faqs.org - Internet FAQ Archives

RFC 4176 - Framework for Layer 3 Virtual Private Networks (L3VPN

Or Display the document by number

Network Working Group                                 Y. El Mghazli, Ed.
Request for Comments: 4176                                       Alcatel
Category: Informational                                        T. Nadeau
                                                            M. Boucadair
                                                          France Telecom
                                                                 K. Chan
                                                              A. Gonguet
                                                            October 2005

        Framework for Layer 3 Virtual Private Networks (L3VPN)
                       Operations and Management

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).


   This document provides a framework for the operation and management
   of Layer 3 Virtual Private Networks (L3VPNs).  This framework intends
   to produce a coherent description of the significant technical issues
   that are important in the design of L3VPN management solutions.  The
   selection of specific approaches, and making choices among
   information models and protocols are outside the scope of this

Table of Contents

   1.  Introduction .................................................  2
       1.1.  Terminology ............................................  2
       1.2.  Management functions ...................................  4
       1.3.  Reference Models .......................................  5
   2.  Customer Service Operations and Management ...................  7
       2.1.  Customer Service Management Information Model ..........  7
       2.2.  Customer Management Functions ..........................  8
             2.2.1.  Fault Management ...............................  8
             2.2.2.  Configuration Management .......................  9
             2.2.3.  Accounting .....................................  9
             2.2.4.  Performance Management ......................... 10
             2.2.5.  Security Management ............................ 10
       2.3.  Customer Management Functional Description ............. 11
             2.3.1.  L3VPN Service Offering Management .............. 11
             2.3.2.  L3VPN Service Order Management ................. 12
             2.3.3.  L3VPN Service Assurance ........................ 12
   3.  Provider Network Manager ..................................... 12
       3.1.  Provider Network Management Definition ................. 12
       3.2.  Network Management Functions ........................... 13
             3.2.1.  Fault Management ............................... 13
             3.2.2.  Configuration Management ....................... 14
             3.2.3.  Accounting ..................................... 17
             3.2.4.  Performance Management ......................... 17
             3.2.5.  Security Management ............................ 17
   4.  L3VPN Devices ................................................ 18
       4.1.  Information Model ...................................... 18
       4.2.  Communication .......................................... 18
   5.  Security Considerations ...................................... 19
   6.  Acknowledgements ............................................. 19
   7.  Normative References ......................................... 19

1.  Introduction

1.1.  Terminology

   In this document, the following terms are used and defined as


      Virtual Private Network.  A set of transmission and switching
      resources that will be used over a shared infrastructure to
      process the (IP) traffic that characterizes communication services
      between the sites or premises interconnected via this VPN.  See


      An L3VPN interconnects sets of hosts and routers based on Layer 3
      addresses.  See [RFC4026].

   VPN Instance:

      From a management standpoint, a VPN instance is the collection of
      configuration information associated with a specific VPN, residing
      on a PE router.

   VPN Site:

      A VPN customer's location that is connected to the Service
      Provider network via a CE-PE link, which can access at least one

   VPN Service Provider (SP):

      A Service Provider that offers VPN-related services.

   VPN Customer:

      Refers to a customer that bought VPNs from a VPN service provider.

   Customer Agent:

      Denotes the entity that is responsible for requesting VPN
      customer-specific information.

   Service Level Agreement(SLA):

      Contractual agreement between the Service Provider and Customer,
      which includes qualitative and quantitative metrics that define
      service quality guarantees and retribution procedures when service
      levels are not being met.

   Service Level Specifications (SLS):

      Internally-focused service performance specifications used by the
      Service Provider to manage customer service quality levels.

1.2.  Management functions

   For any type of Layer-3 VPN (PE or CE-based VPNs), having a
   management platform where the VPN-related information could be
   collected and managed is recommended.  The Service and Network
   Management System may centralize information related to instances of
   a VPN and allow users to configure and provision each instance from a
   central location.

   An SP must be able to manage the capabilities and characteristics of
   their VPN services.  Customers should have means to ensure
   fulfillment of the VPN service to which they subscribed.  To the
   extent possible, automated operations and interoperability with
   standard management protocols should be supported.

   Two main management functions are identified:

   A customer service management function:

      This function provides the means for a customer to query,
      configure, and receive (events/alarms) customer-specific VPN
      service information.  Customer-specific information includes data
      related to contact, billing, site, access network, IP address,
      routing protocol parameters, etc.  It may also include
      confidential data, such as encryption keys.  Several solutions
      could be used:

      *  Proprietary network management system

      *  SNMP manager

      *  PDP function

      *  Directory service, etc.

   A provider network management function:

      This function is responsible for planning, building, provisioning,
      and maintaining network resources in order to meet the VPN
      service-level agreements outlined in the SLA offered to the
      customer.  This mainly consists of (1) setup and configuration of
      physical links, (2) provisioning of logical VPN service
      configurations, and (3) life-cycle management of VPN service,
      including the addition, modification, and deletion of VPN

      There may be relationships between the customer service and
      provider network management functions, as the provider network is
      managed to support/realize/provide the customer service.  One
      example use of this relationship is to provide the VPN-SLS
      assurance for verifying the fulfillment of the subscribed VPN

1.3.  Reference Models

   The ITU-T Telecommunications Management Network has the following
   generic requirements structure:

   o  Engineer, deploy and manage the switching, routing, and
      transmission resources supporting the service from a network
      perspective (network element management);

   o  Manage the VPNs deployed over these resources (network

   o  Manage the VPN service (service management);

      - - - - - - - - - - - - - - - - - - - - - - - -:- - - - - - - - -
      Service      +-------------+                   :      +----------+
      Management   |   Service   |<------------------:----->| Customer |
      Layer        |   Manager   |                   :      | Agent    |
                   +-------------+                   :      +----------+
      - - - - - - - - - - ^ - - - - - - - - - - - - -:- - - - - - - - -
      Network             |       +------------+     :
      Management          |       |  Provider  |     :
      Layer               |       |  Network   |  Customer
                          +------>|  Manager   |  Interface
                                  +------------+     :
      - - - - - - - - - - - - - - - - - ^ - - - - - -:- - - - - - - - -
      Network Element                   |            :
      Management                        |  +------+  :  +------+
      Layer                             |  |      |  :  |  CE  |
                                        +->|  PE  |  :  |device|
                                           |device|  :  |  of  |
                                           |      |--:--|VPN  A|
                                           +------+  :  +------+
                     SP network                      :  Customer Network

          Figure 1: Reference Model for PE-based L3VPN Management

      - - - - - - - - - - - - - - - - - - - - - - - -:- - - - - - - - -
      Service      +-------------+                   :      +----------+
      Management   |   Service   |<------------------:----->| Customer |
      Layer        |   Manager   |                   :      | Agent    |
                   +-------------+                   :      +----------+
      - - - - - - - - - - ^ - - - - - - - - - - - - -:- - - - - - - - -
      Network             |       +------------+     :
      Management          |       |  Provider  |     :
      Layer               |       |  Network   |  Customer
                          +------>|  Manager   |  Interface
                                  +------------+     :
      - - - - - - - - - - - - - - - -^- - - -^- - - -:- - - - - - - - -
      Network Element                |       +-------:---------------+
      Management                     |     +------+  :  +------+     |
      Layer                          |     |      |  :  |  CE  |     |
                                     +---->|  PE  |  :  |device|<----+
                                           |device|  :  |  of  |
                                           |      |--:--|VPN  A|
                                           +------+  :  +------+
                     SP network                      :  Customer Network

          Figure 2: Reference Model for CE-based L3VPN Management

   Above, Figures 1 and 2 present the reference models for both PE and
   CE-based L3VPN management, according to the aforementioned generic

   In both models, the service manager administrates customer-specific
   attributes, such as customer Identifier (ID), personal information
   (e.g., name, address, phone number, credit card number, etc.),
   subscription services and parameters, access control policy
   information, billing and statistical information, etc.

   In the PE-based reference model, the provider network manager
   administrates device attributes and their relationships, covering PE
   devices and other devices that construct the corresponding PE-based

   In the CE-based reference model, the provider network manager
   administrates device attributes and their relationships, covering PE
   and CE devices that construct the corresponding CE-based VPN.

   Network and customer service management systems that are responsible
   for managing VPN networks have several challenges, depending on the
   type of VPN network(s) they are required to manage.

2.  Customer Service Operations and Management

   Services offered by providers can be viewed from the customer's or
   the provider's perspective.  This section describes service
   management from the customer's perspective, focusing on the Customer
   Management function.

   The Customer Management function's goal is to manage the
   service-based operations like service ordering, service subscription,
   activation, etc.

   The Customer Management function resides in the L3VPN service manager
   at the Service Management Layer (SML).  It mainly consists of
   defining the L3VPN services offered by the SP, collecting and
   consolidating the customer L3VPN services requirements, as well as
   performing some reporting for the customer.  This function is
   correlated with the Network Management function at the Network
   Management Layer (NML) for initiating the L3VPN services
   provisioning, and getting some service reporting.

2.1.  Customer Service Management Information Model

   This section presents a framework that is used for L3VPN customer
   service management at the SML.  The information framework represents
   the data that need to be managed, and the way they are represented.
   At the SML, the information framework that is foreseen is composed of
   Service Level Agreements (SLA) and Service Level Specifications

   Services are described through Service Level Agreements (SLA), which
   are contractual documents between customers and service providers.
   The technical part of the service description is called the Service
   Level Specification (SLS).  The SLS groups different kinds of
   parameters.  Some are more related to the description of the
   transport of the packets, and some to the specification of the
   service itself.

   A Service Level Specification (SLS) may be defined per access network
   connection, per VPN, per VPN site, and/or per VPN route.  The service
   provider may define objectives and the measurement intervals, for at
   least the SLS, using the following Service Level Objective (SLO)

   o  QoS and traffic parameters

   o  Availability for the site, VPN, or access connection

   o  Duration of outage intervals per site, route, or VPN

   o  Service activation interval (e.g., time to turn up a new site)

   o  Trouble report response time interval

   o  Time to repair interval

   o  Total incoming/outgoing traffic from a site or a (VPN) route, or
      that has transited through the whole VPN

   o  Measurement of non-conforming incoming/outgoing traffic
      (compliance of traffic should deserve some elaboration because of
      many perspectives - security, QoS, routing, etc.) from a site or a
      (VPN) route, or that has transited through the whole VPN

   The service provider and the customer may negotiate contractual
   penalties in the case(s) where the provider does not meet a (set of)
   SLS performance objective(s).

   Traffic parameters and actions should be defined for incoming and
   outgoing packets that go through the demarcation between the service
   provider premises and the customer's premises.  For example, traffic
   policing functions may be activated at the ingress of the service
   provider's network, while traffic shaping capabilities could be
   activated at the egress of the service provider's network.

2.2.  Customer Management Functions

   This section presents detailed customer management functions in the
   traditional fault, configuration, accounting, performance, and
   security (FCAPS) management categories.

2.2.1.  Fault Management

   The fault management function of the Customer Service Manager relies
   upon the manipulation of network layer failure information, and it
   reports incidents to the impacted customers.  Such reports should be
   based upon and related to the VPN service offering to which the
   customer is subscribed.  The Customer Management function support for
   fault management includes:

   o  Indication of customer's services impacted by failure

   o  Incident recording or logs

   o  Frequency of tests

   o  Ability to invoke probes from the customer and provider

   o  Ability to uncover faults before the customer notices them

2.2.2.  Configuration Management

   The configuration management function of the Customer Manager must be
   able to configure L3VPN service parameters with the level of detail
   that the customer is able to specify, according to service templates
   defined by the provider.

   A service template contains fields which, when instantiated, yield a
   definite service requirement or policy.  For example, a template for
   an IPsec tunnel [RFC2401] would contain fields such as tunnel end
   points, authentication modes, encryption and authentication
   algorithms, shared keys (if any), and traffic filters.

   Other examples: a BGP/MPLS-based VPN service template would contain
   fields such as the customer premises that need to be interconnected
   via the VPN, and a QoS agreement template would contain fields such
   as one-way transit delay, inter-packet delay variation, throughput,
   and packet loss thresholds.

2.2.3.  Accounting

   The accounting management function of the Customer Manager is
   provided with network layer measurements information and manages this
   information.  The Customer Manager is responsible for the following
   accounting functions:

   o  Retrieval of accounting information from the Provider Network

   o  Analysis, storage, and administration of measurements

   Some providers may require near-real time reporting of measurement
   information, and may offer this as part of a customer network
   management service.

   If an SP supports "Dynamic Bandwidth Management" service, then the
   schedule and the amount of the bandwidth required to perform
   requested bandwidth allocation change(s) must be traceable for
   monitoring and accounting purposes.

   Solutions should state compliance with accounting requirements, as
   described in section 1.7 of [RFC2975].

2.2.4.  Performance Management

   From the Customer Manager's perspective, performance management
   includes functions involved in the determination of the conformance
   level with the Service Level Specifications, such as QoS and
   availability measurements.  The objective is to correlate accounting
   information with performance and fault management information to
   produce billing that takes into account SLA provisions for periods of
   time where the service level objectives are not met.

   The performance information should reflect the quality of the
   subscribed VPN service as perceived by the customer.  This
   information could be measured by the provider or controlled by a
   third party.  The parameters that will be used to reflect the
   performance level could be negotiated and agreed upon between the
   service provider and the customer during the VPN service negotiation

   Performance management should also support analysis of important
   aspects of an L3VPN, such as bandwidth utilization, response time,
   availability, QoS statistics, and trends based on collected data.

2.2.5.  Security Management

   From the Customer Manager's perspective, the security management
   function includes management features to guarantee the security of
   the VPN.  This includes security of devices, configuration data, and
   access connections.  Authentication and authorization (access
   control) also fall into this category.  Access Control

   Management access control determines the privileges that a user has
   for particular applications and parts of the network.  Without such
   control, only the security of the data and control traffic is
   protected (leaving the devices providing the L3VPN network
   unprotected) among other equipment or resources.  Access control
   capabilities protect these devices to ensure that users have access
   to only those resources and applications they are granted to use.  Authentication

   Authentication is the process of verifying the identity of a VPN

2.3.  Customer Management Functional Description

   This section provides a high-level example of an architecture for the
   L3VPN management framework, with regard to the SML layer.  The goal
   is to map the customer management functions described in Section 2.2
   to architectural yet functional blocks, and to describe the
   communication with the other L3VPN management functions.

       + - - - - - - - - - - - - - - - - - - - - - - - - -  +
       | Service    +----------------+   +----------------+ |
       | Management |   VPN  Offering|   | VPN Order      | |
       |            |   Management   |   |    Management  | |
       |            +----------------+   +----------------+ |
       |            +----------------+   +----------------+ |
       |            |   VPN          |   | VPN-based      | |
       |            |   Assurance    |   | SLS Management | |
       |            +----------------+   +----------------+ |
       + - - - - - - - - - - - - - - - - - - - - - - - - -  +

            Figure 3: Overview of the Service Management

   A customer must have a means to view the topology, operational state,
   order status, and other parameters associated with the VPN service
   offering that has been subscribed.

   All aspects of management information about CE devices and customer
   attributes of an L3VPN, manageable by a SP, should be capable of
   being configured and maintained by an authenticated, authorized
   Service manager.

   A customer agent should be able to make dynamic requests for changing
   the parameters that describe a service.  A customer should be able to
   receive responses from the SP network in response to these requests
   (modulo the existence of necessary agreements).  Communication
   between customer Agents and (VPN) service providers will rely upon a
   query/response mechanism.

   A customer who may not be able to afford the resources to manage its
   CPEs should be able to outsource the management of the VPN to the
   service provider(s) supporting the network.

2.3.1.  L3VPN Service Offering Management

   Hopefully, the deployment of a VPN addresses customers' requirements.
   Thus, the provider must have the means to advertise the VPN-based
   services it offers.  Then, the potential customers could select the
   service to which they want to subscribe.  Additional features could
   be associated to this subscription phase, such as the selection of a

   level of quality associated to the delivery of the VPN service, the
   level of management of the VPN service performed by the SP, security
   options, etc.

2.3.2.  L3VPN Service Order Management

   This operation aims at managing the requests initiated by the
   customers and tracks the status of the achievement of the related
   operations.  The activation of the orders is conditioned by the
   availability of the resources that meet the customer's requirements
   with the agreed guarantees (note that it could be a result of a
   negotiation phase between the customer and the provider).

2.3.3.  L3VPN Service Assurance

   The customer may require the means to evaluate the fulfillment of the
   contracted SLA with the provider.  Thus, the provider should monitor,
   measure, and provide statistical information to the customer,
   assuming an agreement between both parties on the measurement
   methodology, as well as the specification of the corresponding (set
   of) quality of service indicators.

3.  Provider Network Manager

3.1.  Provider Network Management Definition

   When implementing a VPN architecture within a domain (or a set of
   domains managed by a single SP), the SP must have a means to view the
   physical and logical topology of the VPN premises, the VPN
   operational status, the VPN service ordering status, the VPN service
   handling, the VPN service activation status, and other aspects
   associated with each customer's VPN.

   From a provider's perspective, the management of a VPN service
   consists mainly of:

   o  Managing the customers (the term "customer" denotes a role rather
      than the end user, thus an SP could be a customer) and end-users
      in terms of SLA

   o  Managing the VPN premises (especially creating, modifying, and
      deleting operations, editing the related information to a specific
      link, or supervising the AAA [RFC2903] [RFC2906] operations)

   o  Managing the CE-PE links (particularly creating, modifying, and
      deleting links, editing the related information to a specific VPN)

   o  Managing the service ordering, such as Quality of Service, in
      terms of supported classes of service, traffic isolation, etc.

   Currently, proprietary methods are often used to manage VPNs.  The
   additional expense associated with operators having to use multiple,
   proprietary, configuration-related management methods (e.g., Command
   Line Interface (CLI) languages) to access such systems is not
   recommended, because it affects the overall cost of the service
   (including the exploitation costs), especially when multiple vendor
   technologies (hence multiple expertise) are used to support the VPN
   service offering.  Therefore, devices should provide standards-based
   interfaces.  From this perspective, additional requirements on
   possible interoperability issues and availability of such
   standardized management interfaces need to be investigated.

3.2.  Network Management Functions

   In addition, there can be internal service provided by the SP for
   satisfying the customer service requirements.  Some of these may
   include the notion of dynamic deployment of resources for supporting
   the customer-visible services, high availability service for the
   customer that may be supported by automatic failure detection, and
   automatic switchover to back-up VPNs.  These are accomplished by
   inter-working with the FCAPS capabilities of the Provider Network

3.2.1.  Fault Management

   The Provider Network Manager support for fault management includes:

   o  Fault detection (incidents reports, alarms, failure visualization)

   o  Fault localization (analysis of alarms reports, diagnostics)

   o  Corrective actions (data path, routing, resource allocation)

   Since L3VPNs rely upon a common network infrastructure, the Provider
   Network Manager provides a means to inform the Service Manager about
   the VPN customers impacted by a failure in the infrastructure.  The
   Provider Network Manager should provide pointers to the related
   customer configuration information to contribute to the procedures of
   fault isolation and the determination of corrective actions.

   It is desirable to detect faults caused by configuration errors,
   because these may cause VPN service to fail, or not meet other
   requirements (e.g., traffic and routing isolation).  One approach

   could be a protocol that systematically checks that all constraints
   have been taken into account, and that consistency checks have been
   enforced during the tunnel configuration process.

   A capability that aims at checking IP reachability within a VPN must
   be provided for diagnostic purposes.

   A capability that aims at checking the configuration of a VPN device
   must be provided for diagnostic purposes.

3.2.2.  Configuration Management

   The Provider Network Manager must support configuration management
   capabilities in order to deploy VPNs.  To do so, a Provider Network
   Manager must provide configuration management that provisions at
   least the following L3VPN components: PE, CE, hierarchical tunnels,
   access connections, routing, and QoS, as detailed in this section.
   If access to the Internet is provided, then this option must also be

   Provisioning for adding or removing VPN customer premises should be
   as automated as possible.

   Finally, the Provider Network Manager must ensure that these devices
   and protocols are provisioned consistently and correctly.  The
   solution should provide a means for checking whether a service order
   is correctly provisioned.  This would represent one method of
   diagnosing configuration errors.  Configuration errors can arise due
   to a variety of reasons: manual configuration, intruder attacks, and
   conflicting service requirements.

   Requirements for L3VPN configuration management are:

   o  The Provider Network Manager must support configuration of VPN

   o  The Provider Network Manager should use identifiers for SPs,
      L3VPNs, PEs, CEs, hierarchical tunnels, and access connections.

   o  Tunnels must be configured between PE/CE devices.  This requires
      coordination of tunnel identifiers, paths, VPNs, and any
      associated service information, for example, a QoS service.

   o  Routing protocols running between PE routers and CE devices must
      be configured.  For multicast services, multicast routing
      protocols must also be configurable.

   o  Routing protocols running between PE routers, and between PE and P
      routers, must also be configured.

   PE-based only:

   o  Routing protocols running between PE routers and CE devices, if
      any, must be configured on a per-VPN basis.  The Provider Network
      Manager must support configuration of a CE routing protocol for
      each access connection.

   o  The configuration of a PE-based L3VPN should be coordinated with
      the configuration of the underlying infrastructure, including
      Layer 1 and 2 networks that interconnect components of an L3VPN.  Provisioning Routing-based Configuration Information

   If there is an IGP running within the L3VPN, the Provider Network
   Manager must provision the related parameters.  This includes
   metrics, capacity, QoS capability, and restoration parameters.  Provisioning Access-based Configuration Information

   The Provider Network Manager must provision network access between
   SP-managed PE and CE equipment.  Provisioning Security Services-based Configuration Information

   When a security service is requested, the Provider Network Manager
   must provision the entities and associated parameters involved in the
   provisioning of the service.  For example, IPsec services, tunnels,
   options, keys, and other parameters should be provisioned at either
   the CE and/or the PE routers.  In the case of an intrusion detection
   service, the filtering and detection rules should be provisioned on a
   VPN basis.  Provisioning VPN Resource Parameters

   A service provider should have a means to dynamically provision
   resources associated with VPN services.  For example, in a PE-based
   service, the number and size of virtual switching and forwarding
   table instances should be provisioned.

   If an SP supports a "Dynamic Bandwidth Management" service, then the
   dates, times, amounts, and intervals required to perform requested
   bandwidth allocation change(s) may be traceable for accounting

   If an SP supports a "Dynamic Bandwidth Management" service, then the
   provisioning system must be able to make requested changes within the
   ranges and bounds specified in the Service Level Specifications.
   Examples of QoS parameters are the response time and the probability
   of being able to service such a request.

   Dynamic VPN resource allocation is crucial to cope with the frequent
   requests for changes that are expressed by customers (e.g., sites
   joining or leaving a VPN), as well as to achieve scalability.  The PE
   routers should be able to dynamically assign the VPN resources.  This
   capability is especially important for dial-up and wireless VPN
   services.  Provisioning Value-Added Service Access

   An L3VPN service provides controlled access between a set of sites
   over a common backbone.  However, many service providers also offer a
   range of value-added services, for example: Internet access, firewall
   services, intrusion detection, IP telephony and IP Centrex,
   application hosting, backup, etc.  It is outside the scope of this
   document to define if and how these different services interact with
   the VPN service offering.  However, the VPN service should be able to
   provide access to these various types of value-added services.

   A VPN service should allow the SP to supply the customer with
   different kinds of well-known IP services (e.g., DNS, NTP, RADIUS,
   etc.) needed for ordinary network operation and management.  The
   provider should be able to provide IP services to multiple customers
   from one or many servers.

   A firewall function may be required to restrict access to the L3VPN
   from the Internet [Y.1311].

   Managed firewalls may be supported on a per-VPN basis, although
   multiple VPNs will be supported by the same physical device.  In such
   cases, managed firewalls should be provided at the access point(s) of
   the L3VPN.  Such services may be embedded in the CE or PE devices, or
   implemented in stand-alone devices.

   The Provider Network Manager should allow a customer to outsource the
   management of an IP service to the SP providing the VPN or to a third

   The management system should support the collection of information
   necessary for optimal allocation of IP services in response to
   customers' orders, in correlation with provider-provisioned resources
   supporting the service.

   If Internet access is provided, reachability to and from the Internet
   from/to sites within a VPN should be configurable by an SP.
   Configuring routing policy to control distribution of VPN routes
   advertised to the Internet may realize this.  Provisioning Hybrid VPN Services

   Configuration of interworking L3VPN solutions should also be
   supported, taking security and end-to-end QoS issues into account.

3.2.3.  Accounting

   The Provider Network Manager is responsible for the measurements of
   resource utilization.

3.2.4.  Performance Management

   From the Provider Network Manager's perspective, performance
   management includes functions involved in monitoring and collecting
   performance data regarding devices, facilities, and services.

   The Provider Network Manager must monitor the devices' behavior to
   evaluate performance metrics associated with an SLS.  Different
   measurement techniques may be necessary, depending on the service for
   which an SLA is provided.  Example services are QoS, security,
   multicast, and temporary access.  These techniques may be either
   intrusive or non-intrusive, depending on the parameters being

   The Provider Network Manager must also monitor aspects of the VPN
   that are not directly associated with an SLS, such as resource
   utilization, status of devices and transmission facilities, as well
   as control of monitoring resources, such as probes and remote agents
   at network access points used by customers and mobile users.

   Devices supporting L3VPN whose level of quality is defined by SLSes
   should have real-time performance measurements that have indicators
   and threshold crossing alerts.  Such thresholds should be

3.2.5.  Security Management

   From the Provider Network Manager's perspective, the security
   management function of the Provider Network Manager must include
   management features to guarantee the preservation of the
   confidentiality of customers' traffic and control data, as described
   in [RFC3809].  Authentication Management

   The Provider Network Manager must support standard methods for
   authenticating users attempting to access VPN services.

   Scalability is critical, as the number of nomadic/mobile clients is
   increasing rapidly.  The authentication scheme implemented for such
   deployments must be manageable for large numbers of users and VPN
   access points.

   Support for strong authentication schemes needs to be supported to
   ensure the security of both VPN access point-to-VPN access point (PE
   to PE) and client-to-VPN Access point (CE-to-PE) communications.
   This is particularly important to prevent VPN access point (VPN AP)
   spoofing.  VPN Access Point Spoofing is the situation where an
   attacker tries to convince a PE or a CE that the attacker is the VPN
   Access Point.  If an attacker succeeds, then the device will send VPN
   traffic to the attacker (who could forward it on to the actual (and
   granted) access point after compromising confidentiality and/or

   In other words, a non-authenticated VPN AP can be spoofed with a man-
   in-the-middle attack, because the endpoints rarely verify each other.
   A weakly authenticated VPN AP may be subject to such an attack.
   However, strongly authenticated VPN APs are not subject to such
   attacks, because the man-in-the-middle cannot authenticate as the
   real AP, due to the strong authentication algorithms.

4.  L3VPN Devices

4.1.  Information Model

   Each L3VPN solution must specify the management information (MIBs,
   PIBs, XML schemas, etc.) for network elements involved in L3VPN
   services.  This is an essential requirement in network provisioning.
   The approach should identify any L3VPN-specific information not
   contained in a standards track MIB module.

4.2.  Communication

   The deployment of a VPN may span a wide range of network equipment,
   potentially including equipment from multiple vendors.  Therefore,
   the provisioning of a unified network management view of the VPN
   shall be simplified by means of standard management interfaces and
   models.  This will also facilitate customer self-managed (monitored)
   network devices or systems.

   In cases where significant configuration is required whenever a new
   service is to be provisioned, it is important, for scalability
   reasons, that the NMS provides a largely automated mechanism for the
   relevant configuration operations.  Manual configuration of VPN
   services (i.e., new sites, or re-provisioning existing ones) could
   lead to scalability issues, and should be avoided.  It is thus
   important for network operators to maintain visibility of the
   complete picture of the VPN through the NMS system.  This should be
   achieved by using standards track protocols such as SNMP.  Use of
   proprietary command-line interfaces is not recommended.

5.  Security Considerations

   This document describes a framework for L3VPN Operations and
   Management.  Although this document discusses and addresses some
   security concerns in Section 2.2.5 and Section 3.2.5 above, it does
   not introduce any new security concerns.

6.  Acknowledgements

   Special Thanks to Nathalie Charton, Alban Couturier, Christian
   Jacquenet, and Harmen Van Der Linde for their review of the document
   and their valuable suggestions.

7.  Normative References

   [RFC2975]  Aboba, B., Arkko, J., and D. Harrington, "Introduction to
              Accounting Management", RFC 2975, October 2000.

   [RFC2401]  Kent, S. and R. Atkinson, "Security Architecture for the
              Internet Protocol", RFC 2401, November 1998.

   [RFC2903]  de Laat, C., Gross, G., Gommans, L., Vollbrecht, J., and
              D. Spence, "Generic AAA Architecture", RFC 2903, August

   [RFC2906]  Farrell, S., Vollbrecht, J., Calhoun, P., Gommans, L.,
              Gross, G., de Bruijn, B., de Laat, C., Holdrege, M., and
              D. Spence, "AAA Authorization Requirements", RFC 2906,
              August 2000.

   [RFC3809]  Nagarajan, A., "Generic Requirements for Provider
              Provisioned Virtual Private Networks (PPVPN)", RFC 3809,
              June 2004.

   [RFC4026]  Andersson, L. and T. Madsen, "Provider Provisioned Virtual
              Private Network (VPN) Terminology", RFC 4026, March 2005.

   [Y.1311]   ITU, "Network-based IP VPN over MPLS architecture",
              ITU-T Y.1311.1, 2001.

Authors' Addresses

   Yacine El Mghazli (Editor)
   Route de Nozay
   Marcoussis  91460

   EMail: yacine.el_mghazli@alcatel.fr

   Thomas D. Nadeau
   Cisco Systems, Inc.
   300 Beaver Brook Road
   Boxborough, MA  01719

   Phone: +1-978-936-1470
   EMail: tnadeau@cisco.com

   Mohamed Boucadair
   France Telecom
   42, rue des Coutures
   Caen  14066

   EMail: mohamed.boucadair@francetelecom.com

   Kwok Ho Chan
   Nortel Networks
   600 Technology Park Drive
   Billerica, MA  01821

   EMail: khchan@nortel.com

   Arnaud Gonguet
   Route de Nozay
   Marcoussis  91460

   EMail: arnaud.gonguet@alcatel.fr

Full Copyright Statement

   Copyright (C) The Internet Society (2005).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an

Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at ietf-


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


User Contributions:

Comment about this RFC, ask questions, or add new information about this topic: