INTERNET-DRAFT Sami Boutros Intended Status: Standard Track Ali Sajassi Samer Salam Cisco Systems John Drake Juniper Networks Jeff Tantsura Ericsson Dirk Steinberg Steinberg Consulting Expires: August 18, 2014 February 14, 2014 VPWS support in E-VPN draft-boutros-l2vpn-evpn-vpws-03.txt Abstract This document describes how E-VPN can be used to support virtual private wire service (VPWS) in MPLS/IP networks. E-VPN enables the following characteristics for VPWS: single-active as well as all- active multi-homing with flow-based load-balancing, eliminates the need for single-segment and multi-segment PW signaling, and provides fast protection using data-plane prefix independent convergence upon node or link failure. 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/1id-abstracts.html Boutros Expires August 18, 2014 [Page 1] INTERNET DRAFT VPWS support in E-VPN February 14, 2014 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Copyright and License 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. Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4 2. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 5 3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 6 5 ESI Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . 7 6 ESI value derivation and Eth-tag setting . . . . . . . . . . . . 7 7 VPWS with multiple sites . . . . . . . . . . . . . . . . . . . . 8 8 Security Considerations . . . . . . . . . . . . . . . . . . . . 8 9 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 10.1 Normative References . . . . . . . . . . . . . . . . . . . 8 10.2 Informative References . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Boutros Expires August 18, 2014 [Page 2] INTERNET DRAFT VPWS support in E-VPN February 14, 2014 1 Introduction This document describes how EVPN can be used to support virtual private wire service (VPWS) in MPLS/IP networks. The use of EVPN mechanisms for VPWS brings the benefits of EVPN to p2p services. These benefits include single-active redundancy as well as all-active redundancy with flow-based load-balancing. Furthermore, the use of EVPN for VPWS eliminates the need for signaling single-segment and multi-segment PWs for p2p Ethernet services. [EVPN] has the ability to forward customer traffic to/from a given customer Attachment Circuit (AC), aka Ethernet Segment in EVPN terminology, without any MAC lookup. This capability is ideal in providing p2p services (aka VPWS services). [MEF] defines Ethernet Virtual Private Line (EVPL) service as p2p service between a pair of ACs (designated by VLANs). EVPL can be considered as a VPWS with only two ACs. In delivering an EVPL service, the traffic forwarding capability of EVPN based on the exchange of a pair of Ethernet AD routes is used; whereas, for more general VPWS, traffic forwarding capability of EVPN based on the exchange of a group of Ethernet AD routes (one Ethernet AD route per AC/segment) is used. In a VPWS service, the traffic from an originating Ethernet Segment can be forwarded only to a single destination Ethernet Segment; hence, no MAC lookup is needed and the MPLS label associated with the per-EVI Ethernet AD route can be used in forwarding user traffic to the destination AC. In current PW redundancy mechanisms, convergence time is a function of control plane convergence characteristics. However, with EVPN it is possible to attain faster convergence through the use of data- plane prefix independent convergence, upon node or link failure. This document proposes the use of the Ethernet AD route to signal labels for P2P Ethernet services. As with EVPN, the Ethernet Segment route can be used to synchronize state between the PEs attached to the same multi-homed Ethernet Segment. 1.1 Terminology 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 RFC 2119 [RFC2119]. MAC: Media Access Control MPLS: Multi Protocol Label Switching. OAM: Operations, Administration and Maintenance. Boutros Expires August 18, 2014 [Page 3] INTERNET DRAFT VPWS support in E-VPN February 14, 2014 PE: Provide Edge Node. CE: Customer Edge device e.g., host or router or switch. EVI: EVPN Instance. Single-Active Mode: When a device or a network is multi-homed to two or more PEs and when only a single PE in such redundancy group can forward traffic to/from the multi-homed device or network for a given VLAN, then such multi-homing or redundancy is referred to as "Single- Active". All-Active: When a device is multi-homed to two or more PEs and when all PEs in such redundancy group can forward traffic to/from the multi-homed device for a given VLAN, then such multi-homing or redundancy is referred to as "All-Active". 1.2 Requirements 1. EPL service access circuit maps to the whole Ethernet port. 2. EVPL service access circuits are VLANs on single or double tagged trunk ports. Each VLAN individually will be considered to be an endpoint for an EVPL service, without any direct dependency on any other VLANs on the trunk. Other VLANs on the same trunk could also be used for EVPL services, but could also be associated with other services. 3. If multiple VLANs on the same trunk are associated with EVPL services, the respective remote endpoints of these EVPLs could be dispersed across any number of PEs, i.e. different VLANs may lead to different destinations. 4. The VLAN tag on the access trunk only has PE-local significance. The VLAN tag on the remote end could be different, and could also be double tagged when the other side is single tagged. 5. Also, multiple EVPL service VLANs on the same trunk could belong to the same EVPN instance (EVI), or they could belong to different EVIs. This should be purely an administrative choice of the network operator. 6. A given access trunk could have hundreds of EVPL services, and a given PE could have thousands of EVPLs configured. It must be possible to configure multiple EVPL services within the same EVI. 7. Local access circuits configured to belong to a given EVPN instance could also belong to different physical access trunks. Boutros Expires August 18, 2014 [Page 4] INTERNET DRAFT VPWS support in E-VPN February 14, 2014 2. BGP Extensions [EVPN] defines a new BGP NLRI for advertising different route types for EVPN operation. This document does not define any new BGP messages, but rather re-purposes one of the routes as described next. This document proposes the use of the per EVI Ethernet AD route to signal P2P services. The Ethernet Segment Identifier field is set to the ESI of the attachment circuit of the VPWS service instance. The Ethernet Tag field is set to 0 in the case of an Ethernet Private Wire service, and to the VLAN identifier associated with the service for Ethernet Virtual Private Wire service. The Route-Target (RT) extended community that identifies the VPN associated with the p2p EVPLs where each EVPL is identified by . 3 Operation The following figure shows an example of a P2P service deployed with EVPN. Ethernet Ethernet Native |<--------- EVPN Instance ----------->| Native Service | | Service (AC) | |<-PSN1->| |<-PSN2->| | (AC) | V V V V V V | | +-----+ +-----+ +-----+ +-----+ | +----+ | | PE1 |======|ASBR1|==|ASBR2|===| PE3 | | +----+ | |-------+-----+ +-----+ +-----+ +-----+-------| | | CE1| | | |CE2 | | |-------+-----+ +-----+ +-----+ +-----+-------| | +----+ | | PE2 |======|ASBR3|==|ASBR4|===| PE4 | | +----+ ^ +-----+ +-----+ +-----+ +-----+ ^ | Provider Edge 1 ^ Provider Edge 2 | | | | | | | | EVPN Inter-provider point | | | |<---------------- Emulated Service -------------------->| iBGP sessions are established between PE1, PE2, ASBR1 and ASBR3, possibly via a BGP route-reflector. Similarly, iBGP sessions are established between PE3, PE4, ASBR2 and ASBR4. eBGP sessions are established among ASBR1, ASBR2, ASBR3, and ASBR4. All PEs and ASBRs are enabled for the EVPN SAFI, and exchange EVPN Ethernet A-D routes - one route per AC. The ASBRs re-advertise the Ethernet A-D routes with Next Hop attribute set to their IP Boutros Expires August 18, 2014 [Page 5] INTERNET DRAFT VPWS support in E-VPN February 14, 2014 addresses. The link between the CE and the PE is either a C-tagged or S-tagged interface, as described in [802.1Q], that can carry a single VLAN tag or two nested VLAN tags. This interface is set up as a trunk with multiple VLANs. A VPWS with multiple sites or multiple EVPL services on the same CE port can be included in one EVI between 2 or more PEs. An Ethernet Tag corresponding to each P2P connection and known to both PEs is used to identify the services multiplexed in the same EVI. For CE single-homing the ESI field must be set to 0 in the Ethernet AD route, the field will be set to the AC-ID of the EVPL or EPL service. For CE multi-homing, the Ethernet AD Route encodes the ESI associated with the CE. This allows flow-based load-balancing of traffic between PEs connected to the same multi-homed CE. The AC ID encoded in the tag field MUST be the same on both PEs attached to the site. The Ethernet Segment route may be used too, for discovery of multi-homed CEs. In all cases traffic follows the transport paths, which may be asymmetric. The field of the EVI EAD route represents the AC-ID of the EPL and EVPL service. EPL service need to be identified by a non 0 field in the Ethernet AD route. The field value representing the AC-ID of the EPL/EVPL service of the remote side may be equal to the local side. An operator may choose to associate many per EVI EAD routes with different ESIs and tags to the same Route-Target (RT) extended community attribute. As such, the association of per EVI EAD routes to the same RT is a network operator design choice. Per ES EAD route can be used for mass withdraw to withdraw all per EVI EAD routes associated with the multi-home site on a given PE. The VLANs on the two ACs of a given EVPL service may have different VLANs. EVPN doesn't perform that translation, and that it should be handled by the Ethernet interface. 4 EVPN Comparison to PW Signaling In EVPN, service endpoint discovery and label signaling are done concurrently using BGP. Whereas, with VPWS based on [RFC4448], label signaling is done via LDP and service endpoint discovery is either Boutros Expires August 18, 2014 [Page 6] INTERNET DRAFT VPWS support in E-VPN February 14, 2014 through manual provisioning or through BGP. In existing implementation of VPWS using pseudowires(PWs), redundancy is limited to single-active mode, while with EVPN implementation of VPWS both single-active and all-active redundancy modes can be supported. In existing implementation with PWs, backup PWs are not used to carry traffic, while with EVPN, traffic can be load-balanced among different PEs multi-homed to a single CE. Upon link or node failure, EVPN can trigger failover with the withdrawal of a single BGP route per EVPL service or multiple EVPL services, whereas with VPWS PW redundancy, the failover sequence requires exchange of two control plane messages: one message to deactivate the group of primary PWs and a second message to activate the group of backup PWs associated with the access link. Finally, EVPN may employ data plane local repair mechanisms not available in VPWS. 5 ESI Bandwidth The ESI Bandwidth will be encoded using the Link Bandwidth Extended community defined in [draft-ietf-idr-link-bandwidth] and associated with the Ethernet AD route used to realize the EVPL services. When a PE receives this attribute for a given EVPL it MUST request the required bandwidth from the PSN towards the other EVPL service destination PE originating the message. When resources are allocated from the PSN for a given EVPL service, then the PSN SHOULD account for the Bandwidth requested by this EVPL service. In the case where PSN resources are not available, the PE receiving this attribute MUST re-send its local Ethernet AD routes for this EVPL service with the ESI Bandwidth = All FFs to declare that the "PSN Resources Unavailable". The scope of the ESI Bandwidth is limited to only one Autonomous System. 6 ESI value derivation and Eth-tag setting The ESI value is set per [EVPN] procedures - e.g., it is set to 0 for single home sites and can be manually configured or auto-derived for multi-homed sites. The field in the Ethernet A-D per EVI route is set to the AC-ID representing the EPL or EVPL service. This is different from Boutros Expires August 18, 2014 [Page 7] INTERNET DRAFT VPWS support in E-VPN February 14, 2014 the baseline [EVPN] Where field is set only for VLAN-aware bundle service. The AC-ID value SHOULD be the same at both sides of the EPL or EVPL service and it SHOULD be unique within an AS. "EVI" for VPWS services MUST be different from multipoint services specified in baseline [EVPN]. This implies the corresponding RTs for VPWS and multipoint services needs to be different. AC-IDs in the field MUST be unique within one AS, an ASBR MAY be required to perform AC-IDs translations if the AC-IDs are not unique across multiple ASs. Local and remote AC-IDs of a given EVPL or EPL service, are configured by an operator to connect the 2 sides of the EPL/EVPL services at both sides of the services. 7 VPWS with multiple sites The VPWS among multiple sites (full mesh of P2P connections - one per pair of sites) that can be setup automatically without any explicit provisioning of P2P connections among the sites is outside the scope of this document. 8 Security Considerations This document does not introduce any additional security constraints. 9 IANA Considerations TBD 10 References 10.1 Normative References [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 10.2 Informative References [EVPN-REQ] A. Sajassi, R. Aggarwal et. al., "Requirements for Ethernet VPN", draft-ietf-l2vpn-evpn-req-00.txt. [EVPN] A. Sajassi, R. Aggarwal et. al., "BGP MPLS Based Ethernet VPN", draft-ietf-l2vpn-evpn-04.txt. Boutros Expires August 18, 2014 [Page 8] INTERNET DRAFT VPWS support in E-VPN February 14, 2014 [PBB-EVPN] A. Sajassi et. al., "PBB-EVPN", draft-ietf-l2vpn-pbb-evpn- 05.txt. [draft-ietf-idr-link-bandwidth] P. Mohapatra, R. Fernando, "BGP Link Bandwidth Extended Community", draft-ietf-idr-link-bandwidth-06.txt Authors' Addresses Sami Boutros Cisco Email: sboutros@cisco.com Ali Sajassi Cisco Email: sajassi@cisco.com Samer Salam Cisco Email: ssalam@cisco.com John Drake Juniper Networks Email: jdrake@juniper.net Jeff Tantsura Ericsson Email: jeff.tantsura@ericsson.com Dirk Steinberg Steinberg Consulting Email: dws@steinbergnet.net Patrice Brissette Cisco Email: pbrisset@cisco.com Boutros Expires August 18, 2014 [Page 9]