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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 INTERNET-DRAFT Sami Boutros 3 Intended Status: Informational Ali Sajassi 4 Samer Salam 5 Expires: January 1, 2013 June 30, 2012 7 VPWS support in E-VPN 8 draft-boutros-l2vpn-evpn-vpws-00.txt 10 Abstract 12 This document describes how E-VPN can be used to support virtual 13 private wire service (VPWS) in MPLS/IP networks. E-VPN enables the 14 following characteristics for VPWS: 1) active/standby redundancy, 2) 15 active/active multi-homing with flow-based load-balancing, 3) 16 eliminates the need for single-segment and multi-segment PW 17 signaling, and 4) provides faster convergence using data-plane prefix 18 independent convergence upon node or link failure in comparison to 19 control-plane convergence with PW redundancy. 21 Status of this Memo 23 This Internet-Draft is submitted to IETF in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF), its areas, and its working groups. Note that 28 other groups may also distribute working documents as 29 Internet-Drafts. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 The list of current Internet-Drafts can be accessed at 37 http://www.ietf.org/1id-abstracts.html 39 The list of Internet-Draft Shadow Directories can be accessed at 40 http://www.ietf.org/shadow.html 42 Copyright and License Notice 44 Copyright (c) 2012 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (http://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 60 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 61 2. BGP Extensions . . . . . . . . . . . . . . . . . . . . . . . . 4 62 3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 63 4 E-VPN Comparison to PW Signaling . . . . . . . . . . . . . . . . 5 64 5 VPWS with multiple sites . . . . . . . . . . . . . . . . . . . . 5 65 6 Security Considerations . . . . . . . . . . . . . . . . . . . . 6 66 7 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 67 8 References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 68 8.1 Normative References . . . . . . . . . . . . . . . . . . . 6 69 8.2 Informative References . . . . . . . . . . . . . . . . . . 6 70 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 72 1 Introduction 74 This document describes how E-VPN can be used to support virtual 75 private wire service (VPWS) in MPLS/IP networks. The use of E-VPN 76 mechanisms for VPWS introduces all the benefits of E-VPN to p2p 77 services. These benefits include active/standby AC redundancy, 78 active/active multi-homing with flow-based load-balancing. 79 Furthermore, the use of E-VPN for VPWS eliminates the need for 80 signaling single-segment and multi-segment PWs for p2p Ethernet 81 services. 83 [E-VPN] has the ability to forward customer traffic to/from a given 84 customer Attachment Circuit (aka Ethernet AD route) without any MAC 85 lookup. This capability is ideal in providing P2P services (aka VPWS 86 services). [MEF] defines EVPL service as P2P service between a pair 87 of ACs (designated by VLANs). EVPL can be considered as a VPWS with 88 only two ACs. In delivering an EVPL service, traffic forwarding 89 capability of E-VPN between a pair of Ethernet AD routes is used; 90 whereas, for more general VPWS, traffic forwarding capability of E- 91 VPN among a group of Ethernet AD routes (one Ether AD route per 92 AC/site) is used. Since in VPWS services, the traffic from an 93 originating Ether AD route can go only to a single destination Ether 94 AD route, no MAC lookup is needed and MPLS label associated with the 95 destination Ether AD route can be used in forwarding user traffic to 96 the destination AC. 98 In current PW redundancy mechanisms, convergence time is a function 99 of control plane convergence characteristics. However, with E-VPN it 100 is possible to attain faster convergence through the use of data- 101 plane prefix independent convergence upon node or link failure. 103 This document proposes the use of the Ethernet AD route to signal 104 labels for P2P Ethernet services. As with E-VPN, the Ethernet Segment 105 route can be used to synchronize LACP and other state between the PEs 106 attached to the same multi-homed device. 108 1.1 Terminology 110 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 111 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 112 document are to be interpreted as described in RFC 2119 [RFC2119]. 114 MAC: Media Access Control 116 MPLS: Multi Protocol Label Switching. 118 OAM: Operations, Administration and Maintenance. 120 PE: Provide Edge Node. 122 CE: Customer Edge device e.g., host or router or switch. 124 EVI: E-VPN Instance. 126 2. BGP Extensions 128 [E-VPN] defines a new BGP NLRI for advertising different route types 129 for E-VPN operation. This document does not define any new BGP 130 messages, but rather repurposes one of the routes as described next. 132 This document proposes the use of the Ethernet AD route to signal P2P 133 services. The Ethernet Segment Identifier field is set to the ESI of 134 the attachment circuit of the VPWS service instance. The Ethernet Tag 135 field is set to 0 in the case of an Ethernet Private Wire service, 136 and to the VLAN identifier associated with the service for Ethernet 137 Virtual Private Wire service. The route is associated with a Route- 138 Target (RT) extended community attribute that identifies the service 139 instance (together with the Ethernet Tag field when non-zero 141 3 Operation 143 The following figure shows an example of a P2P service deployed with 144 E-VPN. 145 Ethernet Ethernet 146 Native |<---------E-VPN Instance------------>| Native 147 Service | | Service 148 (AC) | |<-PSN1->| |<-PSN2->| | (AC) 149 | V V V V V V | 150 | +-----+ +-----+ +-----+ +-----+ | 151 +----+ | | PE1 |======|ASBR1|==|ASBR2|===| PE3 | | +----+ 152 | |-------+-----+ +-----+ +-----+ +-----+-------| | 153 | CE1| | | |CE2 | 154 | |-------+-----+ +-----+ +-----+ +-----+-------| | 155 +----+ | | PE2 |======|ASBR3|==|ASBR4|===| PE4 | | +----+ 156 ^ +-----+ +-----+ +-----+ +-----+ ^ 157 | Provider Edge 1 ^ Provider Edge 2 | 158 | | | 159 | | | 160 | E-VPN Inter-provider point | 161 | | 162 |<---------------- Emulated Service -------------------->| 164 iBGP sessions will be established between PE1, PE2, ASBR1 and ASBR3, 165 possibly via a BGP route-reflector. Similarly, iBGP sessions will be 166 established between PE3, PE4, ASBR2 and ASBR4. eBGP sessions will be 167 established among ASBR1, ASBR2, ASBR3, and ASBR4. 169 All PEs and ASBRs are enabled for the E-VPN SAFI, and exchange E-VPN 170 Ethernet A-D routes - one route per AC. The ASBRs re-advertise the 171 Ethernet A-D routes with Next Hop attribute set to their IP 172 addresses. The link between the CE and the PE is an C-TAG or S-TAG 173 interface as described in [802.1Q] that can carry a single vlan tag 174 or two vlan tags nested in each other. This interface is setup as a 175 trunk with multiple VLANs. 177 A VPWS with multiple sites or multiple EVPL services on the same CE 178 port can be included in one EVI between 2 or more PEs. An Ethernet 179 Tag corresponding to each P2P connection and known to both PEs is 180 used to identify the services multiplexed in the same EVI. For CE 181 multi-homing, the Ethernet AD Route encodes the ESI associated with 182 the CE. This allows flow-based load-balancing of traffic between PEs 183 connected to the same multi-homed CE. The VPN ID MUST be the same on 184 both PEs attached to the site. The Ethernet Segment route may be used 185 too, for discovery of multi-homed CEs. In all cases traffic follows 186 the transport paths, which may be asymmetric. 188 4 E-VPN Comparison to PW Signaling 190 In E-VPN, service endpoint discovery and label signaling are done 191 concurrently using BGP. Whereas, with VPWS based on [RFC4448], label 192 signaling is done via LDP and service endpoint discovery is either 193 through manual provisioning or through BGP. In VPWS, redundancy is 194 limited to Active/Standby mode, while with E-VPN both Active/Active 195 and Active/Standby redundancy modes can be supported. In VPWS, backup 196 PWs are not used to carry traffic, while E-VPN traffic can be load- 197 balanced among primary and secondary PEs. On link or node failure, E- 198 VPN can trigger failover with the withdrawal of a single BGP route 199 per service, whereas with VPWS PW redundancy, the failover sequence 200 requires exchange of two control plane messages: one message to 201 deactivate the group of primary PWs and a second message to activate 202 the group of backup PWs associated with the access link. Finally, E- 203 VPN may employ data plane local repair mechanisms not available in 204 VPWS. 206 5 VPWS with multiple sites 208 The future revision of this draft will describe how a VPWS among 209 multiple sites (full mesh of P2P connections - one per pair of sites) 210 can be setup automatically without any explicit provisioning of P2P 211 connections among the sites. 213 6 Security Considerations 215 This document does not introduce any additional security constraints. 216 7 IANA Considerations 218 TBD 220 8 References 222 8.1 Normative References 224 [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate 225 Requirement Levels", BCP 14, RFC 2119, March 1997. 227 8.2 Informative References 229 [EVPN-REQ] A. Sajassi, R. Aggarwal et. al., "Requirements for 230 Ethernet VPN", draft-ietf-l2vpn-evpn-req-00.txt. 232 [EVPN] A. Sajassi, R. Aggarwal et. al., "BGP MPLS Based Ethernet 233 VPN", draft-ietf-l2vpn-evpn-00.txt. 235 Authors' Addresses 237 Sami Boutros 238 Cisco 239 170 West Tasman Drive 240 San Jose, CA 95134, US 241 Email: sboutros@cisco.com 243 Ali Sajassi 244 Cisco 245 170 West Tasman Drive 246 San Jose, CA 95134, US 247 Email: sajassi@cisco.com 249 Samer Salam 250 Cisco 251 595 Burrard Street, Suite 2123 252 Vancouver, BC V7X 1J1, Canada 253 Email: ssalam@cisco.com