Network Working Group X. Song Internet-Draft S. Wu Intended status: Informational H. Shao Expires: April 30, 2009 ZTE Corporation October 27, 2008 VPLS protection switching with ring access draft-song-l2vpn-vpls-ring-access-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 30, 2009. Abstract This document introduces a new method to access VPLS network using ring techonology . This method can improve VPLS access reliability. Fast switch can be done within 50 ms after link failure detection. It not only can be used in normal VPLS, but also can be used in VPLS PBB network. Song, et al. Expires April 30, 2009 [Page 1] Internet-Draft VPLS protect switching with ring access October 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. General Terminology . . . . . . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . 3 3. Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Dual-homing operation . . . . . . . . . . . . . . . . . . . . 5 4.1. Single CE ring access dual-homing operation . . . . . . . 5 4.2. Dual CE ring dual-homing operation . . . . . . . . . . . . 6 4.3. Multi CE ring multi-homing operation . . . . . . . . . . . 7 4.4. PE operation in the ring . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.1. Normative References . . . . . . . . . . . . . . . . . . . 9 8.2. Informative References . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Intellectual Property and Copyright Statements . . . . . . . . . . 10 Song, et al. Expires April 30, 2009 [Page 2] Internet-Draft VPLS protect switching with ring access October 2008 1. Introduction Virtual Private LAN Service (VPLS) is a Layer 2 Virtual Private Network (VPN) that gives its customers the appearance that their sites are connected via a Local Area Network (LAN). It is often required for a Service Provider (SP) to give the customer redundant connectivity to one or more sites, often called "multi-homing". Ring access to VPLS will be a good method to implement "multi-homing" technology .on one hand the access link will be protected more efficiently ,on the other hand ,ring is used very frequently in the current Ethernet network ,so deployment of the ring access to VPLS network is easy. Section 3 lays out some of the scenarios of ring access multi-homing. Section 4 describe how to implement the protect switch. Section 5 may someday discuss security considerations. 1.1. General Terminology Some general terminology is defined here; most is from [RFC4761] or [RFC4364]. Terminology specific to this memo is introduced as needed in later sections. A "Customer Edge" (CE) device, typically located on customer premises, connects to a "Provider Edge" (PE) device, which is owned and operated by the SP. A "Provider" (P) device is also owned and operated by the SP, but has no direct customer connections. A "VPLS Edge" (VE) device is a PE that offers VPLS services A VPLS domain represents a bridging domain per customer. A VPLS site is a grouping of ports on a PE that belong to the same VPLS domain. Sites are referred to as local or remote depending on whether they are configured on the PE router in context or on one of the remote PE routers (network peers). 2. 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 RFC-2119. 3. Scenarios The most basic scenario is shown in Figure 1. CE1 is a VPLS CE that is dual-homed to both PE1 and PE2 for redundant connectivity. Song, et al. Expires April 30, 2009 [Page 3] Internet-Draft VPLS protect switching with ring access October 2008 ............... . . ___ CE2 ___ PE1 . / / : PE3 __/ : Service : CE1 __ : Provider PE4 \ : . \___ CE3 \___ PE2 . . . ............... Figure 1: Scenario 1 Another extends of dual-homed VPLS module is shown in Figure 2. ............... . . ___ CE2 CE1 ----- PE1 . / | : PE3 | : Service : | : Provider PE4 | : . \___ CE3 CE2 ----- PE2 . . . ............... Figure 2: Scenario 2 In Figure 2, PE-CE-CE-PE forms a non-close ring. It is a typical ring access to VPLS, later the operation of ring will be described. ............... . . ___ CE2 CE1 ----- PE1 . / | : PE3 | : Service : Other User access point : Provider PE4 | : . \___ CE3 CE2 ----- PE2 . . . ............... Figure 3: Scenario 3 Song, et al. Expires April 30, 2009 [Page 4] Internet-Draft VPLS protect switching with ring access October 2008 ............... . . CE1 ----- PE1 . | : . CE4 | : / | : Service PE4 | : : CE2 ----- PE2 Provider : | : PE5 | : . \ | : . CE5 | : . CE3 ----- PE3 .............. Figure 4: Scenario 4 4. Dual-homing operation Before we start discussing ring access to VPLS network, some basic concept of ring technology must be represented. D1----D2-----D3----D4 From the Scenario above, D1-D4 is a simple non-close ring. When D1 and D4 access to one VPLS network, it seems that it is a close ring. One device of ring is selected to be master node. In normal operation, the master node must block one side link for all non- control Ethernet frames belonging to the given Domain, thereby avoiding a loop in the ring. If some link is detected failure, the master node will receive a link failure message, and then it unblocks the blocked link and allows Ethernet data frames to pass through that link. Later some Scenario of ring access to VPLS will be discussed. 4.1. Single CE ring access dual-homing operation Figure 1 shows a basic module of dual-homing VPLS system. PE1-CE1- PE2 can be regarded a simple ring. In the normal state, CE1 is a master node, CE1-PE1 is set in "forwarding" state and CE1-PE2 is in "blocking" state. And then traffic of CE1 only can flow to PE1, PE1 sends it to PE3. In the other direction, PE1 receives the traffic from PE3 and then sends to CE1.PE2 also maybe can receive the traffic from PE3, but because the CE-PE2 is blocked, so the traffic can not arrive CE1. Song, et al. Expires April 30, 2009 [Page 5] Internet-Draft VPLS protect switching with ring access October 2008 If PE1-CE1 link is detected failure (the method of detection is outside the scope of this document).CE1 will be notified the failure and set CE1-PE2 "forwarding" state. Supposed that the traffic is bidirectional, traffic of CE1 finds PE1- CE1 is link failure, so floods itself to PE2, and then PE2 sent it to PE3. In the process of PE2 and PE3, MAC will be updated. In the other direction, traffic will flow through the updated path PE3-PE2- CE1. Supposed that the traffic is unidirectional the traffic from CE1 to PE3 is the same as bidirectional. But the traffic from PE3 to CE1 can not switch to PE3-PE2-CE1 without MAC update of the other direction so the switch must rely on the PE MAC withdrawn massage. All above can make the traffic recover quickly when link failure. But there is a disadvantage . CE1 is the only access between user and VPLS network. If CE1 device is disabled, the traffic will be totally cut down. 4.2. Dual CE ring dual-homing operation Figure 2 is a module of dual CE dual-homing VPLS system. PE1-CE1- CE2-PE2 can be regarded a ring. This module can relax the disadvantage of single CE ring dual-homing module. Because there are many accesses between users and VPLS network, the network layout can split the user to different CE. In the normal state CE1 is selected a master node. CE1-PE1 is set in "forwarding" state, CE1-CE2 in "blocking" state, CE2-PE2 "forwarding" state. Then traffic of CE1 only can flow to PE1 . PE1 sends it to PE3. Traffic of CE2 only can flow to PE2.PE2 sends it to PE3. In the other direction, PE1 receives the traffic from PE3 and then sends it to CE1. PE2 also can receives the traffic from PE3 and sends it to CE2. If PE1-CE1 link is detected failure (the method of detection is outside the scope of this document), CE1 will be notified and then set CE1-CE2 in "forwarding" state. Supposed that the traffic is bidirectional, traffic of CE1 finds PE1- CE1 is link failure, so floods itself. Because CE1-CE2 is in "forwarding" state, CE2 can receive the traffic, then CE2 send it to PE2 and PE2 send it to PE3. In the process of PE2 and PE3, MAC will be updated. In the other direction, traffic will flow through the updated path PE3-PE2-CE2-CE1. Song, et al. Expires April 30, 2009 [Page 6] Internet-Draft VPLS protect switching with ring access October 2008 Supposed that the traffic is unidirectional, the traffic from CE1 to PE3 is the same as bidirectional. But the traffic from PE3 to CE1 can't switch to PE3-PE2-CE1 without MAC update of the other direction. So the switch must rely on the PE MAC withdrawn massage. Figure3 is also a module of dual CE ring dual-homing. In this module the access point between user and VPLS network are more. CE1 ----- PE1 | : C1 | C2 >< CE2 ----- PE2 Figure 5 In figure 5, PE1-CE1-C1-C2-CE2-PE2 is a ring. We set C2 is a master node. C2 will set one side link (C1-C2) in "forwarding" state and set the other side of link (C2-CE2) in "blocking " state. The user data of C2, C1, CE1 will arrive VPLS through PE1.The user data of CE2 will arrive VPLS network through PE2. If any link between PE1 and PE2 is detected failure, one message will sent to C2 (master node) and C2 will set C2-CE2 in "forwarding" state. Supposed that CE1-C1 is detected failure, C2 will open C2- CE2. The user data of C1, C2, CE2 will arrive VPLS network through PE2. The data of CE1 arrive VPLS network through PE1. It is shown in Figure 6. CE1 ----- PE1 >< C1 | C2 | CE2 ----- PE2 Figure 6 4.3. Multi CE ring multi-homing operation Figure 4 is a module of multi CE ring multi-homing VPLS system. PE1- CE1-CE2-PE2 can be regarded a ring. CE2-CE3-PE3 is another ring. The operation of PE1-CE1-CE2-PE2 ring is the same as dual CE ring Song, et al. Expires April 30, 2009 [Page 7] Internet-Draft VPLS protect switching with ring access October 2008 access dual-homing. In ring CE2-CE3-PE3, We set CE3 a master node of the ring. CE3-PE3 is in "forwarding" state and CE2-CE3 is in "blocking" state in normal operation. Once CE3-PE3 is detected failure, CE2-CE3 is set "forwarding". So the data of CE3 will sent to CE2 .CE2 send the traffic to VPLS network through PE2. 4.4. PE operation in the ring Chapter 4.1, 4.2, 4.3 describe that middle device of the ring do switching when some link is detected failure. This chapter will discuss edge of ring PE do some switching at the moment of link failure. In Figure 1, PE2 is the master node. At normal status, CE1-PE2 is set in "blocking" state. When CE1-PE1 link is detected failure, PE1 send a control message through PW to PE2, then PE2 set CE1-PE2 in "forwarding" state and send MAC flush message to PE1 and PE3. Traffic will flood and learn MAC over again. In figure 2, PE2 is also the master node. At normal status, CE2-PE2 is set in "blocking" state. So CE2 send traffic to CE1 and then CE1 send to PE1. When CE1-PE1 link is detected failure, PE1 sends one message to PE2, then PE2 sets CE2-PE2 in "forwarding" state and sends MAC flush message to PE1, PE3. Traffic will flood and then CE1 sent traffic to CE2, CE2 send it to PE2. 5. Security Considerations The security considerations in here are the same as the ones described in [RFC-4762], and there are no additional security aspects that need to be considered beyond the ones described in [RFC-4762]. 6. IANA Considerations There have been no IANA considerations so far in this document. 7. Acknowledgments The authors gratefully acknowledge the contributions of Wu Shaoyong, Shao Hong, Luo Jian. 8. References Song, et al. Expires April 30, 2009 [Page 8] Internet-Draft VPLS protect switching with ring access October 2008 8.1. Normative References [RFC4762] Lasserre, M. and V. Kompella, "Virtual Private LAN Service (VPLS) Using Label Distribution Protocol (LDP) Signaling", RFC 4762, January 2007. 8.2. Informative References [RFC4664] Andersson, L. and E. Rosen, "Framework for Layer 2 Virtual Private Networks (L2VPNs)", RFC 4664, September 2006. [RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, January 2007. Authors' Addresses Xiaojuan Song ZTE Corporation 68 zhijinghua Road Yuhuatai distinct,Nanjing 210000 P.R.China Email: song.xiaojuan@zte.com.cn Shaoyong Wu ZTE Corporation 68 zhijinghua Road Yuhuatai distinct,Nanjing 210000 P.R.China Email: wu.shaoyong@zte.com.cn Hong Shao ZTE Corporation 68 zhijinghua Road Yuhuatai distinct,Nanjing 210000 P.R.China Email: shao.hong@zte.com.cn Song, et al. Expires April 30, 2009 [Page 9] Internet-Draft VPLS protect switching with ring access October 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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