INTERNET-DRAFT Sami Boutros Intended Status: Standard Track Ali Sajassi Samer Salam Cisco Systems John Drake Juniper Networks Jeff Tantsura Ericsson Expires: August 28, 2013 February 24, 2013 VPWS support in E-VPN draft-boutros-l2vpn-evpn-vpws-01.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: active/standby as well as active/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 August 28, 2013 [Page 1] INTERNET DRAFT VPWS support in E-VPN February 24, 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 E-VPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 5 5 ESI Bandwidth Attribute . . . . . . . . . . . . . . . . . . . . 5 6 VPWS with multiple sites . . . . . . . . . . . . . . . . . . . . 6 7 Security Considerations . . . . . . . . . . . . . . . . . . . . 6 8 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 9 References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 9.1 Normative References . . . . . . . . . . . . . . . . . . . 6 9.2 Informative References . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Boutros Expires August 28, 2013 [Page 2] INTERNET DRAFT VPWS support in E-VPN February 24, 2013 1 Introduction This document describes how E-VPN can be used to support virtual private wire service (VPWS) in MPLS/IP networks. The use of E-VPN mechanisms for VPWS applies the benefits of E-VPN to p2p services. These benefits include active/standby AC redundancy as well as active/active multi-homing with flow-based load-balancing. Furthermore, the use of E-VPN for VPWS eliminates the need for signaling single-segment and multi-segment PWs for p2p Ethernet services. [E-VPN] has the ability to forward customer traffic to/from a given customer Attachment Circuit (AC), aka Ethernet Segment in E-VPN terminology, without any MAC lookup. This capability is ideal in providing p2p services (aka VPWS services). [MEF] defines 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 E-VPN using only a pair of Ethernet AD routes is used; whereas, for more general VPWS, traffic forwarding capability of E-VPN using a group of Ethernet AD routes (one Ethernet AD route per AC/segment) is used. Since in VPWS services, the traffic from an originating Ethernet Segment can go only to a single destination Ethernet Segment, 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 E-VPN 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 E-VPN, the Ethernet Segment route can be used to synchronize state between the PEs attached to the same multi-homed 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. Boutros Expires August 28, 2013 [Page 3] INTERNET DRAFT VPWS support in E-VPN February 24, 2013 OAM: Operations, Administration and Maintenance. PE: Provide Edge Node. CE: Customer Edge device e.g., host or router or switch. EVI: E-VPN Instance. 2. BGP Extensions [E-VPN] defines a new BGP NLRI for advertising different route types for E-VPN 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 E-VPN. Ethernet Ethernet Native |<---------E-VPN 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 | | | | | | | | E-VPN Inter-provider point | | | |<---------------- Emulated Service -------------------->| Boutros Expires August 28, 2013 [Page 4] INTERNET DRAFT VPWS support in E-VPN February 24, 2013 iBGP sessions will be established between PE1, PE2, ASBR1 and ASBR3, possibly via a BGP route-reflector. Similarly, iBGP sessions will be established between PE3, PE4, ASBR2 and ASBR4. eBGP sessions will be established among ASBR1, ASBR2, ASBR3, and ASBR4. All PEs and ASBRs are enabled for the E-VPN SAFI, and exchange E-VPN 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 E-VPN Comparison to PW Signaling In E-VPN, 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 VPWS, redundancy is limited to Active/Standby mode, while with E-VPN both Active/Active and Active/Standby redundancy modes can be supported. In VPWS, backup PWs are not used to carry traffic, while E-VPN traffic can be load- balanced among primary and secondary PEs. On link or node failure, E- VPN can trigger failover with the withdrawal of a single BGP route per service, 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, E- VPN may employ data plane local repair mechanisms not available in VPWS. 5 ESI Bandwidth Attribute The ESI Bandwidth Attribute is a new optional BGP attribute that will be associated with the Ethernet AD route used to realize the EVPL services. Boutros Expires August 28, 2013 [Page 5] INTERNET DRAFT VPWS support in E-VPN February 24, 2013 +---------------------------------------+ | Type (2 octets) | +---------------------------------------+ | Length (2 octets) | +---------------------------------------+ | Flags (1 Octet) | +---------------------------------------+ | Reserved=0(1 Octet) | +---------------------------------------+ | Reverse SENDER_TSPEC | +---------------------------------------+ The content of the SENDER_TSPEC are as defined in [RFC 2210] section 3.1. When a PE receives this attribute for a given EVPL it MUST request the appropriate resources described in the SENDER_TSPEC 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 attribute and with the Flags set to 1 "PSN Resources Unavailable". 6 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. 7 Security Considerations This document does not introduce any additional security constraints. 8 IANA Considerations TBD 9 References 9.1 Normative References [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Boutros Expires August 28, 2013 [Page 6] INTERNET DRAFT VPWS support in E-VPN February 24, 2013 [RFC 2210] Wroclawski, J. "The Use of RSVP with IETF Integrated Services", RFC 2210, September 1997 9.2 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-00.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 John Drake Juniper Networks Email: jdrake@juniper.net Jeff Tantsura Ericsson Email: jeff.tantsura@ericsson.com Boutros Expires August 28, 2013 [Page 7]