Network Working Group Y. Jiang, Ed. Internet Draft L. Yong Intended status: Standards Track Huawei M. Paul Deutsche Telekom Expires: March 2016 September 23, 2015 Ethernet-Tree (E-Tree) Support in Virtual Private LAN Service (VPLS) draft-ietf-l2vpn-vpls-pe-etree-09.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." 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Jiang, et al Expires March 23, 2016 [Page 1] Internet-Draft E-Tree Support in VPLS September 2015 Abstract This document specifies a generic Virtual Private LAN Service (VPLS) solution which uses VLANs to indicate root or leaf traffic to support Ethernet-Tree (E-Tree) services. A VPLS Provider Edge (PE) model is illustrated as an example for the solution. In the solution, E-Tree VPLS PEs are interconnected by Pseudo Wires (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 specified in RFC 4762 and RFC 4448 respectively. A signaling mechanism is described to support E-Tree capability and VLAN mapping negotiation. 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 .......................................... 10 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 .................................. 19 10. IANA Considerations ...................................... 19 11. References ............................................... 19 11.1. Normative References ............................... 19 11.2. Informative References ............................. 20 12. Acknowledgments .......................................... 21 Appendix A. Other PE Models for E-Tree ........................ 22 A.1. A PE Model With a VSI and No bridge ................... 22 A.2. A PE Model With external E-Tree interface ............. 23 Jiang, et al Expires March 23, 2016 [Page 2] Internet-Draft E-Tree Support in VPLS September 2015 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 AC: Attachment Circuit B-VLAN: Backbone VLAN C-VLAN: Customer VLAN E-Tree: Ethernet Tree, a Rooted-Multipoint EVC service as defined in [MEF6.1] EVC: Ethernet Virtual Connection, as defined in [MEF4] FIB: Forwarding Information Base, also known as forwarding table I-SID: Backbone Service Instance Identifier, as defined in IEEE 802.1ah Leaf AC: an AC attached with a leaf Leaf VLAN: a VLAN Identifier (ID) used to indicate all the frames that are originated at a leaf AC, it may be a C-VLAN, an S-VLAN or a B-VLAN OAM: Operations, Administration and Maintenance PBB: Provider Backbone Bridge PE: Provider Edge PW: Pseudo Wire Root AC: an AC attached with a root Root VLAN: a VLAN ID used to indicate all the frames that are originated at a root AC, it may be a C-VLAN, an S-VLAN or a B-VLAN S-VLAN: Service VLAN T-VSI: Tree VSI, a VSI with E-Tree support VLAN: Virtual Local Area Network Jiang, et al Expires March 23, 2016 [Page 3] Internet-Draft E-Tree Support in VPLS September 2015 VPLS: Virtual Private LAN Service VSI: Virtual Switching Instance as defined in [RFC4664], also known as VPLS Forwarder in [RFC7041] 3. Introduction The Ethernet-Tree (E-Tree) service is defined in Metro Ethernet Forum (MEF) Technical Specification MEF 6.1 as a Rooted-Multipoint Ethernet Virtual Connection (EVC) service. It is a multipoint Ethernet service with special restrictions: the Ethernet 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 Virtual Private Multicast Service (VPMS) [VPMS] or Point-to-Multipoint (P2MP) multicast is a somewhat simplified version of this service, in fact, they are both multicast services and are different from an E-Tree service which may include both unicast and multicast traffic. [RFC7152] gives the requirements for providing E-Tree solutions in the VPLS and the need to filter leaf-to-leaf traffic. [RFC7387] further describes a Multiprotocol Label Switching (MPLS) framework for providing E-Tree. Though there were proposals on using the Pseudowire (PW) control word or PWs to indicate the root/leaf attribute of an E-Tree frame, both methods are limited in that they are only applicable to "VPLS only" networks. A VPLS PE usually consists of a bridge module itself (see [RFC4664] and [RFC6246]); and 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 into 802.1Q [802.1Q-2014], which is an improvement on the traditional asymmetric VLAN mechanism. In the asymmetric VLAN mechanism as described in Section B.1.3 of IEEE 802.1Q-2003, a VLAN ID is used to indicate the traffic from a server, and multiple VLAN IDs are used to indicate the traffic from the clients (one VLAN ID per client). In the new IEEE 802.1Q solution, only two VLANs are used to indicate root/leaf attributes of a frame: 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. A new mechanism would introduce more complexity to interwork with the new IEEE 802.1Q solution. Jiang, et al Expires March 23, 2016 [Page 4] Internet-Draft E-Tree Support in VPLS September 2015 This document specifies how the Ethernet VLAN solution can be used to support generic E-Tree services in VPLS. The solution specified here is fully compatible with the IEEE bridge architecture and with IETF Pseudo Wire Emulation Edge-to-Edge (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 are also maintained. With this mechanism, it is also convenient to deploy a converged E-Tree service across both Ethernet and MPLS networks. 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. The document then discusses the PW encapsulation and PW processing such as VLAN mapping options for transporting E-Tree services in VPLS. Finally, the document describes the signaling extensions and processing procedures for E-Tree support in VPLS. 4. PE Model with E-Tree Support The problem scenario of E-Tree as shown in Fig. 1 of [RFC7152] is a simplification of the L2VPN architecture, several common VPLS PE architectures are discussed in more details in [RFC4664] and [RFC6246]. Below, an E-Tree solution in VPLS is demonstrated with the help of a typical VPLS PE model. Its use in other PE models 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 (both figures are extracted from Jiang, et al Expires March 23, 2016 [Page 5] Internet-Draft E-Tree Support in VPLS September 2015 [RFC6246]), where an S-VLAN bridge module is connected to multiple VSIs each with a single VLAN virtual interface. +-------------------------------+ | 802.1ad Bridge Module Model | | | +---+ AC | +------+ +-----------+ | |CE |---------|C-VLAN|------| | | +---+ | |bridge|------| | | | +------+ | | | | o | S-VLAN | | | o | | | ---> to VSI | o | Bridge | | +---+ AC | +------+ | | | |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 bridge) and a VSI in a PE before being sent on the PW to a remote PE. Jiang, et al Expires March 23, 2016 [Page 6] Internet-Draft E-Tree Support in VPLS September 2015 Therefore, the association between an AC port and a PW on a VSI is difficult. This model could be further enhanced: When Ethernet frames arrive at an ingress PE, a root VLAN or a leaf VLAN tag is added. At an egress PE, 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 ACs). 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 March 23, 2016 [Page 7] Internet-Draft E-Tree Support in VPLS September 2015 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 specified. 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 AC port (frames over this port are untagged) or VLAN-unaware port (VLAN tags in the frames are ignored), and the bridge module is a C-VLAN bridge, the Ethernet frames received from the root ACs MUST be tagged with a root C-VLAN. When the bridge module is an 802.1ad bridge, the Ethernet frames received from the root ACs MUST be tagged with a root S-VLAN. Note, this can be done by adding a root C-VLAN first in a C-VLAN bridge but this is out of the scope of this document. For a C-VLAN tagged port, the Ethernet frames received from the root ACs MUST be tagged with a root S-VLAN. Jiang, et al Expires March 23, 2016 [Page 8] Internet-Draft E-Tree Support in VPLS September 2015 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, for an S-VLAN tagged port, the PBB VPLS PE model (where an IEEE 802.1ah bridge module is embedded in the PE) as described in [RFC7041] MAY be used. A root B-VLAN or leaf B-VLAN MAY be added. The E-Tree attribute may also be indicated with two I-SID tags in the bridge module, and the frames are then encapsulated and transported transparently over a single B-VLAN. Thus the PBB VPLS works in the same way as described in [RFC7041] and will not be discussed further in this document. When many S-VLANs are multiplexed in a single AC, PBB VPLS has the advantages 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 resulting Ethernet header is used to indicate the E-Tree attribute of an Ethernet frame; this document uses 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 SHOULD work in the tagged mode (PW type 0x0004) as described in [RFC4448], in which case 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. A raw mode PW (PW type 0x0005 in [RFC4448]) MAY also be used to carry E-Tree service for a PW in Compatible mode as shown in Section 5.3.2. As defined in [RFC4448], for a raw mode PW, an Ethernet frame's 802.1Q VLAN tag is not meaningful to the PEs and it passes transparently through them. Jiang, et al Expires March 23, 2016 [Page 9] Internet-Draft E-Tree Support in VPLS September 2015 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. 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 Operational Support System. Alternatively, some automatic VLAN allocation algorithm may be provided in the management plane, but it is out of 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 March 23, 2016 [Page 10] Internet-Draft E-Tree Support in VPLS September 2015 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 attached with both root and leaf nodes). +----------------------------+ | VPLS PE with T-VSI | | | +----+ | +------+ Root VLAN +-----+ | PW |Root|------| VLAN |-----------|T-VSI|---------- +----+ | | BRG | Leaf VLAN | |---------- +----+ | | |-----------| |---------- |Leaf|------| | | |-----+ +----+ | +------+ +-----+ | | | | | +----------------------------+ | | +----------------------------+ | | VPLS PE with T-VSI | | | | | +----+ | +------+ Root VLAN +-----+ | | PW |Root|------| VLAN |-----------|T-VSI|-----+ +----+ | | BRG | Leaf VLAN | |---------- +----+ | | |-----------| |---------- |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]. The signaling for VLANs used by E-Tree is specified in Section 6. Jiang, et al Expires March 23, 2016 [Page 11] Internet-Draft E-Tree Support in VPLS September 2015 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 March 23, 2016 [Page 12] Internet-Draft E-Tree Support in VPLS September 2015 5.3.3.PW Processing in the Optimized Mode When two PEs (both have E-Tree capability) are inter-connected with a PW 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 for this PW. 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 March 23, 2016 [Page 13] Internet-Draft E-Tree Support in VPLS September 2015 6. Signaling for E-Tree Support 6.1. LDP Extensions for E-Tree Support In addition to the signaling procedures as specified in Section 5.3.3 of [RFC4447], this document specifies 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(0x1A) | 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 (0x1A) as 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 peer 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 attached with only leaf nodes SHOULD set the P bit to 1. Jiang, et al Expires March 23, 2016 [Page 14] Internet-Draft E-Tree Support in VPLS September 2015 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) For this PW, set VLAN-Mapping-Mode, Compatible-Mode, and Optimized-Mode to FALSE. 2) If either the root VLAN ID in the message is not equal to the local root VLAN ID or the leaf VLAN ID in the message is not equal to the local leaf VLAN ID { If the bit V is cleared { If the PE is capable of VLAN mapping, 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, the PE with the minimum IP address MUST set VLAN-Mapping-Mode to TRUE; } 3) If the P bit is set { If the PE is a leaf-only node itself, 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. } A PE SHOULD send a Label Mapping message with an E-Tree Sub-TLV as per Section 5.3.3 of [RFC4447]. A PE MUST send a Label Mapping message with an updated E-Tree Sub-TLV to all other PEs over corresponding LDP sessions when its role changes from leaf-only to Jiang, et al Expires March 23, 2016 [Page 15] Internet-Draft E-Tree Support in VPLS September 2015 not leaf-only (i.e., when a root node is added to a PE attached with only leaf nodes). If a PE has sent a Label Mapping message with 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 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 (0x800b) is allocated by IANA 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. Jiang, et al Expires March 23, 2016 [Page 16] Internet-Draft E-Tree Support in VPLS September 2015 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. 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) For this PW, set VLAN-Mapping-Mode, Compatible-Mode, and Optimized-Mode to FALSE. 2) If either the root VLAN ID in the E-Tree Extended Community is not equal to the local root VLAN ID or the leaf VLAN ID in the E- Tree Extended Community is not equal to the local leaf VLAN ID { If the bit V is cleared { If the PE is capable of VLAN mapping, it MUST set VLAN- Mapping-Mode to TRUE; Else { Log with a message "E-Tree VLAN mapping not supported" and exit the process; } Jiang, et al Expires March 23, 2016 [Page 17] Internet-Draft E-Tree Support in VPLS September 2015 } 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 { If the PE is a leaf-only PE itself, 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 in this document. 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 specified in this document is applicable to both LDP VPLS [RFC4762] and BGP VPLS [RFC4761]. This solution is applicable to both "VPLS Only" networks and VPLS with Ethernet aggregation networks. This solution is also applicable to PBB VPLS networks. Jiang, et al Expires March 23, 2016 [Page 18] Internet-Draft E-Tree Support in VPLS September 2015 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. 10. IANA Considerations IANA allocated a value for E-Tree in the registry of Pseudowire Interface Parameters Sub-TLV type. Parameter ID Length Description ======================================= 0x1A 8 E-Tree IANA allocated two new LDP status codes from the registry of name "STATUS CODE NAME SPACE". Range/Value E Description ------------- ----- ---------------------- 0x20000003 1 E-Tree VLAN mapping not supported 0x20000004 0 Leaf to Leaf PW released IANA allocated a value for E-Tree in the registry of BGP Extended Community. Type Value Sub-Type Value Name ========== ============== ============ 0x80 0x0b 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., Rosen, E., El-Aawar, N., Smith, T., and Heron, G., "Pseudowire Setup and Maintenance Using Label Distribution Protocol (LDP)", RFC 4447, April 2006. Jiang, et al Expires March 23, 2016 [Page 19] Internet-Draft E-Tree Support in VPLS September 2015 [RFC4448] Martini, L., Rosen, E., El-Aawar, N., and Heron,G., "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. [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. [RFC6136] Sajassi, A. and Mohan, D., "L2VPN OAM Requirements and Framework", RFC 6136, March 2011. [RFC6246] Sajassi, A., Brockners, F., Mohan, D., and Serbest, Y., "Virtual Private LAN Service (VPLS) Interoperability with Customer Edge (CE) Bridges", RFC 6246, June 2011. [RFC7041] Balus, F., Sajassi, A., and Bitar, N., Extensions to VPLS PE model for Provider Backbone Bridging, RFC 7041, November 2013. [RFC7152] Key, R., DeLord, S., Jounay, F., Huang, L., Liu, Z., and M. Paul, "Requirements for Metro Ethernet Forum (MEF) Ethernet-Tree (E-Tree) Support in Layer 2 Virtual Private Network (L2VPN)", RFC 7152, March 2014. [RFC7387] Key, R., Yong, L., DeLord, S., Jounay, F., and Jin, L., "A Framework for Ethernet Tree (E-Tree) Service over a Multiprotocol Label Switching (MPLS) Network", RFC 7387, October 2014. [802.1Q-2014] IEEE Std 802.1Q-2014, Bridges and Bridged Networks, November 2014. [MEF4] Metro Ethernet Forum, Metro Ethernet Network Architecture Framework - Part 1: Generic Framework, Technical Specification MEF 4, May 2004. Jiang, et al Expires March 23, 2016 [Page 20] Internet-Draft E-Tree Support in VPLS September 2015 [MEF6.1] Metro Ethernet Forum, "Ethernet Services Definitions - Phase 2", Technical Specification MEF 6.1, April 2008. [VPMS] Kamite, Y., Jounay, F., Niven-Jenkins, B., Brungard, D., and L. Jin, "Framework and Requirements for Virtual Private Multicast Service (VPMS)", Work in Progress, draft-ietf-l2vpn-vpms-frmwk-requirements-05, October 2012. 12. Acknowledgments The authors would like to thank Stewart Bryant, Lizhong Jin and Deborah Brungard for their detailed reviews and suggestions, 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 March 23, 2016 [Page 21] Internet-Draft E-Tree Support in VPLS September 2015 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 User Network Interface (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 a Multi-Tenant Unit switch (MTU-s) in a Hierarchical VPLS (H-VPLS) network, or a Network-facing PE (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 March 23, 2016 [Page 22] Internet-Draft E-Tree Support in VPLS September 2015 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 interfaces. Jiang, et al Expires March 23, 2016 [Page 23] Internet-Draft E-Tree Support in VPLS September 2015 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 March 23, 2016 [Page 24]