Internet Working Group Y. Jiang L. Yong Internet Draft Huawei Intended status: Standards Track M. Paul Deutsche Telekom F. Jounay Orange CH F. Balus W. Henderickx Alcatel-Lucent A. Sajassi Cisco Expires: October 2014 April 8, 2014 Ethernet-Tree (E-Tree) Support in Virtual Private LAN Service (VPLS) draft-ietf-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 October 8, 2014. Jiang, et al Expires October 8, 2014 [Page 1] Internet-Draft E-Tree Support in VPLS April 2014 Copyright Notice Copyright (c) 2014 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. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Abstract A generic Virtual Private LAN Service (VPLS) solution is proposed for Ethernet-Tree (E-Tree) services which uses VLANs to indicate root or 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. Conventions used in this document ......................... 3 2. Terminology ............................................... 3 3. Introduction .............................................. 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. Signaling for E-Tree Support ............................. 14 6.1. LDP Extensions for E-Tree Support ..................... 14 6.2. BGP Extensions for E-Tree Support ..................... 16 7. OAM Considerations ....................................... 18 8. Applicability ............................................ 18 9. Security Considerations .................................. 18 Jiang, et al Expires October 8, 2014 [Page 2] Internet-Draft E-Tree Support in VPLS April 2014 10. IANA Considerations ...................................... 19 11. References ............................................... 19 11.1. Normative References ............................... 19 11.2. Informative References ............................. 20 12. Acknowledgments .......................................... 20 Appendix A. Other PE Models for E-Tree ........................ 21 A.1. A PE Model With a VSI and No bridge ................... 21 A.2. A PE Model With external E-Tree interface ............. 22 1. 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]. 2. Terminology E-Tree: Ethernet Tree, a Rooted-Multipoint EVC service as defined in MEF 6.1 EVC: Ethernet Virtual Connection, as defined in MEF 4.0 FIB: Forwarding Information Base, or forwarding table 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 C-VLAN, Customer VLAN S-VLAN, Service VLAN B-VLAN, Backbone VLAN 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 I-SID, Backbone Service Instance Identifier, as defined in IEEE 802.1ah Jiang, et al Expires October 8, 2014 [Page 3] Internet-Draft E-Tree Support in VPLS April 2014 3. Introduction The Ethernet-Tree (E-Tree) service is defined in Metro Ethernet Forum (MEF) as a Rooted-Multipoint Ethernet Virtual Connection (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 [802.1Q-2011], which is just an improvement on the traditional asymmetric VLAN mechanism (the use of different VLANs to indicate E-Tree root/leaf attributes and prohibiting leaf-to-leaf traffic with the help of VLANs was first standardized in IEEE 802.1Q- 2003). 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. Jiang, et al Expires October 8, 2014 [Page 4] Internet-Draft E-Tree Support in VPLS April 2014 This document introduces how the Ethernet VLAN solution can be used to support generic E-Tree services in VPLS. The solution proposed here is fully compatible with the IEEE bridge architecture and the IETF PWE3 technology, thus it will not change the FIB (such as installing E-Tree attributes in the FIB), or need any specially tailored implementation. Furthermore, 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. 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 VPLS. Finally, it describes the signaling extensions and processing procedures for E-Tree support in VPLS. 4. PE Model with E-Tree Support Problem scenario of E-Tree as shown in Fig. 1 of [Etree-req] is a simplification of the L2VPN architecture, several common VPLS PE architectures are discussed in more details in [RFC4664] and [RFC6246]. Therefore, E-Tree solution in VPLS is demonstrated with the help of a typical VPLS PE model. It can also be used by other PE models which are 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 Jiang, et al Expires October 8, 2014 [Page 5] Internet-Draft E-Tree Support in VPLS April 2014 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 +----------------------------------------+ | 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 Jiang, et al Expires October 8, 2014 [Page 6] Internet-Draft E-Tree Support in VPLS April 2014 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 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 to the roots and the leaves, while the frames with the leaf VLAN tag are transmitted to the roots but dropped for the leaves (these VLAN tags are removed before the frames are transmitted over the wire). It was demonstrated in [802.1Q-2011] 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. +----------------------------------------+ | 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 October 8, 2014 [Page 7] Internet-Draft E-Tree Support in VPLS April 2014 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 (frames over this port are untagged) or VLAN- unaware port (VLAN tags in the frames are ignored), the Ethernet frames received from the root ACs SHOULD be tagged with a root C-VLAN, and optionally MAY be added with another root S-VLAN. For a C-VLAN tagged port, the Ethernet frames received from the root ACs SHOULD be added with a root S-VLAN. For an S-VLAN tagged port, the S-VLAN tag in the Ethernet frames received from the root ACs SHOULD be translated to the root S-VLAN in the VPLS network domain. Alternatively, the PBB VPLS PE model (where an IEEE 802.1ah bridge module is embedded in the PE) as described in [PBB-VPLS] MAY be used, and a root B-VLAN or leaf B-VLAN MAY be added Jiang, et al Expires October 8, 2014 [Page 8] Internet-Draft E-Tree Support in VPLS April 2014 in this case (the E-Tree attribute may also be indicated with two I- SID tags in the bridge module, and the frames are further encapsulated and transported transparently over a single B-VLAN, thus the PBB VPLS works just in the same way as described in [PBB-VPLS] and will be discussed no more in this document). When many S-VLANs are multiplexed in a single AC, the 2nd option has an advantage of both VLAN scalability and MAC address scalability. 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 carried in each frame in the PW to indicate the frame originated from either root or leaf (the VLAN tag indicating the frame originated from either root or leaf can be translated by a bridge module in the PE or added by an outside Ethernet edge device, even by a customer device). 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 be used to carry E-Tree service for a PW in Compatible mode as shown in Section 5.3.2. 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 October 8, 2014 [Page 9] Internet-Draft E-Tree Support in VPLS April 2014 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]. Global or local VLANs can be manually configured or provisioned by an OSS system. Alternatively, some automatic VLAN allocation algorithm may be provided in the management plane, but it is out scope of this document. For both methods, VLAN mapping parameters from a remote PE can be provisioned or determined by a signaling protocol as described in Section 6 when a PW is being established. Jiang, et al Expires October 8, 2014 [Page 10] Internet-Draft E-Tree Support in VPLS April 2014 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 both root and leaf nodes). +------------------------+ | 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 [802.1Q-2011]. Jiang, et al Expires October 8, 2014 [Page 11] Internet-Draft E-Tree Support in VPLS April 2014 The signaling for VLANs is specified in Section 6. 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. A raw PW should be used to connect them. +------------------------+ | 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 process the frame as follows: o Upon transmitting frames on the PW, remove the root or leaf VLAN in the frames. o Upon receiving frames on the PW, add a VLAN tag with a value of the local root VLAN to the frames. Jiang, et al Expires October 8, 2014 [Page 12] Internet-Draft E-Tree Support in VPLS April 2014 5.3.3.PW Processing in the Optimized Mode When two PEs (both have E-Tree capability) are inter-connected and one of them (e.g., PE2) is attached with only leaf nodes, as shown in the scenario of Fig. 7, its peer PE (e.g., PE1) should then work in the optimized 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 leaf nodes 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 PE attached with only leaf nodes If a PE is in the Optimized Mode for a PW, 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 October 8, 2014 [Page 13] Internet-Draft E-Tree Support in VPLS April 2014 6. Signaling for E-Tree Support 6.1. 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 leaf nodes, 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 leaf nodes SHOULD set the P bit to 1. Jiang, et al Expires October 8, 2014 [Page 14] Internet-Draft E-Tree Support in VPLS April 2014 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, after saving the VLAN information for the PW, 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 a status code "Leaf to Leaf PW released" 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, The PE SHOULD then Jiang, et al Expires October 8, 2014 [Page 15] Internet-Draft E-Tree Support in VPLS April 2014 establish a raw PW with this peer as in traditional VPLS and set Compatible-Mode to TRUE for this PW. Data plane processing for this PW is as following: If Optimized-Mode is TRUE, then data plane processing as described in Section 5.3.3 applies. If VLAN-Mapping-Mode is TRUE, then data plane processing as described in Section 5.3.1 applies. If Compatible-Mode is TRUE, then data plane processing is as described in Section 5.3.2. PW processing as described in [RFC4448] proceeds as usual for all cases. 6.2. BGP Extensions for E-Tree Support A new E-Tree extended community is proposed for E-Tree signaling in BGP VPLS: +------------------------------------+ | Extended community type (2 octets) | +------------------------------------+ | Root VLAN (2 octets) | +------------------------------------+ | Leaf VLAN (2 octets) | +------------------------------------+ | Reserved |P|V| +------------------------------------+ Figure 9 E-Tree Extended Community Where: o Root VLAN ID is the value of the local root VLAN. o Leaf VLAN ID is the value of the local leaf VLAN. o Reserved, 14 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 leaf nodes, and set to 0 otherwise. Jiang, et al Expires October 8, 2014 [Page 16] Internet-Draft E-Tree Support in VPLS April 2014 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. The PEs attached with both leaf and root nodes MUST support BGP E- Tree signaling as described in this document, and SHOULD support VLAN mapping in their data planes. The traditional PE attached with only root nodes may also participate in an E-Tree service. If some PEs don't support VLAN mapping, global VLANs as per Section 5.2 MUST be provisioned for an E-Tree service. In BGP VPLS signaling, besides attaching a Layer2 Info Extended Community as detailed in [RFC4761], an E-Tree Extended Community MUST be further attached if a PE wishes to participate in an E-Tree service. The PE MUST include its local root VLAN ID and leaf VLAN ID in the E-Tree Extended Community. A PE attached with only leaf nodes of an E-Tree SHOULD set the P bit in the E-Tree Extended Community to 1. A PE that receives a BGP UPDATE message with an E-Tree Extended Community from its peer PE, after saving the VLAN information for the PW, must process it as follows (after processing procedures as specified in Section 3.2 of [RFC4761]): 1) if the root and leaf VLAN ID in the E-Tree Extended Community 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 { Log with a message "E-Tree VLAN mapping not supported" and exit the process; } if the bit V is set, and the PE is capable of VLAN mapping, the PE with the minimum IP address MUST set VLAN-Mapping-Mode to TRUE; } 3) If the P bit is set { Jiang, et al Expires October 8, 2014 [Page 17] Internet-Draft E-Tree Support in VPLS April 2014 If the PE is a leaf-only PE itself, then forbids any traffic on the PW; Else the PE SHOULD set the Optimized-Mode to TRUE. } A PE which does not recognize this attribute shall ignore it silently. If a PE has sent an E-Tree Extended Community but does not receive any E-Tree Extended Community from its peer, the PE SHOULD then establish a raw PW with this peer as in traditional VPLS, and set Compatible-Mode to TRUE for this PW. Data plane in the VPLS is the same as described in Section 4.2 of [RFC4761], and data plane processing for a PW is the same as described at the end of Section 6.1. 7. OAM Considerations VPLS OAM requirements and framework as specified in [RFC6136] are applicable to E-Tree, as both Ethernet OAM frames and data traffic are transported over the same PW. Ethernet OAM for E-Tree including both service OAM and segment OAM frames shall undergo the same VLAN mapping as the data traffic; and root VLAN SHOULD be applied to segment OAM frames so that they are not filtered. 8. Applicability The solution is applicable to both LDP VPLS [RFC4762] and 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], [RFC4761] 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. Jiang, et al Expires October 8, 2014 [Page 18] Internet-Draft E-Tree Support in VPLS April 2014 10. IANA Considerations IANA is requested to allocate a value for E-Tree in the registry of Pseudowire Interface Parameters Sub-TLV type. Parameter ID Length Description ======================================= TBD 8 E-Tree IANA is requested to allocate two new LDP status codes from the registry of name "STATUS CODE NAME SPACE". The following values are suggested: Range/Value E Description ------------- ----- ---------------------- TBD 1 E-Tree VLAN mapping not supported TBD 0 Leaf to Leaf PW released IANA is requested to allocate a value for E-Tree in the registry of BGP Extended Community. Type Value Name ======================================= TBD E-Tree Info 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. [RFC4761] Kompella, K. and Rekhter, Y., "Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, January 2007 Jiang, et al Expires October 8, 2014 [Page 19] Internet-Draft E-Tree Support in VPLS April 2014 [RFC4762] Lasserre, M. and Kompella, V., "Virtual Private LAN Services using LDP", RFC 4762, January 2007. [RFC6136] Sajassi, A. and Mohan, D., "L2VPN OAM Requirements and Framework", RFC 6136, March 2011 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 Metro Ethernet Forum (MEF) Ethernet-Tree (E-Tree) Support in Layer 2 Virtual Private Network (L2VPN)", RFC 7152, March 2014 [ETree-frwk] Key, R., and et al, "A Framework for E-Tree Service over MPLS Network", draft-ietf-l2vpn-etree-frwk-04, Work in Progress [802.1Q-2011] IEEE 802.1Q, Media Access Control (MAC) Bridges and Virtual Bridge Local Area Networks, August 2011 [PBB-VPLS] Balus, F., and et al., Extensions to VPLS PE model for Provider Backbone Bridging, draft-ietf-l2vpn-pbb-vpls-pe- model-07, Work in Progress 12. Acknowledgments The authors would like to thank Adrian Farrel, Susan Hares and Shane Amante for their valuable advices, thank Ben Mack-crane, Edwin Mallette, Donald Fedyk, Dave Allan, Giles Heron, Raymond Key, Josh Rogers, Sam Cao and Daniel Cohn for their valuable comments and discussions. Jiang, et al Expires October 8, 2014 [Page 20] Internet-Draft E-Tree Support in VPLS April 2014 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 This PE model may be used by an MTU-s in an H-VPLS network, or an N- PE in an H-VPLS network with non-bridging edge devices, wherein a spoke PW can be treated as an AC in this model. Jiang, et al Expires October 8, 2014 [Page 21] Internet-Draft E-Tree Support in VPLS April 2014 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 or indirectly over a single PW connected to a same VSI forwarder in a PE, any transformation of E-Tree VLANs, e.g., VLAN insertion/removal or VLAN mapping, can be performed by some outer equipments, and the PE may further translate these VLANs into its own local VLANs. This PE model may be used by an N-PE in an H-VPLS network with bridging-capable devices, or scenarios such as providing E-Tree Network-to-Network (NNI) interfaces. Jiang, et al Expires October 8, 2014 [Page 22] Internet-Draft E-Tree Support in VPLS April 2014 Authors' Addresses Yuanlong Jiang Huawei Technologies Co., Ltd. Bantian, Longgang district Shenzhen 518129, China Email: jiangyuanlong@huawei.com Lucy Yong Huawei USA 207 Estrella Xing Georgetown TX, USA 78628 Email: lucyyong@huawei.com Manuel Paul Deutsche Telekom Winterfeldtstr. 21 10781 Berlin, Germany Email: manuel.paul@telekom.de Frederic Jounay Orange CH 4 rue caudray 1020 Renens, Switzerland Email: frederic.jounay@orange.ch 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 Ali Sajassi Cisco 170 West Tasman Drive San Jose, CA 95134, USA Email: sajassi@cisco.com Jiang, et al Expires October 8, 2014 [Page 23]