Internet Engineering Task Force Luca Martini Internet Draft George Swallow Intended status: Standards Track Cisco Expires: April 25, 2011 October 25, 2010 MPLS LSP PW status refresh reduction for Static Pseudowires draft-martini-pwe3-status-aggregation-protocol-01.txt 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/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 25, 2010 Abstract This document describes a method includes generating an aggregated pseudowire status message on Multi-Protocol Label Switching (MPLS) network Label Switched Path (LSP). The method for transmitting the pseudowire (PW) status information is not new, however these protocol extension allows a Service Provider (SP) to reliably use the PW static status messages on individual PWs. The aggregated pseudowire status message configured to verify a current status of all pseudowires on the LSP. Martini & Swallow [Page 1] Internet Draftdraft-martini-pwe3-status-aggregation-protocol-01.txtctober 25, 2010 Table of Contents 1 Specification of Requirements ........................ 2 2 Introduction ......................................... 2 2.1 Terminology .......................................... 3 3 PW status refresh reduction protocol ................. 3 3.1 Protocol states ...................................... 4 3.1.1 INACTIVE ............................................. 4 3.1.2 STARTUP .............................................. 4 3.1.3 ACTIVE ............................................... 4 3.2 Timer value change transition procedure .............. 4 4 PW status refresh reduction Message .................. 5 4.1 PW status refresh reduction TLVs ..................... 6 4.1.1 MPLS-TP Tunnel ID .................................... 6 4.1.2 Static MPLS ID TLV ................................... 6 4.1.3 PW ID List ........................................... 7 5 PW status, and PW provisioning verification procedure ....7 6 PW status and PW status refresh procedure ........... 7 7 Security Considerations .............................. 7 8 IANA Considerations .................................. 7 9 References ........................................... 7 9.1 Normative References ................................. 7 9.2 Informative References ............................... 8 10 Author's Addresses ................................... 8 1. Specification of Requirements 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 [RFC2119]. 2. Introduction When PWs use an Multi Protocol Label Switched (MPLS) network as the Packet Switched Network (PSN), are setup according to [RFC4447] static configuration mode, the PW status information is propagated using the method described in [PW-STATUS]. There are 2 basic modes of operation described in [PW-STATUS] section 5.3: Periodic retransmission of non-zero status messages, and a simple acknowledge of PW status (sec 5.3.1 of [PW-STATUS]). The LSP level protocol described below applies to the case then Pw status is acknowledged Martini & Swallow [Page 2] Internet Draftdraft-martini-pwe3-status-aggregation-protocol-01.txtctober 25, 2010 immediately with a requested refresh value of zero. (no refresh) In this case the PW status refresh reduction protocol is necessary for several reasons , such as: -i. Greatly increase the scalability of the PW status protocol by reducing the amount of messages that a PE needs to periodically send to it's neighbors. -ii. Detect a remote PE restart. -iii. If the local state is lost for some reason, the PE needs to be able to request a status refresh from the remote PE -iv. Optionally detect a remote PE provisioning change. 2.1. Terminology FEC: Forwarding Equivalence Class LDP: Label Distribution Protocol LSP: Label Switching Path MS-PW: Multi-Segment Pseudowire PE: Provider Edge PW: Pseudowire SS-PW: Single-Segment Pseudowire S-PE: Switching Provider Edge Node of MS-PW T-PE: Terminating Provider Edge Node of MS-PW 3. PW status refresh reduction protocol PW status refresh reduction protocol consists of a simple message that is sent at the LSP level using the MPLS Generic Associated Channel. A PE using the PW status refresh reduction protocol MUST send the PW status refresh reduction Message as soon as a PW is configured on a particular LSP. The message is then re-transmitted at a locally configured interval indicated in the refresh timer field. If no acknowledgment is received, the protocol does not reach active state, and the PE SHOULD NOT send any PW status messages with a refresh timer of zero as described in [PW-STATUS] section 5.3.1. Martini & Swallow [Page 3] Internet Draftdraft-martini-pwe3-status-aggregation-protocol-01.txtctober 25, 2010 3.1. Protocol states The protocol can be in 3 possible states: INACTIVE, STARTUP, and ACTIVE. 3.1.1. INACTIVE This state is entered when the protocol is turned off. this state is entered if all PW on a specific LSP are unprovisioned, or the feature is unprovisioned. 3.1.2. STARTUP In this state the PE transmits periodic PW status refresh messages, with the Ack Session ID set to 0. The PE remains in this state until a PW status refresh message is received with the correct local session ID in the Ack Session ID Field. This state can be exited to the ACTIVE or INACTIVE state. 3.1.3. ACTIVE This state is entered once the PE receives a PW status refresh message with the correct local session ID in the Ack Session ID Field within 3.5 times the refresh timer field value of the last PW status refresh message transmitted. This state is immediately exited as follows: -i. A valid PW status refresh message is not received within 3.5 times the current refresh timer field value. (assuming a timer transition procedure is not in progress) New state: STARTUP -ii. A PW status refresh message is received with the wrong, or a zero value, Ack Session ID field value. New state: STARTUP -iii. All PWs using the particular LSP are unprovisioned, or the protocol is disabled. New state: INACTIVE 3.2. Timer value change transition procedure If a PE needs to change the refresh timer value field while the PW refresh reduction protocol is in the ACTIVE state, the following procedure must be followed: Martini & Swallow [Page 4] Internet Draftdraft-martini-pwe3-status-aggregation-protocol-01.txtctober 25, 2010 -i. A PW status refresh message is transmitted with the new timer value. -ii. If the new value is greater then the original one the PE will operate on the new timer value immediately. -iii. If the new value is smaller then the original one, the PE will operate according to the original timer value for a period 3.5 times the original timer value, or until the first valid PW status refresh message is received. A PE receiving a PW status refresh message with a new timer value, will immediately transmit an acknowledge PW status refresh message, and start operating according to the new timer value. 4. PW status refresh reduction Message The packet containing the refresh reduction message is constructed as follows: (omitting link layer information) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MPLS LSP (tunnel) Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | GAL | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 1|Version| Reserved | 0xZZ PW OAM Message | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Refresh Timer | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Total TLV Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Variable Length Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ PE Information TLVs ~ | Continued | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This message contains the following fields: * Session ID A non-zero, locally selected session number that is not preserved if the local PE restarts. Martini & Swallow [Page 5] Internet Draftdraft-martini-pwe3-status-aggregation-protocol-01.txtctober 25, 2010 * Ack Session ID The Session ID received from the remote PE. * Refresh Timer. A value, in seconds, that indicates the desired refresh interval. * Total TLV Length Total length in octets of the TLVs. A value of zero means no TLVs are following. * TLV Type The Type of the value that follows. Types are allocated in this document, and by IANA. * TLV Length Length of the value field of the TLV. A value of Zero means an empty TLV. * PE Information TLVs A set of one or more TLVs that contain information about the local PE. 4.1. PW status refresh reduction TLVs The PW status refresh reduction TLVs are informational TLVs, that allow the remote PE to verify certain provisioning information. 4.1.1. MPLS-TP Tunnel ID This TLV MUST always be present , and contains the address of the MPLS-TP tunnel ID. 4.1.2. Static MPLS ID TLV The PE address of the Local PE. Martini & Swallow [Page 6] Internet Draftdraft-martini-pwe3-status-aggregation-protocol-01.txtctober 25, 2010 4.1.3. PW ID List This OPTIONAL TLV contains a list of the provisioned PWs on the LSP. [ editor's note: extensive procedures TBD ] 5. PW status, and PW provisioning verification procedure TBD [ editor's note: usage, and procedures for the PW ID List TLV ] 6. PW status and PW status refresh procedure TBD [ editor's note: local PE behavior for PW status transmittal in ACTIVE/STARTUP/INACTIVE state] 7. Security Considerations TBD 8. IANA Considerations Setup a new registry , of PW status refresh reduction TLVs. ( to be specified in a future version ) 9. References 9.1. Normative References [RFC2119] Bradner. S, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March, 1997. [RFC4447] "Transport of Layer 2 Frames Over MPLS", Martini, L., et al., rfc4447 April 2006. [ON DEMAND] Bahadur et.al. "MPLS on-demand Connectivity Verification, Route Tracing and Adjacency Verification", draft-ietf-mpls-tp-on-demand-cv-01.txt, IETF Work in Progress, October 2010 [PW-STATUS] L. Martini, G. Swallow, G. Heron, M. Bocci "Pseudowire Status for Static Pseudowires", draft-ietf-pwe3-static-pw-status-01.txt, (work in progress), October 2010 Martini & Swallow [Page 7] Internet Draftdraft-martini-pwe3-status-aggregation-protocol-01.txtctober 25, 2010 9.2. Informative References [RFC5586] M. Bocci, Ed., M. Vigoureux, Ed., S. Bryant, Ed., "MPLS Generic Associated Channel", rfc5586, June 2009 10. Author's Addresses Luca Martini Cisco Systems, Inc. 9155 East Nichols Avenue, Suite 400 Englewood, CO, 80112 e-mail: lmartini@cisco.com George Swallow Cisco Systems, Inc. 300 Beaver Brook Road Boxborough, Massachusetts 01719 United States e-mail: swallow@cisco.com Copyright Notice Copyright (c) 2010 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. Expiration Date: April 2011 Martini & Swallow [Page 8]