Network Working Group Siva Sivabalan (Ed.) Internet Draft Sami Boutros (Ed.) Intended status: Standards Track Luca Martini Expires: April 15, 2011 Cisco Systems, Inc. October 15, 2010 MAC Address Withdrawal over Static Pseudowire draft-boutros-pwe3-mpls-tp-mac-wd-00.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 15, 2011. Abstract This document specifies a mechanism to signal MAC address withdrawal notification using PW Associated Channel (ACH). Such notification is useful when statically provisioned PWs are deployed in VPLS/H-VPLS environment. This document is a product of a joint Internet Engineering Task Force(IETF) / International Telecommunication Union Boutros Expires April 15, 2011 [Page 1] Internet-Draft draft-boutros-pwe3-mpls-tp-mac-wd-00.txt October 2010 Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionalities of a packet transport network. Table of Contents 1. Introduction...................................................2 2. Terminology....................................................3 3. MAC Withdraw OAM Message.......................................3 4. Operation......................................................5 4.1.1. Operation of Sender..................................5 4.1.2. Operation of Receiver................................5 5. Security Considerations........................................5 6. IANA Considerations............................................5 7. References.....................................................6 7.1. Normative References......................................6 7.2. Informative References....................................6 Author's Addresses................................................7 Full Copyright Statement..........................................7 Intellectual Property Statement...................................8 1. Introduction An LDP-based MAC Address Withdrawal Mechanism is specified in RFC4762 [2] to remove dynamically learned MAC addresses when the source of those addresses can no longer forward traffic. This is accomplished by sending an LDP Address Withdraw Message with a MAC List TLV containing the MAC addressed to be removed to all other PEs over LDP sessions. When the number of MAC addresses to be removed is large, empty MAC List TLV may be used. [3] describes an optimized MAC withdrawal mechanism which can be used to remove only the set of MAC addresses that need to be re-learned in H-VPLS networks. The solution also provides optimized MAC Withdrawal operations in PBB-VPLS networks. A PW can be signaled via LDP or can be statically provisioned. In the case of static PW, LDP based MAC withdrawal mechanism cannot be used. This is analogous to the problem and solution described in [4] where PW OAM message has been introduced to carry PW status TLV using in- band PW Associated Channel. In this document, we propose to use PW OAM message to withdraw MAC address(es) learned via static PW. Boutros Expires April 15, 2011 [Page 2] Internet-Draft draft-boutros-pwe3-mpls-tp-mac-wd-00.txt October 2010 This document is a product of a joint Internet Engineering Task Force (IETF) / International Telecommunication Union Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionalities of a packet transport network. 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 [1]. 2. Terminology ACK: Acknowledgement. LDP: Label Distribution Protocol. MAC: Media Access Control MPLS: Multi Protocol Label Switching. OAM: MPLS Operations, Administration and Maintenance. PE: Provide Edge Node. PW: PseudoWire. TLV: Type, Length, and Value. VPLS: Virtual Private LAN Services. 3. MAC Withdraw OAM Message LDP provides a reliable packet transport for control plackets for dynamic PWs. This can be contrasted with static PWs which rely on re- transmission and acknowledgments (ACK) for reliable OAM packet delivery as described in [4]. The proposed solution for MAC withdrawal over static PW also relies on re-transmissions and ACKs. However, ACK is mandatory. A given MAC withdrawal notification is sent as a PW OAM message, and the sender keeps re-transmitting the message until it receives an ACK for that message. Once a receiver successfully remove MAC address(es) in response to a MAC address withdraw OAM message, it should not unnecessarily remove MAC address(es) upon getting refresh message(s). To facilitate this, the Boutros Expires April 15, 2011 [Page 3] Internet-Draft draft-boutros-pwe3-mpls-tp-mac-wd-00.txt October 2010 proposed mechanism uses sequence number, and defines a new TLV to carry the sequence number. The format of the MAC address withdraw OAM message is shown in Figure 1. The PW OAM message header is exactly the same as what is defined in [4]. Since the MAC withdrawal PW OAM message is not refreshed for ever, the "Refresh Timer" field in the message header is not used. A MAC address withdraw OAM message MUST contain a "Sequence Number TLV" otherwise the entire message is dropped. It may contain PE-ID or MAC Flush Parameter TLVs defined in [3] when static PWs are deployed in H-VPLS and PBB-VPLS scenarios. The sequence number TLV has U (Unknown) and F (Forward) bits set to 1 and 0 respectively so that if a receiver does not recognize the TLV, it drops the whole message. In this section, MAC List TLV, PE-ID TLV, and MAC Flush Parameter TLV are collectively referred to as "MAC TLV(s)". The processing rules of MAC List TLV is governed by [2], and the corresponding rules of PE-ID TLV and MAC Flush Parameter TLV are governed by [3]. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 1|Version| Reserved | 0xZZ PW OAM Message | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ACH TLV Header | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Refresh Timer | TLV Length |A| Flags | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U|F| Sequence Number TLV (TBD) | TLV Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | MAC List TLV | ~ PE-ID TLV (optional) ~ | MAC Flush Parameter TLV (optional) | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: MAC Address Withdraw PW OAM Packet Format. An ACK for MAC withdraw OAM message is the same as the one shown in Figure 1 except that: . A-bit is set. . It does not include MAC TLV(s). Boutros Expires April 15, 2011 [Page 4] Internet-Draft draft-boutros-pwe3-mpls-tp-mac-wd-00.txt October 2010 . It must include the Sequence Number TLV. 4. Operation This section describes how the initial MAC withdraw OAM messages are sent and retransmitted, as well as how the messages are processed and retransmitted messages are identified. 4.1.1. Operation of Sender Each PW is associated with a counter to keep track of the sequence number of the transmitted MAC withdrawal messages. Whenever a node sends a new set of MAC TLVs, it increments the transmitted sequence number counter, and include the new sequence number in the message. The sender expects an ACK from the receiver within a time interval which we call "Retransmit Time" which can be either a default or configured value. If the ACK arrives within the Retransmit Time, the sender assumes that the message transmission is successful. Otherwise, it retransmits the message with the same sequence number as the original message. 4.1.2. Operation of Receiver Each PW is associated with a counter to keep track of the sequence number of the MAC withdrawal message received last. Whenever a MAC withdrawal message is received, and if the sequence number on the message is greater than the receive counter, the MAC address(es) contained in the MAC TLV(s) is/are removed, and the receive counter is incremented. The receiver sends an ACK whose sequence number is the same as the received message. If the sequence number in the received message is smaller than or equal to the receive counter, the MAC TLV(s) is/are not processed. However, an ACK whose sequence number is the same as the received message is sent. 5. Security Considerations This document does not introduce any additional security constraints. 6. IANA Considerations IANA needs to assign the type value for Sequence Number TLV. Boutros Expires April 15, 2011 [Page 5] Internet-Draft draft-boutros-pwe3-mpls-tp-mac-wd-00.txt October 2010 7. References 7.1. Normative References [1] Bradner. S, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March, 1997. 7.2. Informative References [2] Mark Lassere, et. al, "Virtual Private LAN Service (LAN) Using Label Distribution Protocol (LDP) Signaling", RFC4762, January 2007. [3] Pranjal Kumar Dutta, et. al, "LDP Extensions for Optimized MAC Address Withdrawal in H-VPLS", draft-ietf-l2vpn-vpls-ldp-mac- opt-02.txt (work in progress), July 2010. [4] Luca Martini, et. al, "Pseudowire Status for Static Pseudowires", draft-ietf-pwe3-static-pw-status-00.txt (work in progress), February 2010. Boutros Expires April 15, 2011 [Page 6] Internet-Draft draft-boutros-pwe3-mpls-tp-mac-wd-00.txt October 2010 Author's Addresses Siva Sivabalan Cisco Systems, Inc. 2000 Innovation Drive Kanata, Ontario, K2K 3E8 Canada Email: msiva@cisco.com Sami Boutros Cisco Systems, Inc. 3750 Cisco Way San Jose, California 95134 USA Email: sboutros@cisco.com Luca Martini Cisco Systems, Inc. 9155 East Nichols Avenue, Suite 400 Englewood, CO, 80112 United States Email: lmartini@cisco.com Full Copyright Statement 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. 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