L2VPN Working Group                                  Pranjal Kumar Dutta 
                                                           Marc Lasserre 
Internet Draft                                            Alcatel-Lucent 
Intended status: Standard                                     
Expires: October 2009                                        Olen Stokes 
                                                        Extreme Networks 
                
                                                        April 26, 2009 
 
                                      
       LDP Extensions for Optimized MAC Address Withdrawal in H-VPLS 
                 draft-ietf-l2vpn-vpls-ldp-mac-opt-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 October 26, 2009. 

Abstract 

   [RFC4762] describes a mechanism to remove or unlearn MAC addresses  
   that have been dynamically learned in a VPLS Instance for faster  
   convergence on topology change. The procedure also removes the MAC    
   addresses in the VPLS that does not require relearning due to such  
   topology change. This document defines an extension to MAC Address  
   Withdrawal procedure with empty MAC List [RFC4762], which enables a  
   Provider Edge(PE) device to remove only the MAC addresses that needs 
   to be relearned.  

 
 
 
Dutta, et. al.         Expires October 26, 2009                [Page 1] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

     

Conventions used in this document 

   In examples, "C:" and "S:" indicate lines sent by the client and 
   server respectively. 

   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]. 

Table of Contents 

   1. Introduction...................................................3 
   2. Problem Description............................................4 
   3. Optimized MAC Flush Mechanism..................................6 
   4. PE-ID TLV......................................................7 
   5. Application of PE-ID TLV in Optimized MAC Flush...............10 
   5.1   PE-ID TLV Processing Rules.................................10 
   5.2 Optimized MAC Flush Procedures...............................11 
   6. General Applicability of PE-ID TLV............................13 
   7. Security Considerations.......................................13 
   8. IANA Considerations...........................................14 
   9. Acknowledgments...............................................14 
   10. References...................................................15 
      10.1. Normative References....................................15 
      10.2. Informative References..................................15 
   Author's Addresses...............................................16 
    
Terminology 
 
   This document uses the terminology defined in [RFC5036], [RFC4447]  
   and [RFC4762]. Throughout this document VPLS means the emulated  
   bridged LAN service offered to a customer. H-VPLS means the  
   hierarchical connectivity or layout of MTU-s and PE devices offering  
   the VPLS[RFC4762]. The terms spoke node and MTU-s in H-VPLS are used  
   interchangeably.  
 
 
 
 
                                                                         

                                              



 
 
Dutta, et. al          Expires October 26,2009                 [Page 2] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

1. Introduction 

   A method of Virtual Private LAN Service (VPLS), also known as 
   Transparent LAN Service (TLS) is described in [RFC4762]. A VPLS is 
   created using a collection of one or more point-to-point pseudowires 
   (PWs) [RFC4664] configured in a flat, full-mesh topology. The mesh 
   topology provides a LAN segment or broadcast domain that is fully 
   capable of learning and forwarding on Ethernet MAC addresses at the 
   PE devices.  
 
   This VPLS full mesh core configuration can be augmented with  
   additional non-meshed spoke nodes to provide a Hierarchical VPLS  
   (H-VPLS) service[RFC4762]. 
 
    MAC Address Withdrawal mechanism is described in [RFC4762] to  
   remove or unlearn MAC addresses for faster convergence on topology  
   change in dual-homed H-VPLS[RFC4762]. In dual-homed H-VPLS, an edge  
   device termed as MTU-s is connected to two PE devices via primary  
   spoke PW and backup spoke PW respectively. Such redundancy is  
   designed to protect against the failure of primary spoke PW or 
   primary PE device. When MTU-s switches over to backup PW, it is  
   required to flush the MAC addresses learned in the VPLS in upstream  
   PE devices participating in full mesh, to avoid black holing of    
   frames to those addresses. Note that forced switchover to backup PW  
   can be also performed at MTU-s administratively due to maintenance  
   activities on the primary spoke PW.  
 
   When backup PW is made active by MTU-s, it triggers LDP Address  
   Withdraw Message with list of MAC addresses to be flushed. The  
   message is forwarded over the LDP session(s) associated with the  
   newly activated PW. In order to minimize the impact on LDP 
   convergence time when MAC List TLV contains a large number of MAC  
   addresses, it may be preferable to send a LDP Address Withdraw  
   Message with an empty MAC List. Throughout this document the term  
   MAC Flush Message is used to specify LDP Address Withdraw Message  
   with empty MAC List described in [RFC4762] unless specified  
   otherwise.  
 
   As per the processing rules in [RFC4762] a PE device on receiving  
   a MAC flush message removes all MAC addresses associated with  
   the specified VPLS instance (as indicated in the FEC TLV) except the  
   MAC addresses learned over the newly activated PW. The PE device  
   further triggers MAC flush message to each remote PE device  
 
 
Dutta, et. al          Expires October 26,2009                 [Page 3] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

   connected to it in the VPLS full mesh. 
 
   This method of MAC flushing is modeled after Topology Change  
   Notification (TCN) in Rapid Spanning Tree Protocol (RSTP)[802.1w].  
   When a bridge switches from failed link to the backup link, the  
   bridge sends out a TCN message over the newly activated link. The  
   upstream bridge upon receiving this message flushes its entire MAC  
   addresses except the ones received over this link and sends the TCN  
   message out of its other ports in that spanning tree instance. The  
   message is further relayed along the spanning tree by the other  
   bridges. 
 
   When a PE device in the full-mesh of H-VPLS receives a MAC flush  
   message it also flushes the MAC addresses which are not affected  
   due to topology change, thus leading to unnecessary flooding and 
   relearning. This document describes the problem and a solution to 
   optimize the MAC flush procedure in [RFC4762] so that flush only  
   the set of MAC addresses that require relearning when topology 
   changes in H-VPLS.  
 
   [L2VPN-SIG] describes about inter-AS VPLS deployments models where  
   Multi-Segment PWs (MS-PW) may be used. The solution proposed in  
   this document is generic and is applicable to MS-PWs in H-VPLS. 
 
2.  Problem Description    

   Figure.1 describes a dual-homed H-VPLS scenerio for a VPLS instance  
   where the problem with the existing MAC flush method in [RFC4762] is  
   explained. 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
Dutta, et. al          Expires October 26,2009                 [Page 4] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

 
 
 
                                 PE-1                         PE-3 
                               +--------+                  +--------+            
                               |        |                  |        | 
                               |   --   |                  |   --   |  
   Customer Site 1             |  /  \  |------------------|  /  \  |->  
     CE-1               /------|  \ s/  |                  |  \S /  |  
       \     primary spoke PW  |   --   |           /------|   --   |  
        \             /        +--------+          /       +--------+  
         \    (MTU-s)/              |    \        /             | 
          +--------+/               |     \      /              | 
          |        |                |      \    /               |  
          |   --   |                |       \  /                | 
          |  /  \  |                |      H-VPLS Full Mesh Core| 
          |  \S /  |                |       / \                 | 
          |   --   |                |      /   \                |  
         /+--------+\               |     /     \               | 
        /     backup spoke PW       |    /       \              | 
       /              \        +--------+         \--------+--------+  
      CE-2             \       |        |                  |        |  
   Customer Site 2      \------|  --    |                  |  --    |  
                               | /  \   |------------------| /  \   |->  
                               | \s /   |                  | \S /   |  
                               |  --    |                  |  --    |  
                               +--------+                  +--------+           
                                 PE-2                         PE-4 
 
           Figure 1: Dual homed MTU-s in two tier hierarchy H-VPLS 
 
 
    In Figure.1, the MTU-s is dual-homed to PE-1 and PE-2. Only the  
   primary spoke PW is active at MTU-s, thus PE-1 acting as the primary  
   device to reach the full mesh in the VPLS instance. The MAC  
   addresses of nodes located at access sites (behind CE1 and CE2) are  
   learned at PE-1 over the primary spoke PW. PE-2, PE-3 and PE-4 learn  
   those MAC addresses on their respective mesh PWs terminating to  
   PE-1.  
 
   When MTU-s switches to backup spoke PW and activates it, PE-2     
 
 
Dutta, et. al          Expires October 26,2009                 [Page 5] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

   becomes the primary device to reach the full mesh core. Traffic  
   entering the H-VPLS from CE-1 and CE-2 is diverted by MTU-s to the  
   backup spoke PW. For faster convergence MTU-s may desire to unlearn  
   or remove the MAC addresses that have been learned in the upstream  
   VPLS full-mesh through PE-1. MTU-s may send MAC flush message to  
   PE-2 once the backup PW has been made active. As per the processing  
   rules defined in [RFC4762], PE-2 flushes the entire MAC addresses  
   learned in the VPLS from the PWs terminating at PE-1, PE-3 and PE-4  
   except the ones learned over the newly activated spoke PW. 
 
   In the H-VPLS core, PE devices are connected in full mesh unlike the  
   spanning tree connectivity in bridges. So the MAC addresses that  
   require flushing and relearning at PE-2 are only the MAC addresses  
   those have been learned on the PW connected to PE-1.  
 
   PE-2 further relays MAC flush messages to all other PE devices in  
   the full mesh. Same processing rule applies at all those PE devices.  
   For example, at PE-3 the entire MAC addresses learned from the PWs  
   connected to PE-1 and PE-4 are flushed and relearned subsequently.     
   As the number of PE devices in the full-mesh increases, the number  
   of unaffected MAC addresses flushed in a VPLS instance also  
   increases, thus leading to unnecessary flooding and relearning. With  
   large number of VPLS instances provisioned in the H-VPLS network  
   topology the amount of unnecessary flooding and relearning  
   increases. 
  
3. Optimized MAC Flush Mechanism     

   The basic principle of the optimized MAC flush mechanism is  
   explained with reference to Figure 1. On switching over to the     
   backup spoke PW when MTU-s triggers MAC flush message to PE-2, it  
   also communicates the unique PW endpoint identifier (PE-ID) in PE-1,  
   the formerly active PE device. In VPLS a PW terminates on a Virtual  
   Switching Instance (VSI) in a PE device. The PE-ID is relayed in all  
   the subsequent MAC flush messages triggered by PE-2 to its peer PE  
   devices in the full mesh. Each PE device that receives the message  
   identifies the VPLS (From FEC TLV) and its respective PW that  
   terminates in PE-1 (from PE-ID). Thus the PE device flushes only the  
   MAC addresses learned from that PW connected to PE-1.  
 


 
 
Dutta, et. al          Expires October 26,2009                 [Page 6] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

4. PE-ID TLV     

   This document defines a PW Endpoint Identifier (PE-ID) TLV for  
   LDP [RFC5036]. The PE-ID TLV carries the unique identifier of a  
   generic PW endpoint. 
 
   The encoding of PE-ID TLV follows standard LDP TLV encoding in  
   [RFC5036]. A PE-ID TLV contains a list of one or more PE-ID  
   Elements. Its encoding is: 
 
      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 

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+        
     |1|0|  PE-ID  TLV (0x0405)      |            Length             | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                        PE-ID Element 1                        |    
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                                                               | 
     ~                                                               ~ 
     |                                                               | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                        PE-ID Element n                        | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 

                     Figure 2. PE-ID TLV 

   U (Unknown) bit of thus LDP TLV MUST be set to 1. If the PE-ID TLV  
   is not understood then it is ignored the receiving device. 
 
   F (Forward) MUST be set to 0. Since the LDP mechanism used here is  
   targeted, the TLV is not forwarded if it is not understood by the  
   receiving device. 
 
   The Type field MUST be set to 0x405 (subject to IANA approval). This  
   identifies the TLV type as PE-ID TLV. 
 
   Length field specifies the total length in octets of the Value  
   in PE-ID TLV.  
 
   PE-ID Element 1 to PE-ID Element n: 
       There are several types of PE-ID Elements. The PE-ID Element  

 
 
Dutta, et. al          Expires October 26,2009                 [Page 7] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

       Encoding depends on the type of the PE-ID Element. A PE-ID  
       Element uniquely identifies a PW Endpoint. 
 
   A PE-ID Element value is encoded as 1 octet field that specifies the  
   element type, 1 octet field that identifies the length in octets of  
   the element value, and a variable length field that is type  
   dependent element value.  
 
   The PE-ID Element value encoding is: 
 
   PE-ID Element      Type              Length             Value 
   Type name 
 
   FEC-128 specific   0x01            2 octets           See below. 
   FEC-129 specific   0x02            Variable           See below.  
 
   The type of PE-ID Element depends on the type of FEC Element used to 
   provision the respective PW. 

   [RFC4447] defines two types of FEC elements that may be used for 
   provisioning PWs - Pwid FEC (type 128) and the Generalized ID (GID) 
   FEC (type 129).  

   The Pwid FEC element includes a fixed-length 32 bit value called the 
   PWid. The same PWid value must be configured on the local and remote 
   PE prior to PW setup.  

   The GID FEC element includes TLV fields for attachment individual 
   identifiers (AII) that, in conjunction with an attachment group 
   identifier (AGI), serve as PW endpoint identifiers. The endpoint 
   identifier on the local PE (denoted as <AGI, source AII or SAII>) is 
   called the source attachment identifier (SAI) and the endpoint 
   identifier on the remote PE (denoted as <AGI, target AII or TAII>) is 
   called the target attachment identifier (TAI). The SAI and TAI can be 
   distinct values. This is useful for provisioning models where the 
   local PE (with a particular SAI) does not know and must somehow learn 
   (e.g. via MP-BGP auto-discovery) of remote TAI values prior to 
   launching PW setup messages towards the remote PE.  

   FEC-128 specific PE-ID Element 
       This sub-type is to be used to identify a PW endpoint only if  
       Pwid FEC Element is used for signaling the PW. The encoding of  
       this PE-ID element is as follows:   
 
 
 
Dutta, et. al          Expires October 26,2009                 [Page 8] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

 
 
 
 
 
 
 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |     0x01      |    Length     |           PW type             | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     |                           PW ID                               | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
     |                      Endpoint Address                         | 
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 

                  Figure 3. FEC-128 specific PE-ID Element    
 
       PW type 
           The PW Type value from PWid FEC element. 
    
       PW ID 
           The PW ID value from the Pwid FEC element. 
 
       Endpoint Address 
           32-bit LSR-ID from the LDP-ID used in LDP signaling session  
           by a PW endpoint. 
 
 
   FEC-129 specific PE-ID element 
       This sub-type is to be used to indentify a PW endpoint only if  
       GID FEC Element is used for signaling the PW. The encoding of  
       this PE-ID element is as follows:   
     
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |     0x02      |    Length     |           PW type             | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |                           AGI TLV                             | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  
    |                           AII TLV                             | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   
 
             Figure 4. FEC-129 specific PE-ID Element  
 
 
Dutta, et. al          Expires October 26,2009                 [Page 9] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

  
       PW type 
           The PW Type value from GID FEC element. 
    
       PW ID 
           The PW ID value from the GID FEC element 
        
       AGI TLV 
           The AGI from the corresponding GID Element 
 
       AII TLV 
           The AII associated with the PW endpoint.  
 
 
5. Application of PE-ID TLV in Optimized MAC Flush    

   For optimized MAC flush, the PE-ID TLV MAY be sent as an OPTIONAL  
   parameter in existing LDP Address Withdraw Message with empty MAC  
   List. The PE-ID TLV carries the unique PW endpoint identifier in a  
   VPLS as described in section 4. 
 
   It is to note that for optimized MAC flush the PE-ID TLV carries  
   sufficient information for identifying the VPLS instance and the  
   unique VSI Identifier. For backward compatibility with MAC flush  
   procedures in [RFC4762] both FEC TLV and PE-ID TLV should be sent in  
   the MAC flush message. However the inclusion of the FEC-TLV should be  
   based on what would be the desired effect should the PE-ID not be  
   understood by the receiver.  In cases where the desired action when  
   the PE-ID is not understood would be to behave as described in  
   [RFC4762], then the FEC TLV SHOULD be included.  In cases where the  
   desired action when the PE-ID is not understood is to take no  
   action, then the FEC TLV SHOULD NOT be included. The PE-ID TLV  
   SHOULD carry the unique VSI identifier in the VPLS instance  
   (specified in the FEC TLV). The PE-ID TLV SHOULD be placed after the  
   existing TLVs in MAC Flush message in [RFC4762]. 
    
5.1 PE-ID TLV Processing Rules   

   This section describes the processing rules of PE-ID TLV that SHOULD  
   be followed in the context of MAC flush procedures in an H-VPLS.  
 

 
 
Dutta, et. al          Expires October 26,2009                [Page 10] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

   When an MTU-s triggers MAC flush after activation of backup spoke  
   PW, it MAY send the PE-ID TLV that identifies VSI in the formerly  
   active PE device. There may be cases where a PE device in full mesh  
   initiates MAC flush torwards the core when it detects a spoke PW  
   failure. In such a case the PE-ID TLV in MAC flush message  
   MAY identify its own VSI in the VPLS instance. Irrespective of  
   whether it is the MTU-s or PE device that initiates the MAC flush, a  
   PE device receiving the PE-ID TLV SHOULD follow the same processing  
   rules as described in this section. 
 
   If MS-PW signaled with GID Element is used in VPLS then a MAC flush  
   message is processed only at the T-PE nodes. In this section, a PE  
   device signifies only T-PE in MS-PW case unless specified otherwise. 
   
   When a PE device receives a MAC flush with PE-ID TLV, it SHOULD  
   flush all the MAC addresses learned in the VPLS from the PW that 
   terminates in the remote VSI identified by the PE-ID element. 
 
   If a PE-ID element received in the MAC flush message identifies the  
   local VSI, it SHOULD flush the MAC addresses learned from its  
   local spoke PW(s) in the VPLS instance.  
 
   If a PE device receives a MAC flush with the PE-ID TLV option 
   And a valid MAC address list, it SHOULD ignore the option and deal  
   with MAC addresses explicitly as per [RFC4762].  
 
   If a PE device that doesn't support PE-ID TLV receives a MAC flush  
   message with this option, it MUST ignore the option and follow the  
   processing rules as per [RFC4762].  
  
5.2 Optimized MAC Flush Procedures  

   This section explains the optimized MAC flush procedure in the  
   scenario in Figure.1.  
 
   When the backup PW is activated by MTU-s, it may send MAC flush  
   message to PE-2 with the optional PE-ID TLV. The PE-ID element  
   carries the VSI identifier in PE-1 for the VPLS. Upon receipt of the  
   MAC flush message, PE-2 identifies the VPLS instance that requires  
   MAC flush from the FEC element in the FEC TLV. From the PE-ID TLV,  
   PE-2 identifies the PW in the VPLS that terminates in PE-1. PE-2  

 
 
Dutta, et. al          Expires October 26,2009                [Page 11] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

   removes all MAC addresses learned from that PW.  
    
   PE-2 relays MAC flush messages with the received PE-ID to all its  
   peer PE devices. When the message is received at PE-3, it identifies  
   the PW that terminates in the remote VSI in PE-1. PE-3 removes all  
   MAC addresses learned on the PW that terminated in PE1.    
 
   There may be redundancy scenerios where a PE device in the full mesh  
   may be required to initiate optimized MAC Address Withdrawal.  
   Figure 5. shows a redundant H-VPLS topology to protect against  
   failure of MTU-s device. Provider RSTP may be used as selection  
   algorithm for active and backup PWs in order to maintain the  
   connectivity between MTU devices and PE devices at the edge. It is  
   assumed that PE devices can detect failure on PWs in either 
   direction through OAM mechanisms such as VCCV procedures for  
   instance.  
 
 
               MTU-1================PE-1===============PE-3 
                 ||                  || \             /||  
                 ||  Redundancy      ||  \           / || 
                 ||  Provider RSTP   ||   Full-Mesh .  ||         
                 ||                  ||  /           \ || 
                 ||                  || /             \|| 
               MTU-2----------------PE-2===============PE-4      
                      Backup PW 
 
               Figure 5. Redundancy with Provider RSTP 
         
   MTU-1, MTU-2, PE-1 and PE-2 participate in provider RSTP. By  
   configuration in RSTP it is ensured that the PW between MTU-1 and  
   PE-1 is active and the PW between MTU-2 and PE-2 is blocked (made  
   backup) at MTU-2 end. When the active PW failure is detected by  
   RSTP, it activates the PW between MTU-2 and PE-2. When PE-1 detects  
   the failing PW to MTU-1, it may trigger MAC flush into the full mesh  
   with PE-ID TLV that carries its own VSI identifier in the VPLS.  
   Other PE devices in the full mesh that receive the MAC flush  
   message identify their respective PWs terminating on PE-1 and  
   flush all the MAC addresses learned from it.  
 
   By default, MTU-2 should still trigger MAC flush as currently  
 
 
Dutta, et. al          Expires October 26,2009                [Page 12] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

   defined in [RFC4762] after the backup PW is made active by RSTP.  
   Mechanisms to prevent two copies of MAC withdraws to be sent in such  
   scenerios is out of scope of this document.  
 
   [RFC4762] describes multi-domain VPLS service where fully meshed  
   VPLS networks (domains) are connected together by a single spoke  
   PW per VPLS service between the VPLS "border" PE devices. To provide  
   redundancy against failure of the inter-domain spoke, full mesh of  
   inter-domain spokes can be setup between border PE devices and  
   provider RSTP may be used for selection of the active inter-domain  
   spoke. In case of inter-domain spoke PW failure, PE initiated MAC  
   withdrawal may be used for optimized MAC flushing within individual  
   domains. 
   

6. General Applicability of PE-ID TLV 

   This document defines the PE-ID TLV and its application in optimized  
   flushing of MAC addresses in H-VPLS on topology change. The use of  
   PE-ID TLV in MAC flush mechanism is OPTIONAL. 
 
   Different H-VPLS redundancy scenarios are possible. The use of the  
   PE-ID TLV applies to H-VPLS dual-homing scenarios described in this  
   document. The use of the PE-ID TLV in different scenarios is out of  
   scope. The protocols used in redundancy scenarios are outside the  
   scope. The document doesn't specify the device that should trigger  
   optimized MAC flush. The method to select the appropriate PE-ID in  
   various redundancy scenarios is out of scope.  
 
   There may be other L2VPN applications where PE-ID TLV may be  
   applicable and such applications are outside the scope of this  
   document.  
    

7. Security Considerations     

   - Control plane aspects    
      - LDP security (authentication) methods as described in [RFC5036]  
        is applicable here. Further this document implements security  
        considerations as in [RFC4447] and [RFC4762]. 
 
   - Data plane aspects 
 
 
Dutta, et. al          Expires October 26,2009                [Page 13] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

      - This specification does not have any impact on the VPLS 
        forwarding plane. 
    

8. IANA Considerations 

    The Type field in PE-ID TLV is defined as 0x405 and is subject to  
   IANA approval. 
  
9. Acknowledgments 

   The authors would like to thank the following people who have  
   provided valuable comments and feedback on the topics discussed in  
   this document: 
 
   Florin Balus 
   Prashanth Ishwar  
   Vipin Jain 
   John Rigby 
   Ali Sajassi 
    

   This document was prepared using 2-Word-v2.0.template.dot. 






















 
 
Dutta, et. al          Expires October 26,2009                [Page 14] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

10. References 

10.1. Normative References 

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

   [RFC4762]   Lasserre, M. and Kompella, V., "Virtual Private LAN  
               Services using LDP", RFC 4762, January 2007.  
 
   [RFC5036]   Andersson, L., et al. "LDP Specification",RFC5036,  
               October 2007.   
 

10.2. Informative References 

   [L2VPN-SIG]      Rosen, E., et al. .Provisioning, Autodiscovery, and  
                    Signaling in L2VPNs., work in progress. 
 
   [RFC4664]        Andersson, L., et al. "Framework for Layer 2  
                    Virtual Private Networks (L2VPNs)", RFC 4664,  
                    September 2006. 
  
   [RFC4447]        Martini. and et al., "Pseudowire Setup and 
                    Maintenance Using Label Distribution Protocol  
                    (LDP)", RFC 4447, April 2006. 
 
   [802.1w]         "IEEE Standard for Local and metropolitan area 
                    networks. Common specifications Part 3: Media  
                    Access Control (MAC) Bridges. Amendment 2: Rapid  
                    Reconfiguration", IEEE Std 802.1w-2001.  
 
    

    

    

    

    



 
 
Dutta, et. al          Expires October 26,2009                [Page 15] 

Internet-Draft    Optimized MAC Withdrawal in H-VPLS   April 26, 2009 
    

Author's Addresses 

   Pranjal Kumar Dutta 
   Alcatel-Lucent 
   701 E Middlefield Road, 
   Mountain View, CA 94043 
   USA 
    
   Email: pdutta@alcatel-lucent.com 
    

   Marc Lasserre 
   Alcatel-Lucent 
       
   Email: marc.lasserre@alcatel-lucent.com 
    

   Olen Stokes 
   Extreme Networks 
   PO Box 14129 
   RTP, NC  27709 
   USA 
   Email: ostokes@extremenetworks.com 
 

Copyright Notice 

   Copyright (c) 2009 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 in effect on the date of 
   publication of this document (http://trustee.ietf.org/license-info). 
   Please review these documents carefully, as they describe your rights 
   and restrictions with respect to this document. 

Acknowledgment 

   Funding for the RFC Editor function is currently provided by the 
   Internet Society. 

    




 
 
Dutta, et. al          Expires October 26,2009                [Page 16]