INTERNET-DRAFT Sami Boutros Intended Status: Standard Track Ali Sajassi Samer Salam Cisco Systems John Drake Juniper Networks Jeff Tantsura Ericsson Expires: April 24, 2014 October 21, 2013 VPWS support in E-VPN draft-boutros-l2vpn-evpn-vpws-02.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 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Boutros Expires April 24, 2014 [Page 1] INTERNET DRAFT VPWS support in E-VPN October 21, 2013 Copyright and License Notice Copyright (c) 2013 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 2. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4 EVPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 5 5 ESI Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . 6 6 ESI value derivation . . . . . . . . . . . . . . . . . . . . . . 6 7 VPWS with multiple sites . . . . . . . . . . . . . . . . . . . . 6 8 Security Considerations . . . . . . . . . . . . . . . . . . . . 6 9 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 10 References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 10.1 Normative References . . . . . . . . . . . . . . . . . . . 7 10.2 Informative References . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Boutros Expires April 24, 2014 [Page 2] INTERNET DRAFT VPWS support in E-VPN October 21, 2013 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 April 24, 2014 [Page 3] INTERNET DRAFT VPWS support in E-VPN October 21, 2013 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". 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 is associated with a Route-Target (RT) extended community attribute that identifies the service instance (together with the Ethernet Tag field when non- zero). 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 | Boutros Expires April 24, 2014 [Page 4] INTERNET DRAFT VPWS support in E-VPN October 21, 2013 | |-------+-----+ +-----+ +-----+ +-----+-------| | +----+ | | 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 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 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 VPN ID 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. 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 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 primary and secondary PEs. Upon link or node failure, EVPN can trigger failover with the withdrawal of a single BGP route per service, Boutros Expires April 24, 2014 [Page 5] INTERNET DRAFT VPWS support in E-VPN October 21, 2013 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". 6 ESI value derivation The 10 bytes ESI value will contain:- 1) 6-byte System-ID that is globally unique. These 6 bytes can be auto derived using a mechanism similar to the one used for automating B-MAC Address Assignment in [PBB-EVPN]. 2) 4-byte Local-AC-ID that is unique within each PE. The combination of System-ID and Local-AC-ID makes the associated AC- ID globally unique. A pair of such globally unique AC-ID identifies a point-to-point service (EVPL or EPL) uniquely in the provider network. 7 VPWS with multiple sites The future revision of this draft will describe how a VPWS among multiple sites (full mesh of P2P connections - one per pair of sites) can be setup automatically without any explicit provisioning of P2P connections among the sites. 8 Security Considerations Boutros Expires April 24, 2014 [Page 6] INTERNET DRAFT VPWS support in E-VPN October 21, 2013 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. [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 170 West Tasman Drive San Jose, CA 95134, US Email: sboutros@cisco.com Ali Sajassi Cisco 170 West Tasman Drive San Jose, CA 95134, US Email: sajassi@cisco.com Samer Salam Cisco 595 Burrard Street, Suite 2123 Vancouver, BC V7X 1J1, Canada Email: ssalam@cisco.com Boutros Expires April 24, 2014 [Page 7] INTERNET DRAFT VPWS support in E-VPN October 21, 2013 John Drake Juniper Networks Email: jdrake@juniper.net Jeff Tantsura Ericsson Email: jeff.tantsura@ericsson.com Boutros Expires April 24, 2014 [Page 8]