Network Working Group Y. El Mghazli, Ed.
Request for Comments: 4176 Alcatel
Category: Informational T. Nadeau
Cisco
M. Boucadair
France Telecom
K. Chan
Nortel
A. Gonguet
Alcatel
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).
Abstract
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
document.
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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
follows:
VPN:
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
[RFC4026].
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L3VPN:
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.
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.
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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
configurations.
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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
agreement.
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
management);
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
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- - - - - - - - - - - - - - - - - - - - - - - -:- - - - - - - - -
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
structure.
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
VPN.
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.
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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
(SLS).
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)
parameters:
o QoS and traffic parameters
o Availability for the site, VPN, or access connection
o Duration of outage intervals per site, route, or VPN
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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
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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
Manager
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].
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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
phase.
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.
2.2.5.1. 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.
2.2.5.2. Authentication
Authentication is the process of verifying the identity of a VPN
user.
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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
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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)
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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
Manager.
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
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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
configurable.
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
membership.
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.
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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.
3.2.2.1. 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.
3.2.2.2. Provisioning Access-based Configuration Information
The Provider Network Manager must provision network access between
SP-managed PE and CE equipment.
3.2.2.3. 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.
3.2.2.4. 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
purposes.
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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.
3.2.2.5. 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
party.
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.
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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.
3.2.2.6. 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
monitored.
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
configurable.
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].
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3.2.5.1. 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
integrity).
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.
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RFC 4176 L3VPN Operations and Management Framework October 2005
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
2000.
[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.
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RFC 4176 L3VPN Operations and Management Framework October 2005
[Y.1311] ITU, "Network-based IP VPN over MPLS architecture",
ITU-T Y.1311.1, 2001.
Authors' Addresses
Yacine El Mghazli (Editor)
Alcatel
Route de Nozay
Marcoussis 91460
France
EMail:
[email protected]
Thomas D. Nadeau
Cisco Systems, Inc.
300 Beaver Brook Road
Boxborough, MA 01719
Phone: +1-978-936-1470
EMail:
[email protected]
Mohamed Boucadair
France Telecom
42, rue des Coutures
Caen 14066
France
EMail:
[email protected]
Kwok Ho Chan
Nortel Networks
600 Technology Park Drive
Billerica, MA 01821
USA
EMail:
[email protected]
Arnaud Gonguet
Alcatel
Route de Nozay
Marcoussis 91460
France
EMail:
[email protected]
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RFC 4176 L3VPN Operations and Management Framework October 2005
Full Copyright Statement
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