MPLS and Ethernet OAM Interworking
draft-ietf-pwe3-mpls-eth-oam-iwk-05

amp; Ethernet OAM Interworking        April 2012 
         

        - If PE1 is configured with a down MEP associated with the local 
        AC and CCM transmission is enabled, and the MEP associated with 
        the AC is configured to not support Interface Status TLV in CCM 
        messages, the MEP associated with the AC must resume 
        transmitting  CCM frames to the peer MEP in the client domain 
        (e.g., on CE1). 
         
        - If PE1 is configured to run E-LMI [MEF16] with CE1 and E-LMI 
        is used for fault notification, PE1 must transmit E-LMI 
        asynchronous STATUS message with report type Single EVC 
        Asynchronous Status indicating that PW is Active. 
         
        Further, if the PW receive defect was explicitly detected by 
        PE1, it must now notify PE2 about clearing of Receive Defect 
        state by clearing reverse defect notification. For PWs over 
        MPLS PSN or MPLS-IP PSN, this is either done via PW Status 
        message indicating working; or via VCCV-BFD diagnostic code if 
        VCCV CV type of 0x08/0x20 had been negotiated. When Native 
        Service OAM mechanism is supported on PE, it can also clear the 
        NS OAM notification specified in Section 3.1. 
         
        If PW receive defect was established via notification from PE2 
        or via loss of control adjacency, no additional action is  
        needed, since PE2 is expected to be aware of the defect 
        clearing. 
         
     5.3. PW Transmit Defect Entry Procedures 

        When the PW status transitions from working to PW Transmit 
        Defect state, PE1's ability to transmit user traffic to CE2 is 
        impacted. As a result, PE1 needs to notify CE1 about this 
        problem which has been detected by PE1. 
      
        Upon entry to the PW Transmit Defect state, the following must 
        be done: 
         
        - If PE1 is configured with a down MEP associated with the local 
        AC and CCM transmission is enabled, the MEP associated with the 
        AC MUST set the RDI bit in transmitted CCM frames or send status 
        TLV with interface down to the peer MEP in the client domain 
        (e.g. on CE1). 
         

      
      
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        - If PE1 is configured to run E-LMI [MEF16] with CE1 and E-LMI  
        is used for fault notification, PE1 must transmit E-LMI  
        asynchronous STATUS message with report type Single EVC  
        Asynchronous Status indicating that PW is Not Active. 
      
     5.4. PW Transmit Defect Exit Procedures 

        When the PW status transitions from PW Transmit Defect state to 
        working, PE1's ability to transmit user traffic to CE2 is 
        restored. As a result, PE1 needs to cease defect notifications 
        to CE1 and perform the following: 
         
        - If PE1 is configured with a down MEP associated with the local 
        AC and CCM transmission is enabled, the MEP associated with the 
        AC must clear the RDI bit in the transmitted CCM frames to the 
        peer MEP (e.g., on CE1). 
         
        - If PE1 is configured to run E-LMI [MEF16] with CE1, PE1 must 
        transmit E-LMI asynchronous STATUS message with report type 
        Single EVC Asynchronous Status indicating that PW is Active. 
      

     5.5. AC Receive Defect Entry Procedures 

        When AC status transitions from working to AC Receive Defect 
        state, PE1's ability to receive user traffic from CE1 is 
        impacted. As a result, PE1 needs to notify PE2 and CE1 about 
        this problem. 
         
        If the AC receive defect is detected by PE1, it must notify PE2 
        in the form of a forward defect notification. 
         
        When NS OAM is not supported on PE1, and for PW over MPLS PSN  
        or MPLS-IP PSN, forward defect notification is done via either 
        PW Status message indicating a forward defect or via VCCV-BFD 
        diagnostic code of forward defect if VCCV CV type of 0x08/0x20 
        had been negotiated. 
         
        When Native Service OAM mechanism is supported on PE1, it can 
        also use the NS OAM notification as specified in Section 3.1. 
         
        In addition to above actions, PE1 must perform the following: 
      
      
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        - If PE1 is configured with a down MEP associated with the local 
        AC and CCM transmission is enabled, the MEP associated with the 
        AC must set the RDI bit in transmitted CCM frames.  
         
         
        5.6. AC Receive Defect Exit Procedures 

        When AC status transitions from AC Receive Defect to working, 
        PE1's ability to receive user traffic from CE1 is restored. As 
        a result, PE1 needs to cease defect notifications to PE2 and CE1 
        and perform the following: 
         
        - When NS OAM is not supported on PE1 and for PW over MPLS PSN  
        or MPLS-IP PSN, forward defect notification is cleared via PW  
        Status message indicating a working state; or via VCCV-BFD 
        diagnostic code if VCCV CV type of 0x08 or 0x20 had been 
        negotiated. 
         
        - When Native Service OAM mechanism is supported on PE1, PE1 
        clears the NS OAM notification as specified in Section 3.1. 
         
        - If PE1 is configured with a down MEP associated with the local 
        AC and CCM transmission is enabled, the MEP associated with the 
        AC must clear the RDI bit in transmitted CCM frames to the 
        peer MEP in the client domain (e.g., on CE1).  
            

     5.7. AC Transmit Defect Entry Procedures 

        When AC status transitions from working to AC Transmit Defect, 
        PE1's ability to transmit user traffic to CE1 is impacted. As a 
        result, PE1 needs to notify PE2 about this problem. 
         
        If the AC transmit defect is detected by PE1, it must notify PE2 
        in the form of a reverse defect notification. 
      
        When NS OAM is not supported on PE1, in PW over MPLS PSN or 
        MPLS-IP PSN, reverse defect notification is either done via PW  
        Status message indicating a reverse defect; or via VCCV-BFD  
        diagnostic code of reverse defect if VCCV CV type of 0x08 or   
        0x20 had been negotiated. 
         
      
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        When Native Service OAM mechanism is supported on PE1, it can 
        also use the NS OAM notification as specified in Section 3.1. 
         
     5.8. AC Transmit Defect Exit Procedures 

        When AC status transitions from AC Transmit defect to working, 
        PE1's ability to transmit user traffic to CE1 is restored. As a 
        result, PE1 must clear reverse defect notification to PE2. 
         
        When NS OAM is not supported on PE1 and for PW over MPLS PSN or 
        MPLS-IP PSN, reverse defect notification is cleared via either a 
        PW Status message indicating a working state or via VCCV-BFD 
        diagnostic code if VCCV CV type of 0x08 had been negotiated. 
         
        When Native Service OAM mechanism is supported on PE1, PE1 can 
        clear NS OAM notification as specified in Section 3.1. 
         
     6. Acknowledgments 

        The authors are thankful to Samer Salam for his valuable 
        comments. 
      
7. Security Considerations 

        This document does not impose any security concerns since it 
        makes use of existing OAM mechanisms and mapping of these 
        messages does not change inherent security features. 
         
8. IANA Considerations 

        This document has no actions for IANA. 
      
     9. References 

     9.1. Normative References 

        [Y.1731] "OAM Functions and mechanisms for Ethernet based 
        networks", ITU-T Y.1731, May 2006 
         
        [802.1ag] "Connectivity Fault Management", IEEE 802.1ag/D8.1, 
        July 2007 
         

      
      
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        [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.

       [RFC4447] "Pseudowire Setup and Maintenance using LDP", RFC4447, 
        April 2006 
         
        [RFC5885] "Bidirectional Forwarding Detection (BFD) for the 
        Pseudowire Virtual Circuit Connectivity Verification (VCCV)",  
        RFC5885, June 2010 
         
        [802.3] "CDMA/CD access method and physical layer 
        specifications", Clause 57 for Operations, Administration and 
        Maintenance, 2005 
         
        [MEF16] "Ethernet Local Management Interface", MEF16, January 
                  2006  

     9.2. Informative References 

        [RFC3985] "Pseudo Wire Emulation Edge-to-Edge (PWE3) 
        Architecture", RFC 3985, April 2005 
         
        [RFC6310] "Pseudo Wire (PW) OAM Message Mapping", draft-ietf- 
        pwe3-oam-msg-map-14.txt, Work in progress, October 2010 
         
        [RFC5659] "An Architecture for Multi-Segment Pseudo Wire 
        Emulation Edge-to-Edge", RFC5659, October 2009 
         
     10. Appendix A: Ethernet Native Service Management 

        
        Ethernet OAM mechanisms are broadly classified into two 
        categories:  Fault Management (FM) and Performance Monitoring 
        (PM). ITU-T Y.1731 provides coverage for both FM and PM while 
        IEEE 802.1ag provides coverage for a sub-set of FM functions. 
      
        Ethernet OAM also introduces the concept of Maintenance Entity 
        (ME) which is used to identify the entity that needs to be   
        managed. An ME is inherently a point-to-point association. 
        However, in case of a multipoint association, Maintenance Entity 
        Group (MEG) consisting of different MEs is used. IEEE 802.1 uses 
        the concept of Maintenance Association (MA) which is used to 
        identify both point-to-point and multipoint associations. Each 
        MA consists of Maintenance End Points (MEPs) which are 
        responsible for originating OAM frames. In between the MEPs,  

      
      
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        there can also be Maintenance Intermediate Points (MIPs) which 
        do not originate OAM frames however do respond to OAM frames 
        from MEPs. 
      
        Ethernet OAM allows for hierarchical maintenance entities to 
        allow for simultaneous end-to-end and segment monitoring. This 
        is achieved by having a provision of up to 8 Maintenance Domain 
        Levels (MD Levels) where each MEP or MIP is associated with a 
        specific MD Level. 
        
       It is important to note that the common set of FM mechanisms 
       between IEEE 802.1ag and ITU-T Y.1731 are completely compatible. 
        
       The common FM mechanisms include: 
        
       1) Continuity Check Messages (CCM) 
       2) Loopback Message (LBM) and Loopback Reply (LBR) 
       3) Linktrace Message (LTM) and Linktrace Reply (LTR) 
      
     CCM messages are used for fault detection including misconnections 
     and mis-configurations. Typically CCM messages are sent as 
     multicast frames or Unicast frames and also allow RDI 
     notifications. LBM/LBR are used to perform fault verification,  
     while also allow for MTU verification and CIR/EIR measurements. 
     LTM/LTR can be used for discovering the path traversed between a 
     MEP and another target MIP/MEP in the same MA. LTM/LTR also allow 
     for fault localization. 
      
     In addition, ITU-T Y.1731 also specifies the following FM 
     functions: 
       4) Alarm Indication Signal (AIS) 
           
     AIS allows for fault notification to downstream and upstream nodes 
        
     Further, ITU-T Y.1731 also specifies the following PM functions: 
      
       5) Loss Measurement Message (LMM) and Reply (LMR) 
       6) Delay Measurement Message (DMR) and Reply (DMR) 
       7) 1-way Delay Message (1DM) 
      
     While LMM/LMR is used to measure Frame Loss Ratio (FLR), DMM/DMR is 
     used to measure single-ended (aka two-way) Frame Delay (FD) and 
     Frame Delay Variation (FDV, also known as Jitter). 1DM can be used 
      
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     for dual-ended (aka one-way) FD and FDV measurements. 
      
     Authors' Addresses: 

        Dinesh Mohan 
        Nortel 
        3500 Carling Ave 
        Ottawa, ON K2H8E9 
        Email: dinmohan@hotmail.com 
         
        Nabil Bitar 
        Verizon 
        60 Sylvan Road 
        Waltham, MA 02145 
        Email: nabil.n.bitar@verizon.com 
         
        Simon Delord 
        Telstra   
        242 Exhibition St   
        Melbourne VIC 3000, Australia   
        E-mail: simon.a.delord@team.telstra.com   
      
        Philippe Niger 
        France Telecom 
        2 av. Pierre Marzin 
         22300 LANNION, France 
         E-mail: philippe.niger@francetelecom.com 
       
        Ali Sajassi 
        Cisco 
        170 West Tasman Drive 
        San Jose, CA  95134, US 
        Email: sajassi@cisco.com 
         
        Ray Qiu 
        330 Central Expressway 
        Santa Clara, CA 95050, US 
        Email: ray@huawei.com 

      
      
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