One document matched: draft-mohan-sajassi-l2vpn-vpls-pm-00.txt



   Internet Draft Document                               Dinesh Mohan 
   Layer-2 VPN Working Group                          Nortel Networks 
   draft-mohan-sajassi-l2vpn-vpls-pm-00.txt               Ali Sajassi 
                                                        Cisco Systems 
                                                                      
                                                       Shahram Davari 
                                                           PMC Sierra 
                                                                      
                                                        Vasile Radoaca 
                                                       Nortel networks 
                                                                      
   Expires: November 2004                                  March 2004 
                                                                         
    
          Performance Management for Virtual Private LAN Services  
                 draft-mohan-sajassi-l2vpn-vpls-pm-00.txt 
    
   1.  Status of this Memo 
    
   This document is an Internet-Draft and is in full conformance 
   with all provisions of Section 10 of RFC2026. 
    
   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. 
    
   2.  Abstract 
    
    
   3.  Conventions 
    
   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 
    
   Placement of this Memo in Routing Area 
    
   RELATED DOCUMENTS 
    
    
    
     
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   http://www.ietf.org/internet-drafts/draft-ietf-l2vpn-vpls-
   requirements-00.txt 
   http://www.ietf.org/internet-drafts/draft-ietf-l2vpn-l2-framework-
   03.txt 
   http://www.ietf.org/internet-drafts/draft-ietf-l2vpn-vpls-ldp-01.txt 
    
    
   WHERE DOES THIS FIT IN THE PICTURE OF THE ROUTING WORK 
    
   L2VPN 
    
   WHY IS IT TARGETED AT THIS WG 
    
   This draft describes Performance Management mechanisms for VPLS 
   which is a Layer-2 VPN. 
    
   JUSTIFICATION 
    
   This draft describes Performance Management mechanisms for VPLS 
   which is a Layer-2 VPN. 
 
 
   Table of Contents 
    
   1. Status of this Memo.............................................1 
   2. Abstract........................................................1 
   3. Conventions.....................................................1 
   4. Overview........................................................3 
   5. Layering........................................................4 
   5.1. OAM Domains...................................................5 
   5.2. Maintenance & Intermediate Points.............................6 
   5.2.1. Maintenance and Intermediate Points IDs.....................8 
   6. Performance Parameters..........................................8 
   6.1. Frame Loss (FL)...............................................8 
   6.2. Frame Delay (FD)..............................................8 
   6.3. Frame Delay Variation (FDV)...................................8 
   6.4. Availability..................................................9 
   6.5. Other Parameters..............................................9 
   6.5.1. Errored Frame Seconds (FL)..................................9 
   6.5.2. Frame Throughput............................................9 
   6.5.3. Frame Tx....................................................9 
   6.5.4. Frame Rx....................................................9 
   6.5.5. Frame Drop.................................................10 
   7. Performance Measurement Mechanisms.............................10 
   7.1. Performance Management Collection Method.....................11 
   7.2. Frame Loss Measurement.......................................11 
   7.2.1. Unsolicited Method.........................................12 
    
     
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   7.2.2. Solicited Method...........................................12 
   7.3. Frame Delay Measurement......................................13 
   7.4. Frame Delay Variation Measurement............................13 
   7.5. Availability Measurement.....................................14 
   8. Acknowledgments................................................14 
   9. Security Considerations........................................14 
   10. Intellectual Property Considerations..........................14 
   11. Full Copyright Statement......................................14 
   12. References....................................................15 
   13. Authors' Addresses............................................15 
    
    
   4.  Overview 
    
   The Scope of network management functionality (aka OAM&P: Operation, 
   Administration, Maintenance, and Provisioning) for any network 
   technology is very broad in nature. 
    
   OSI has defined the following five generic functional areas for 
   network management, commonly abbreviated as ôFCAPSö [NM-Standards]: 
   Fault Management (FM), Performance Management (PM), Configuration 
   Management, Accounting Management, and Security Management. This 
   draft only deals with Performance Management aspects of OAM&P for 
   VPLS and defines mechanisms and procedures for it. Fault management 
   aspects of OAM&P for VPLS are addressed in a companion draft [FM-
   SAJASSI-MOHAN]. 
    
   Performance Management deals with mechanism(s) that allow 
   determining and measuring the performance of network/services under 
   consideration and notification of them. Performance Management can 
   be used to verify the compliance to both the service and network 
   level specifications. However, only the service-level aspects of the 
   performance management (corresponding to VPLS instances) are 
   addressed here. 
    
   Performance Management typically consists of measurement of 
   Performance Parameters e.g. Frame Loss, Frame Delay, Frame Delay 
   Variation aka Jitter etc. This draft focuses on the following 
   performance parameters and measurements: 
    
     - Frame Loss Measurement 
     - Delay Measurement 
     - Delay Variation Measurement 
     - Availability Measurement 
      
   Other performance parameters are briefly introduced in this draft 
   and are for FFS.  
    
    
     
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   This document provides a description and a reference model for OAM 
   layering and furthermore emphasizes the importance of proper 
   independent layering in design and development of OAM functionality. 
   Next it defines the performance parameters and specifies the 
   mechanisms and procedures for performance measurement for VPLS. 
    
   This proposal is aligned with the current discussions in other 
   standard bodies such as ITU-T Q3/13, IEEE 802.1, and MEF which are 
   addressing OAM for both Ethernet-based services and Ethernet-based 
   networks.  
 
 
   5.  Layering 
    
   As defined in [L2-FRWK], Virtual Private LAN Service is a bridged 
   LAN service provided to a set of CEs that are members of a VPN. The 
   CEs that are member of the same VPN (e.g., the same VPLS instance) 
   communicate with each other as if they are connected via a bridged 
   LAN. The bridged LAN functionality is emulated by a network of PEs 
   to which the CEs are connected. This network of PEs can belong to a 
   single network operator or can span across multiple network 
   operators. Furthermore, it can belong to a single service provider 
   or can span across multiple service providers. A service provider is 
   responsible for providing VPLS services to its customers; whereas, a 
   network operator (aka facility provider) provides the necessary 
   facilities to the service provider(s) in support of their services.  
   A network operator and a service provider can be the same entity or 
   they can be different administrative organizations.  
    
    
   When discussing the performance management mechanisms for VPLS, it 
   is important to consider that the end-to-end service can span across 
   different types of VPLS networks. As an example, in case of [VPLS-
   LDP], the access network on one side can be bridged network e.g. 
   [IEEE 802.1ad], as described in section 11 of [VPLS-LDP]; whereas, 
   the access network on other side can be MPLS based as described in 
   section 10 of [VPLS-LDP]; and the core network connecting them can 
   be IP, MPLS, ATM, or SONET. Similarly, the VPLS service instance can 
   span across distributed VPLS as described in [VPLS-ROSEN]. 
   Therefore, it is important that the performance management 
   mechanisms can be applied to all these network types. Each such 
   network may be associated with a separate administrative domain and 
   also multiple such networks may be associated with a single 
   administrative domain. Different types of pseudo wires may be in use 
   to support end-to-end VPLS. Therefore, for VPLS performance 
   management, it is important to ensure that the performance 
   management mechanisms for VPLS are independent of the underlying 
   transport mechanisms (e.g., 802.3, MPLS, IP, ATM, SONET, etc.) and 
   solely rely on Ethernet MAC layer.  
    
    
     
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   As shown in Figure 1, an example of VPLS service is shown across a 
   service provider network marked by UPE and NPE devices. The customer 
   A is represented by CE devices across its different sites. The 
   service provider network is segmented into core network and two 
   types of access network. Figure 1(A) shows the bridged access 
   network represented by its bridge components marked ôBö, and the 
   MPLS access and core network represented by MPLS components marked 
   ôPö. Figure 1(B) shows the service/network view at the Ethernet MAC 
   layer marked by ôEö. 
                                                         
           ---                                                   --- 
          /   \         ------      -------      ----           /   \ 
          | A CE--     /      \    /       \    /    \       --CE A | 
          \   /   \   /        \  /         \  /      \     /   \   / 
           ---     --UPE       NPE          NPE        UPE--     --- 
                      \        /  \         /  \      / 
                       \      /    \       /    \    /      
                        ------      -------      ---- 
    
       (A)    CE----UPE--B--B--NPE---P--P---NPE---P----UPE----CE 
    
       (B)    E------E---E--E---E------------E----------E-----E 
    
    
                        Figure 1 
    
   As shown in Figure 1(B), only the nodes with Ethernet functionality 
   are visible to Performance Management mechanisms operating at 
   Ethernet MAC layer and the P nodes are invisible. Therefore, the 
   Performance management along the path of P nodes (e.g., between two 
   PEs) is covered by transport layer and it is outside the scope of 
   this document. 
    
    
   5.1.  OAM Domains 
    
   As described in the previous section, a VPLS instance for a given 
   customer can span across one or more service providers and network 
   operators. Therefore, when discussing OAM tools for VPLS, e.g. 
   performance management, it is important to provide OAM capabilities 
   and functionality over each domain that a service provider or a 
   network operator is responsible for. For these reasons, it is also 
   important that OAM frames are not allowed to enter/exit other 
   domains. We define an OAM domain as a network region over which OAM 
   frames operate unobstructed as explained below.  
    
   At the edge of an OAM domain, filtering constructs should prevent 
   OAM frames from exiting and entering that domain. FM domains can be 
   nested but not overlapped. In other words, if there is a hierarchy 
   of the PM domains, the PM messages of a higher-level domain pass 
   transparently through the lower-level domains but the PM messages of 
    
     
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   a lower-level domain get blocked/filtered at the edge of that 
   domain.  
    
   In order to facilitate the processing of PM messages, we associate 
   each domain with a one-octet level at which it operates. Domains 
   with larger level numbers can contain domain with smaller level 
   numbers but the converse is not true. 
    
   A PE can be part of several domains with each interface belonging to 
   same or different domains. A PE shall block outgoing PM messages and 
   filter out incoming messages whose domain level is lower or equal to 
   the one configured on that interface and pass through the messages 
   whose domain level is greater than the one configured on that 
   interface.  
    
   Figure 2 depicts three domains: (A) customer domain which is among 
   the CEs of a given customer, (B) service provider domain which is 
   among the edge PEs of the given service provider, and (C) network 
   operator domain which is among the PEs of a given operator. 
    
           ---                                                   --- 
          /   \         ------      -------      ----           /   \ 
          |   CE--     /      \    /       \    /    \       --CE   | 
          \   /   \   /        \  /         \  /      \     /   \   / 
           ---     --UPE       NPE          NPE        UPE--     --- 
                      \        /  \         /  \      / 
                       \      /    \       /    \    /      
                        ------      -------      ---- 
    
      (A)     |<----------------------------------------------->| 
                                    customer 
    
      (B)            |<---------------------------------->| 
                                    provider  
    
      (C)            |<--------->|<----------->|<-------->| 
                       operator     operator     operator 
    
                                     Figure 2 
    
    
 
   5.2.  Maintenance & Intermediate Points 
    
   Maintenance points are responsible for origination and termination 
   of OAM/PM messages. Maintenance points are located at the edge of 
   their corresponding domains. Intermediate points are located within 
   their corresponding domains and they normally pass OAM/PM messages 
   but never initiate them. Since Maintenance points are located at the 
   edge of their domains, they are responsible for filtering outbound 
   OAM frames from leaving the domain or inbound OAM frames from 
    
     
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   entering the domain. Maintenance and intermediate points correspond 
   to a PE or more specifically to an interface of a PE. For example, 
   an OAM/PM message can be said to originate from an ingress PE or 
   more specifically an ingress interface of that PE.  
    
   Since domains are hierarchical as described above, the maintenance 
   and intermediate points that are associated with the domains become 
   hierarchical as well. A maintenance point of a higher-level domain 
   is always a maintenance point of a lower-level domain but the 
   converse is not always true since the maintenance point of lower-
   level domain can either be intermediate point or a maintenance point 
   of a higher-level domain. Furthermore, the intermediate points of a 
   lower-level domain are always transparent to the higher-level domain 
   (e.g., OAM/PM messages of a higher-level domain are not seen by 
   intermediate points of a lower-level domain and get passed through 
   them transparently). 
    
           ---                                                   --- 
          /   \         ------      -------      ----           /   \ 
          | A CE--     /      \    /       \    /    \       --CE A | 
          \   /   \   /        \  /         \  /      \     /   \   / 
           ---     --UPE       NPE          NPE        UPE--     --- 
                      \        /  \         /  \      / 
                       \      /    \       /    \    /      
                        ------      -------      ---- 
    
       (A)    CE----UPE--B--B--NPE---P--P---NPE---P----UPE----CE 
    
       (B)    E------E---E--E---E------------E----------E-----E 
                                                                
       (C)    MP----IP----------------------------------IP---MP 
                                 Customer Domain 
    
       (D)           MP---------IP-----------IP-------MP 
                                 Provider domain 
    
       (E)           MP--IP--IP--MP----------MP-------MP 
                       Operator     Operator    Operator 
                        domain       domain      domain 
    
       (F)                       MP--IP--IP--MP--IP---MP 
                                      MPLS        MPLS 
                                     domain      domain 
 
                                    Figure 3 
    
   As shown in Figure 3, (C) represents that maintenance points and 
   intermediate points that are visible within the customer domain. (D) 
   represents the maintenance points and intermediate points visible 
   within the service provider domain, while (E) represents the 
   maintenance points and intermediate points visible within each 
    
     
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   operator domain. Further, (F) represents the maintenance points and 
   intermediate points corresponding to the MPLS layer and may apply 
   MPLS based mechanisms. The MPLS layer shown in this Figure is just 
   an example and is outside the scope of this document. 
 
    
   5.2.1.  Maintenance and Intermediate Points IDs 
    
   As mentioned previously, VPLS OAM/PM should be independent of 
   underlying transport layer and should dependent on Ethernet MAC 
   layer. Therefore, at Ethernet MAC layer, the Maintenance points and 
   Intermediate points should be identified with their Ethernet MAC 
   addresses. As described in [VPLS-LDP], VPLS instance is identified 
   in an Ethernet domain (e.g., 8021.d domain) using VLAN tag (service 
   tag) while in an MPLS/IP network, PW-ids are used. Both PW-ids and 
   VLAN tags for a given VPLS instance are associated with a globally 
   unique service instance identifier (e.g., VPN identifier). 
   Maintenance and Intermediate Points ID shall be unique within their 
   corresponding domain.  
    
   Ethernet frames are used for OAM/PM messages and the source MAC 
   address of the OAM/PM frames represent the source maintenance point 
   in that domain. For Unicast OAM/PM frames, the destination MAC 
   address represents the destination maintenance point in that domain. 
   For multicast OAM/PM frames, the destination MAC addresses 
   correspond to all maintenance points in that domain. 
    
    
   6.  Performance Parameters 
    
   The following performance parameters are proposed: 
    
   6.1.  Frame Loss (FL) 
    
   Difference between the number of data frames sent from source 
   maintenance point and the number of data frames received at 
   destination maintenance point for a given VPLS instance during the 
   measurement interval.  
    
   6.2.  Frame Delay (FD) 
   Frame delay can be specified in terms of round-trip delay, which is 
   defined as the time elapsed since start of the transmission of the 
   first bit of a frame by the source maintenance point until the 
   reception of the last bit of the loop-backed frame by the same 
   source maintenance point for a given VPLS instance, when the 
   loopback is performed at the destination maintenance point. 
    
   6.3.  Frame Delay Variation (FDV) 
    
    
     
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   Frame Delay Variation can be specified in terms of variations in 
   one-way delay. Measurement of the variations in the frame arrival 
   pattern at the destination maintenance point belonging to the same 
   CoS/priority instance compared to the transmission pattern at the 
   source maintenance point for a given VPLS instance. 
    
   6.4.  Availability 
    
   Function of time the Maintenance Entity within a VPLS instance 
   (associating pair of maintenance points) is in available state. It 
   is specified as a ratio of: 
    
           Total Time ME is in Available State / Total Time 
    
   where, Total Time is number of measurement time intervals and 
   Available State is viewed as interval when network/service meets FL, 
   FD and FDV bounds. Unavailable state is encountered when at least 
   one of the FL, FD or FDV measures exceed their bounds/thresholds 
   during a time interval. These bounds/thresholds are determined by 
   the class of service (CoS).  
    
    
   6.5.  Other Parameters 
    
   These parameters are briefly introduced here and are FFS. 
    
   6.5.1.  Errored Frame Seconds (FL) 
    
   Indicates if an error (e.g., frame error due to FCS or 8B/10B coding 
   violation) has occurred within the second. This does not take into 
   consideration errors when frames are received error free but are not 
   delivered. 
    
   6.5.2.  Frame Throughput 
   Number of frames and/or bytes transmitted at a maintenance point. 
    
   6.5.3.  Frame Tx 
   Number of frames transmitted out of a maintenance point within the 
   (previous) time interval (e.g. 1 second). 
    
   6.5.4.  Frame Rx 
   Number of frames received at a maintenance point within the 
   (previous) time interval (e.g. 1 second). 
    
     
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   6.5.5.  Frame Drop 
   Number of frames dropped at a maintenance point within the 
   (previous) time interval (e.g. 1 second). 
 
 
    
   7.  Performance Measurement Mechanisms 
    
   Different measurement mechanisms are possible to perform performance 
   measurements. One significant difference across these mechanisms is 
   the level of accuracy. These mechanisms include: 
    
     - (A) Statistical Methods 
        Statistical methods use OAM frames to estimate data path 
        behavior. Such methods are least accurate since they apply 
        approximation to emulate data frames.  
      
        The limitation lies in that the behavior of actual data frames 
        may be quite different due to different addressing, processing, 
        transient congestion conditions etc. Also, error conditions in 
        networks typically happens in bursts thus statistical methods 
        can likely miss those bursts and represent different results. 
      
     - (B) Date path managed objects using management plane 
        OAM frames use data path managed objects to calculate 
        performance parameters and are inserted and/or extracted via 
        management plane. These methods are fairly accurate since they 
        use data path counters to measure data path performance.  
         
        The limitation lies in that since the insertion and extraction 
        of these OAM frames is done via management plane, in-flight 
        frames need to be accounted for. In-flight frames refer to data 
        path frames that flow between the time management plane 
        accesses data path managed objects and the time management 
        plane transmits/receives the PM OAM frame. However, this 
        limitation can be addressed by averaging such measurements 
        across multiple time intervals. 
         
     - (C) Data path managed objects using data plane 
      
        OAM frames use data path managed objects and are inserted 
        and/or extracted via data plane. This method tends to be most 
    
     
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        accurate since it does not have the limitation associated with 
        the in-flight frames. 
      
        However, the current data path hardware/chips do not support 
        the implementation of such methods since this requires Ethernet 
        data path capability to include automatic insertion and/or 
        extraction of OAM frames. Moreover, it would also require 
        changes in hardware/chips to allow ingress and egress filtering 
        rules across OAM frames to protect service provider 
        administrative domains from unintended OAM frames. 
 
   It may be noted that (B) is preferable for cases where many samples 
   are needed such as Frame Loss (FL) but in other cases such as Frame 
   Delay (FD) or Frame Delay Variation (FDV) (A) based approach can be 
   used. 
    
   Among these methods, it is recommended to use the method (B) for 
   Frame Loss (FL) since this method requires no changes in the 
   existing hardware/chips and requires only software changes for PM 
   OAM. The steps involved in such measurement mechanism include: 
    
     - Collection of managed objects information 
     - Calculation of performance parameters 
 
 
   7.1.  Performance Management Collection Method 
    
   To collect managed object information, a generic method is used to 
   collect information across different managed objects e.g. using TLVs 
   for information elements.  
 
   It is possible to use either a solicited or unsolicited collection 
   method, where solicited method requires a reply after a PM OAM 
   request message is sent while unsolicited methods does not require a 
   reply to a PM message. Current examples of solicited and unsolicited 
   methods include Loopback and CC (Continuity Check) respectively, as 
   described in [FM-SAJASSI-MOHAN]. For PM, similar methods can be 
   applied. 
    
 
   7.2.  Frame Loss Measurement 
    
    
     
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   7.2.1.  Unsolicited Method 
 
   PM OAM frame is sent every N seconds (e.g. N=1) with Frames-
   Transmitted-OK value at source maintenance point. Upon receiving 
   this PM OAM frame, Frames-Transmitted-OK value is compared with 
   Frames-Received-OK value at destination maintenance point. Between 
   two such consecutive PM OAM frames, the FL is measured as: 
 
        Frame Loss = |CT2-CT1| - |CR2-CR1|,  
 
   where CT and CR are Frames-Transmitted-OK and Frames-Received-OK 
   counts. Consecutive messages help in reducing error introduced by 
   in-flight frames and lack of timing synchronization between sender 
   and receiver. Within a measurement time interval, the FL count can 
   be averaged to improve the accuracy of measurement. 
    
   Information elements that can be applied to PM OAM Data include: 
    
     - Transaction ID 
     - Frames-Transmitted-OK TLV 
 
 
   7.2.2.  Solicited Method 
 
   Requestor sends PM OAM request frame to receiver every N seconds 
   (e.g. N=1) with its managed objects (MOs) information and expects a 
   PM OAM reply frame with receiverÆs MOs information.  
    
   Requestor sends Frames-Transmitted-OK value at source maintenance 
   point and requests Frames-Received-OK value from destination 
   maintenance point. Upon receiving the PM OAM request frame, receiver 
   compares received MO information with its corresponding MO 
   information and sends a reply PM OAM frame back to requestor with 
   requested MO information. Receiver compares received Frames-
   Transmitted-OK value with its own Frames-Received-OK value and 
   responds with its Frames-Received-OK value. Upon receiving PM OAM 
   reply frame, requestor compares originally sent value with received 
   values, similar to receiver.  
    
   It is possible that receiver returns its FL result instead of MO 
   information in response, however, if the MO information is returned, 
   the performance collection method remains generic. 
    
   Between two such consecutive PM OAM frames, the FL is measured as: 
    
    
     
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       Frame Loss = |CT2-CT1| - |CR2-CR1|,  
    
   where CT and CR are Frames-Transmitted-OK and Frames-Received-OK 
   counts. Consecutive PM OAM frames help in reducing error introduced 
   by in-flight frames and lack of timing synchronization between 
   sender and receiver. Within a measurement time interval, the FL 
   count can be averaged to improve the accuracy of this measurement. 
    
   Information elements that can be applied to PM OAM Data include: 
    
     - Transaction ID 
     - Frames-Transmitted-OK TLV 
     - Frames-Received-OK TLV 
 
 
   7.3.  Frame Delay Measurement 
    
   This method measures round-trip or two-way frame delay. Requestor 
   sends PM OAM request message with its timestamp to the receiver. 
   Receiver replies copying the requestorÆs timestamp. At the 
   requestor, the difference between the timestamps at the time of 
   receiving the PM OAM reply frame and original timestamp in the PM 
   OAM reply frame measures round trip frame delay. 
    
   Information elements that can be applied to PM OAM Data include: 
    
     - Transaction ID 
     - Request TimeStamp TLV 
    
    
   7.4.  Frame Delay Variation Measurement 
    
   This method measures round-trip or two-way frame delay per request 
   and reply frame. Within the period of observation, requestor keeps 
   track of maximum frame delay FD(max) and minimum frame delay FD(min). 
   Frame delay variation is calculated as: 
    
               Frame Delay Variation = FD(max) û FD(min) 
    
   Information elements that can be applied to PM OAM Data include: 
    
     - Transaction ID 
     - Request TimeStamp TLV 
 
 
    
     
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   7.5.  Availability Measurement 
    
   Measurement is based on FL, FD and FDV methods. Availability time 
   interval (e.g. 24hr) can be divided into measurement time intervals 
   (e.g. 1 minute). FL, FD and FDV are measured per measurement time 
   interval. If any of the three measures crosses its corresponding 
   thresholds, the measurement time interval is considered to be 
   unavailable else it is considered to be available. 
    
         Availability = (# of available measurement time intervals)/ 
                          (# of total measurement time intervals) 
 
 
   8.  Acknowledgments 
    
   We wish to thank Yoav Cohen, Marc Holness, Malcolm Betts, Paul 
   Bottorff, Norm Finn, and Monique Morrow for their valuable feedback. 
 
    
   9.  Security Considerations 
    
   Security issues resulting from this draft will be discussed in 
   greater depth at a later point.  It is recommended in [RFC3036] that 
   LDP security (authentication) methods be applied.  This would 
   prevent unauthorized participation by a PE in a VPLS.  Traffic 
   separation for a VPLS is effected by using VC labels.  However, for 
   additional levels of security, the customer MAY deploy end-to-end 
   security, which is out of the scope of this draft.  In addition, the 
   L2FRAME] document describes security issues in greater depth. 
    
    
   10.  Intellectual Property Considerations 
    
   This document is being submitted for use in IETF standards 
   discussions. 
    
    
   11.  Full Copyright Statement 
    
   Copyright (C) The Internet Society (2001).  All Rights Reserved.  
   This document and translations of it may be copied and furnished to 
   others, and derivative works that comment on or otherwise explain it 
   or assist in its implementation may be prepared, copied, published 
   and distributed, in whole or in part, without restriction of any 
   kind, provided that the above copyright notice and this paragraph 
   are included on all such copies and derivative works.  However, this 
   document itself may not be modified in any way, such as by removing 
   the copyright notice or references to the Internet Society or other 
   Internet organizations, except as needed for the purpose of 
    
     
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   developing Internet standards in which case the procedures for 
   copyrights defined in the Internet Standards process must be 
   followed, or as required to translate it into languages other than 
   English. 
    
   The limited permissions granted above are perpetual and will not be 
   revoked by the Internet Society or its successors or assigns. 
    
   This document and the information contained herein is provided on an 
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 
   TASK FORCE DISCLAIMS 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.         References 
    
   [PWE3-ETHERNET] "Encapsulation Methods for Transport of Ethernet 
   Frames Over IP/MPLS Networks", draft-ietf-pwe3-ethernet-encap-
   01.txt, Work in progress, November 2002. 
    
   [802.1D-ORIG] Original 802.1D - ISO/IEC 10038, ANSI/IEEE Std 802.1D-
   1993 "MAC Bridges". 
    
   [802.1D-REV] 802.1D - "Information technology - Telecommunications 
   and information exchange between systems - Local and metropolitan 
   area networks - Common specifications - Part 3: Media Access Control 
   (MAC) Bridges: Revision. This is a revision of ISO/IEC 10038: 1993, 
   802.1j-1992 and 802.6k-1992. It incorporates P802.11c, P802.1p and 
   P802.12e." ISO/IEC 15802-3: 1998. 
    
   [802.1Q] 802.1Q - ANSI/IEEE Draft Standard P802.1Q/D11, "IEEE 
   Standards for Local and Metropolitan Area Networks: Virtual Bridged 
   Local Area Networks", July 1998. 
    
   [VPLS-REQ] "Requirements for Virtual Private LAN Services (VPLS)", 
   draft-ietf-ppvpn-vpls-requirements-01.txt, Work in progress, October 
   2002. 
    
   [L2FRAME] "L2VPN Framework", draft-ietf-ppvpn-l2-framework-03, Work 
   in Progress, February 2003. 
    
   [802.1ad] ôIEEE standard for Provider Bridges, Work in Progress, 
   December 2002ö 
    
   <To be updated in the next Rev.> 
    
 
   13.  Authors' Addresses 
    
   Dinesh Mohan                       Ali Sajassi 
    
     
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   Nortel Networks                    Cisco Systems, Inc. 
   3500 Carling Ave.                  170 West Tasman Drive 
   Ottawa, ON  K2H 8E9                San Jose, CA 95134 
   Email: mohand@nortelnetworks.com   Email: sajassi@cisco.com 
 
   Vasile Radoaca                     Norm Finn 
   Nortel Networks                    Cisco Systems, Inc. 
   600 Technology Park                170 West Tasman Drive 
   Billerica, MA 01821                San Jose, CA 95134 
   Email: vasile@nortelnetworks.com   Email: nfinn@cisco.com 
                 
   Shahram Davari                     Yoav Cohen 
   PMC Sierra                         Native Networks 
   411 Legget Drive  
   Ottawa, ON K2K 3C9  
   Email: shahram_davari@pmc-sierra.com 
    
     
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