sections. 4. PE Model with E-Tree Support "VPLS only" PE architecture as outlined in Fig. 1 of [Etree-req] is a simplification of the 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. The second PE model as depicted in Fig. 1 and Fig. 2 is a typical one for VPLS [vpls-interop], where the S-VLAN bridge module is connected to multiple VSIs each with a single VLAN interface. Jiang, et al Expires April 25, 2011 [Page 4] Internet-Draft VPLS PE Model for E-Tree October 2010 +-------------------------------+ | 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 In the PE model above, Ethernet service from the CEs will cross multiple stages of bridge modules (i.e., C-VLAN and S-VLAN bridge) 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. Jiang, et al Expires April 25, 2011 [Page 5] Internet-Draft VPLS PE Model for E-Tree October 2010 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 traffics from the root VLAN are received both on the roots and the leaves, while traffics from the branch VLAN are received on the roots and dropped on the leaves. It was demonstrated in [802.1aq] that E-Tree on Ethernet could 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 (as shown in Fig. 3) to support the E-Tree. But this model will require two VSIs per PE and two sets of full meshed 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 with E-Tree Support Jiang, et al Expires April 25, 2011 [Page 6] Internet-Draft VPLS PE Model for E-Tree October 2010 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 is proposed and depicted in Fig. 4, where the S-VLAN bridge module is connected to the Tree VSI (T-VSI, a VSI with E-Tree support) with a dual-VLAN virtual interface. That is, both the root S-VLAN and the leaf S-VLAN are connected to the Tree VSI (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 E-Tree VPLS-capable PE 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 tag encapsulation. Therefore, the document will use the VLAN tag as a generalized form in the latter sections. Jiang, et al Expires April 25, 2011 [Page 7] Internet-Draft VPLS PE Model for E-Tree October 2010 5. PW for E-Tree Support 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 the packet with a leaf VLAN on the egress AC of leaf UNI. There are three ways of manipulating VLANs for an E-Tree: o Provisioning two global VLANs across both the Ethernet and the VPLS instance domain; o 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). o Provisioning two local VLANs independently for each Ethernet domain and two local VLANs on each PE for better scalability. That is, the assignment of VLANs in the PE may be local to improve the scalability. The first method is called global VLAN based and no VLAN mapping is needed, but two unique VLANs must be allocated in the VPLS for them. The second method is called partial global VLAN based, which needs a VLAN mapping in the bridge module or in the Ethernet device attached to the PE. The last method is called local VLAN based and more scalable, but needs a VLAN mechanism in the PW. VLAN mapping is elaborated in the following section. 5.1. VLAN Mapping In order to carry both VLANs (root and leaf VLAN) in a single PW and map those into the remote peer's VLANs, cares must be taken on both the PEs associated with the PW. Two options of VLAN mapping are possible: o Local mapping, that is, the remote PE is responsible for mapping VLANs into its local VLANs. For the local VLAN based method, VLAN mapping is done when a frame exits the PW; for the partial global VLAN based method, VLAN mapping is done when a frame exits the bridge module. Jiang, et al Expires April 25, 2011 [Page 8] Internet-Draft VPLS PE Model for E-Tree October 2010 o Remote mapping, that is, the local PE is responsible for mapping VLANs into the remote PE's VLANs. For the local VLAN based method, VLAN mapping is done when a frame enters the PW; for the partial global VLAN based method, VLAN mapping is done when a frame enters the bridge module. Normally, each PE does its own local mapping. But when a PE is not capable of VLAN mapping, remote mapping can be done on its peer. If no PE is capable of VLAN mapping, global VLAN based method can be used instead. 5.2. Tagged Mode PW Encapsulation For a VPLS instance to support an E-Tree as described above, the Ethernet PW should work in the tagged mode (PW type 0x0004) as described in [RFC4448], and a C-VLAN, S-VLAN, or B-VLAN tag must be carried in each frame in the PW to indicate the E-Tree root/leaf attribute. For global VLAN based method, it is the global VLAN tag to be carried and no VLAN mapping needed in the VPLS. For the local VLAN or partial global VLAN based method, either the local or the remote VLAN tag could be carried depending on the mapping option. In the local mapping mode, the remote VLANs are carried with no change, while in the remote mapping mode, the local VLANs are carried instead. The mapping between the local VLAN and the remote VLAN (local root VLAN <-> remote root VLAN; local leaf VLAN <-> remote leaf VLAN) should be provisioned by management or signaled by a control protocol such as LDP. The signaling extensions for E-Tree support are provided in Section 6 and 7. Jiang, et al Expires April 25, 2011 [Page 9] Internet-Draft VPLS PE Model for E-Tree October 2010 5.3. PW Processing 5.3.1.PW Processing in the Normal Mode In the normal mode, two VPLS PEs with a T-VSI in each of them are inter-connected and both sides are miscellaneously attached with roots and leaves, as shown in the scenario of Fig. 5. At the PE where a frame exits the PW, if a frame with the remote leaf VLAN is received, then it is mapped to the local leaf VLAN, otherwise, if a frame with the remote root VLAN is received, then it is mapped to the local root VLAN. Packets over both VLANs are processed in the same I- VSI and are further forwarded or dropped in the exit bridge module using the mechanism as described in 802.1Q. +--------------------------------+ | 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 Jiang, et al Expires April 25, 2011 [Page 10] Internet-Draft VPLS PE Model for E-Tree October 2010 5.3.2.PW Processing in the Compatibility Mode The new VPLS PE model can work in a traditional VPLS network seamlessly in the compatibility mode. As shown in Fig. 5, the VPLS PE with T-VSI can access both root and leaf node, while the VPLS PE with a traditional VSI can only access the root node. +--------------------------------+ | 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 In this case, the PE with a T-VSI in it must work in the compatibility mode, that is, the egress PW of the T-VSI must translate frames received over both local root and leaf VLAN into a PW with a single VLAN (i.e., local root VLAN if the peer is capable of rewriting the VLAN, or the remote peer's VLAN otherwise), while the ingress PW only translates the frames received over the PW into the local root VLAN. Jiang, et al Expires April 25, 2011 [Page 11] Internet-Draft VPLS PE Model for E-Tree October 2010 5.3.3.PW Processing in the Optimization Mode When two VPLS PE with T-VSI are inter-connected and one side is attached with pure leaves, as shown in the scenario of Fig. 6, the egress PW of the miscellaneous attached PE then should work in the optimization mode, that is, the PE 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. +--------------------------------+ | VPLS PE with T-VSI | | | +----+ | +------+ +-------+ +-----+ | PW |Root|------|C-VLAN|---|S-VLAN |---|T-VSI|---------- +----+ | | BRG | | BRG | | |---------- +----+ | | |---| |---| |---------- |Leaf|------| | | | | |---------+ +----+ | +------+ +-------| +-----+ | | | | | +--------------------------------+ | | +--------------------------------+ | | VPLS PE with T-VSI | | | | | +----+ | +------+ +-------+ +-----+ | PW | |Leaf|------|C-VLAN|---|S-VLAN |---|T-VSI|---------+ +----+ | | BRG | | BRG | | |---------- +----+ | | |---| |---| |---------- |Leaf|------| | | | | |---------- +----+ | +------+ +-------| +-----+ | | | +--------------------------------+ Figure 7 T-VSI interconnected with 1-side of pure Leaves Jiang, et al Expires April 25, 2011 [Page 12] Internet-Draft VPLS PE Model for E-Tree October 2010 6. LDP Extensions for E-Tree Support To dynamically provision the E-Tree service using the signaling procedures 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|R| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 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 R is a request bit of Remote VLAN Translation. If a PE is capable of translating VLANs, then set R to 0, otherwise set R to 1. If a PE receives R=1 from its peer, then it must do VLAN translation for this peer, otherwise local mapping rule applies. 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, together with its local root VLAN and leaf VLAN carried in the Root VLAN ID and Leaf VLAN ID field respectively. A PE that has E-Tree capability and willing to support it MUST include an E-Tree Sub-TLV with its own local root VLAN and leaf VLAN. A PE that is incapable of translating VLANs MUST set the R bit to 1, while a PE that is capable of translating VLANs MAY set the Jiang, et al Expires April 25, 2011 [Page 13] Internet-Draft VPLS PE Model for E-Tree October 2010 R bit to 1 to indicate remote mapping is preferred. And a PE is attached with pure leaves SHOULD set the P bit to 1. If a PE incapable of VLAN mapping has received an E-Tree Sub-TLV with the bit "R" set, and either the root VLAN ID or the leaf VLAN ID in the message does not match the local root VLAN or the local leaf VLAN, then the PW should not be set up and a label release message with the error code "E-Tree VLAN mapping not supported" must be sent. If a PE has sent an E-Tree Sub-TLV and has received an E-Tree Sub-TLV, then it must work as described in Section 5.3.1. If the bit "L" is set, then it should work as described in Section 5.3.3. If a PE has sent an E-Tree Sub-TLV and does not receive an E-Tree Sub-TLV, then it must work in the mode of compatibility as described in Section 5.3.2. 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 April 25, 2011 [Page 14] Internet-Draft VPLS PE Model for E-Tree October 2010 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-05, March 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-02, January 2010 [802.1aq] IEEE 802.1aq D3.0, Virtual Bridged Local Area Networks - Amendment 9: Shortest Path Bridging, June 2010 Jiang, et al Expires April 25, 2011 [Page 15] Internet-Draft VPLS PE Model for E-Tree October 2010 [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 April 25, 2011 [Page 16] Internet-Draft VPLS PE Model for E-Tree October 2010 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]) which may apply any transformation operation for VLANs (e.g., VLAN insertion/removal or VLAN mapping). Thus a root VLAN or leaf VLAN is added by the NSP depending on the UNI type of 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 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 April 25, 2011 [Page 17] Internet-Draft VPLS PE Model for E-Tree October 2010 Authors' Addresses Yuanlong Jiang Huawei Technologies Co., Ltd. Bantian industry base, Longgang district Shenzhen, China Email: yljiang@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 April 25, 2011 [Page 18]