Internet Draft David Allan Internet-draft: draft-allan-pw-o-pbt-03.txt Nigel Bragg Informational Hamid Ould-Brahim Nortel Jose Luis Pena Luis Perez Roldan Telefonica Himanshu Shah Ciena Nurit Sprecher Nokia Siemens Networks July 2007 Carrying PWE3 Pseudo Wires over Provider Backbone Transport (PBB-TE, 802.1Qay) 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 in April 2007. Copyright Notice Copyright (C) The Internet Trust (2007). Allan et.al December 2007 Page 1 Pseudo Wires over Provider Backbone Transport Abstract Provider Backbone Transport (PBT, known as well as PBB-TE and progressed in IEEE as 802.1Qay [802.1Qay]) provides a mechanism where native Ethernet point-to-point tunnels can be configured or signaled across a provider-based Ethernet network [FEDYK]. PWE3 architecture defines a mechanism, called pseudowires, that emulates the essential attributes of a layer-2 and layer-1 service over a Packet Switched Network (PSN). This draft describes the architecture and procedures where Pseudowires are carried across PBT tunnels. In this proposal PBT tunnels are used as the PSN. 1. Introduction Provider Backbone Transport (PBT, known as well as PBB-TE and progressed in IEEE as 802.1Qay) provides a mechanism where native Ethernet point-to-point tunnels can be configured or signaled across a provider-based Ethernet network [FEDYK]. PWE3 architecture defines a mechanism, called pseudowires, that emulates the essential attributes of a layer-2 and layer-1 service over a Packet Switched Network (PSN). This draft describes the architecture and procedures where Pseudowires are carried across PBT tunnels. In this proposal PBT tunnels are used as the PSN. 2. Acronyms B-MAC Backbone MAC B-VID Backbone VLAN ID B-VLAN Backbone Virtual LAN BEB Backbone Edge Bridge BCB Backbone Core Bridge C-MAC Customer MAC C-VID Customer VLAN ID C-VLAN Customer Virtual LAN DA Destination Address LLC Logical Link Control MAC Media Access Control PBB Provider Backbone Bridge PBB-TE Provider Backbone-Bridging Traffic Engineering PBT Provider Backbone Transport RTP Real time protocol SA Source Address VID VLAN ID VLAN Virtual LAN 3. Architecture Allan et.al. December 2007 Page 2 Pseudo Wires over Provider Backbone Transport Figure 1 illustrates the role of PBT in the PWE3 architecture [PW- ARCH]. Figure 2 describes the data-plane for PWoPBT. +---------------------+ +-------------------------+ | Payload |------------->| Raw payload if possible | /=====================\ +-------------------------+ H Payload Convergence H-----------+->| Flags, seq #, etc. | H---------------------H / +-------------------------+ H Timing H---------/--->| RTP | H---------------------H / +-------------+ | H Sequencing H----one of | | \=====================/ \ | +-----------+ | PW Demultiplexer |---------+--->| PW service label | +---------------------+ +-------------------------+ | PSN Convergence |------------->| Not needed | +---------------------+ +-------------------------+ | PSN |------------->| PBT Tunnel | +---------------------+ +-------------------------+ | Data-Link |------------->| Data-link | +---------------------+ +-------------------------+ | Physical |------------->| Physical | +---------------------+ +-------------------------+ Figure 1: PWE3 architecture illustrating role of PBT When the physical layer is Ethernet, the data-link and physical layers are effectively a single layer from the point of view of control and management. The PWoPBT architecture takes advantage of the fact that the Ethernet LLC permits multiple protocols to be simultaneously multiplexed over a PBT protection group. This permits both MPLS/PW payload/PDUs and IP control and OAM PDUs to be multiplexed together. +-ATM +-PING +-Ethernet +-BFD +-FR +-ETHOAM +-HDLC | +-PPP | +-SaTOP | | (etc.) | +----------+ +--------+ |PW payload| | PW OAM | +----------+ +--------+ | | 0000 0001 +--------------+ \ / | LDP | Allan et.al. December 2007 Page 3 Pseudo Wires over Provider Backbone Transport +-------------------+ +--------------+ | PW CW | | TCP | +-------------------+ +--------------+ +--------------+ | PW label | | IP | |802.1ag/Y.1731| +-------------------+ +--------------+ +--------------+ | | | =0x8847 =0x0800 =0x8902 \ | / /+-------------------------------------------------+\ / | etype | \ / +-------------------------------------------------+ \ / | VLAN | PBT 802.1Q+-------------------------------------------------+ PSN header| SA-MAC | / \ +-------------------------------------------------+ / \ | DA-MAC | / \+-------------------------------------------------+/ Figure 2: Multiplexing of PW bearer, PW OAM, PW control & tunnel OAM over PBT tunnel Further, control, Ethernet PW packets and OAM PDUs inherently share fate with the PBT tunnel or (where used) protection group simplifying the job of proactive monitoring of connectivity. Where a protection group is used control, OAM and bearer traffic is forwarded on the currently active path of the protection group. Frequently more than one diversely routed tunnel is set up to form a protection group, the most common instantiation being 1:1 protection switching. There may be multiple (even protected) tunnels between a pair of PEs and only one will be used for PW signaling. Note that out-of-band signaling can as well be used (such as through the IP route between the PEs Further the PW may directly inherit availability status from the tunnel or protection group. In addition to the regular IP Infrastructure that may be established to support PSN Control Plane (routing, GMPLS signaling) exchanges, a PBT tunnel may appear as a single IP hop away. The IP control channel allows the mode of operation to be directly analogous to channel associated signaling. PW labels offered over the signaling channel are directly bound to the PBT tunnel and inherit the QoS characteristics of the tunnel directly. A priority may be set to the control packets. 4. Signaling Procedures In the context of control plane for PW over PBT, RFC4447 can be used with no new extensions. Indeed, one targeted LDP hello adjacency will be established between any two PEs connected by at least one PBT tunnel or through an IP route. A PE implements only one Allan et.al. December 2007 Page 4 Pseudo Wires over Provider Backbone Transport transport IP address that is common to all PBT tunnel terminations. This is typically the PE loopback address. LDP extended discovery is used over the currently active path of the PBT protection group (or using the IP route). In a fault free network this will be the working path. The label space indicated in the LDP Link Hello message MUST be the per-platform label space. Label exchange procedures are as per [PW-CONTROL] for single segment pseudo wires and as per [MS-PW] for multi-segment pseudo wires. PBT tunnels/protection groups may interconnect two T-PEs, a T-PE to an S-PE, an S-PE to an S-PE/T-PE. PW control plane assumes an a- priori existence of a PBT protection group between a given pair of PEs. 4.1 Fault scenarios Failure of a single PBT tunnel in the protection group will not disrupt either the bearer path or the control adjacency. Failure of all tunnels in a protection group or the failure of a PE at a terminating end to a protection group will disrupt the service. If the network has not been completely severed by link failures, PBT may be able to recover connectivity prior to expiration of the LDP hold timer. 5. OAM Procedures 5.1 Capability Indication OAM capability indication procedures as per [VCCV] and extended in [MOHAN] are used unmodified. 5.2 Control Channel In-band VCCV may be used for both SS and MS PWs without modifications to procedures described in [VCCV] and [MS-PW]. 5.3 VCCV BFD For a single segment PW, use of VCCV BFD is not necessary as the PW is 1:1 congruent with the transporting PBT protection group (which does not implement load spreading such as ECMP) so the PBT OAM effectively instruments connectivity for the set of PWs carried. For MS-PWs where a least one segment transits a non PBT network such as ECMP/LDP, VCCV BFD may be used as PSN OAM since congruency with the PW layer cannot be guaranteed. Allan et.al. December 2007 Page 5 Pseudo Wires over Provider Backbone Transport 5.4 VCCV-PING Normally the return path for a VCCV-PING reply is the PW in the reverse direction. This is indicated by LSP-PING reply mode 2. It is also possible to indicate that the reply traverse each segment of a MS-PW by indicating a reply mode of 3 (use of router alert in the reply message) although this only slightly modifies the return path congruency for pure PBT architectures, and is of primary use in decoupling the return path from the PW in other PSN types. 5.5 VCCV-ETHOAM [MOHAN] proposes the use of [802.1ag] and [Y.1731] OAM PDUs in conjunction with the VCCV channel. In this scenario MEPs are co- located with the PW end points and for MS-PWs, MIPs are co-located with the S-PEs. 6. Others PBT tunnels introduce no new procedures into the multi-segment Pseudowire architecture (MS-PW). It simply takes the role of a PSN Tunnel in one or more segments. Bi-directional PBT tunnels are consistent with the requirement for both directions of an MS-PW to transit common S-PE devices. 7. Security Considerations The use of PBT as a PSN introduces no new security vulnerabilities to the PWE architecture. 8. References [FEDYK] GMPLS Control of Ethernet, IETF Internet Draft, draft- fedyk-gmpls-ethernet-pbt-01.txt, October 2006 [MOHAN] VCCV Extension for Ethernet OAM, IETF Internet Draft draft-mohan-pwe3-vccv-eth-01.txt, January 2007 [MS-PW] Dynamic Placement of Multi Segment Pseudo Wires, IETF Internet Draft, draft-ietf-pwe3-dynamic-ms-pw-02.txt, October 2006 [PW-ARCH] Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture, IETF RFC 3985, March 2005 [PW-CONTROL] Pseudowire Setup and Maintenance using the Label Distribution Protocol, IETF RFC 4447, April 2006 [RFC 3036] LDP Specification, IETF RFC 3036, January 2001 [VCCV] Pseudo Wire Virtual Circuit Connectivity Verification (VCCV), IETF Internet Draft, draft-ietf-pwe3-vccv- 12.txt, January 2007 Allan et.al. December 2007 Page 6 Pseudo Wires over Provider Backbone Transport [Y.1731] Y.1731 (2006), ITU-T Recommendation, OAM functions and mechanisms for Ethernet based networks [802.1ag] Connectivity Fault Management, IEEE 802.1ag draft 6.1, work in progress. [802.1Qay] Virtual Bridged Local Area Network, Provider Backbone Bridge Traffic Engineering, IEEE 802.1Qay, work in progress. 9. Author's Address Dave Allan Nortel Networks Phone: 1-613-763-6362 3500 Carling Ave. Email: dallan@nortel.com Ottawa, Ontario, CANADA Nigel Bragg Nortel Networks UK Limited Phone +44 (0) 1279 40 2052 London Road, Harlow, Essex, Email: nbragg@nortel.com CM17 9NA, UK Hamid Ould-Brahim Nortel Networks Phone: 1-613-765-3418 3500 Carling Ave. Email: hbrahim@nortel.com Ottawa, Ontario, CANADA Jose Luis Pena Telefonica I+D Phone: 34-91-337-4579 Emilio Vargas 6. Email: sedano@tid.es 28043 Madrid. SPAIN Luis Perez Roldan Telefonica I+D Phone: 34-91-337-4668 Emilio Vargas 6. Email: lperez@tid.es 28043 Madrid. SPAIN Himanshu Shah Phone: 978-489-2196 Ciena Email: hshah@ciena.com 35 Nagog Park, Acton, MA 01720 Nurit Sprecher Phone: +972 9 7751229 Nokia Siemens Networks, Email: nurit.sprecher@nsn.com GmbH & Co. KG Research, Technology and Platform Industry Environment, Carrier Ethernet and Transport 3 Hanagar St. Neve Ne'eman B 45241 Hod Hasharon, Israel Allan et.al. December 2007 Page 7 Pseudo Wires over Provider Backbone Transport 10. Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. 11. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 12. Full Copyright Statement Copyright (C) The IETF Trust (2007). 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. 13.Acknowledgments The authors would like to thank Dinesh Mohan for his contributions to this document. Allan et.al. December 2007 Page 8