Internet DRAFT - draft-ietf-ppvpn-as-vr
draft-ietf-ppvpn-as-vr
Provider Provisioned VPN WG Ananth Nagarajan
Internet Draft Consultant
draft-ietf-ppvpn-as-vr-02.txt
Category: Informational
Expiration Date: December 2003 Junichi Sumimoto
Muneyoshi Suzuki
NTT Corporation
Paul Knight
Nortel Networks
Benson Schliesser
SAVVIS Communications
July 2003
Applicability Statement for Virtual Router-based Layer 3 PPVPN approaches
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of [RFC-2026].
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Abstract
This document is an applicability statement for Layer 3 Provider
Provisioned VPNs (L3 PPVPNs) that is based on Virtual Router (VR)
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approaches. This document describes how VR-based approaches meet
the key requirements that are outlined in the PPVPN Applicability
Statements Guideline document.
Table of Contents
1. Introduction .................................... 3
2. SP Provisioning Model ........................... 4
2.1. Auto Discovery .................................. 4
3. Supported Topology and Traffic Types ............ 5
4. Isolated Exchange of Routing and
Data Information ................................ 5
4.1. Isolation of Routing Information (constrained
distribution of reachability information) ....... 6
4.2. Isolation of data ............................... 7
5. Access Control and Authentication ............... 7
6. Security ........................................ 8
6.1. Protection of User Data ......................... 8
6.2. SP Security Measures ............................ 8
7. Addressing ...................................... 9
8. Interoperability and Interworking ............... 10
9. Network Access .................................. 10
9.1. Physical and Link Layer Topology ................ 10
9.2. Temporary Access ................................ 10
9.3. Access Connectivity ............................. 10
10. Service Access .................................. 11
10.1. Internet Access ................................. 11
10.2. Hosting, ASP, other services .................... 11
11. SP Routing ...................................... 11
11.1. Core Router Awareness of Mechanisms Used ........ 12
12. Migration Impacts ............................... 13
13. Scalability ..................................... 14
14. QoS/SLA ......................................... 15
15. SLA Monitoring .................................. 16
16. Management ...................................... 16
16.1. SP Management of Customer Site .................. 16
16.2. Customer Management of VR ........................ 17
16.3. SP Network Management ............................ 17
17. Security Considerations ......................... 18
18. Acknowledgments ................................. 18
19. References ....................................... 18
19.1. Normative References ............................ 18
19.2. Informative References .......................... 18
20. Authors' Addresses .............................. 19
21. Full Copyright Statement ........................ 20
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1. Introduction
The virtual router concept for L3 PPVPNs was first introduced in
[COREVPN]. This was generalized in [PPVPNVR]. A number of
autodiscovery mechanisms can be used with this approach to L3 PPVPNs,
and [COREVPN] represents one such approach using IP multicast. Based
on the taxonomy of PPVPNs described in [FRAMEWORK], Virtual Router
based approaches are classified as PE-based Layer 3 PPVPNs.
VR-based PPVPNs are used in the following situations:
- The customer wishes to outsource the maintenance and management of
inter-site VPN connectivity to the Service Provider (SP).
- The SP desires to provide VPN service without upgrading its core
network to support any specific technology (e.g., MPLS), i.e., the SP
wants to provide a Layer 3 VPN service over a range of core network
technologies, including existing IP routed or Layer 2 switched core
networks, MPLS, or a combination of these technologies.
- The customer is not aware of the topology or mechanisms used in the
SP core network and is responsible for routing between customer
routers, which is independent of the routing used in the SP core.
Only the customer-facing sides of the PE devices in the SP network
are visible to the customer.
- The customer wishes to exercise control of routing functions at the
CE routers at each of its VPN sites, while depending on the SP to
provide transport for data traffic and for the customers routing
information across the SP core. From the viewpoint of any of the
customers routers, there will usually appear to be a single router
hop to any other VPN site. The only routes exchanged between the CE
routers and the PE devices are the customers internal routes (with
the possible addition of routes desired by the customer for Internet
access via the SP, such as a default route).
- The customer sends IP traffic across the VPN, possibly including
non-IP traffic encapsulated in IP by the customer.
- The VPN service provider does not own a backbone network but wishes
to provide PPVPN services over a backbone obtained from some other
provider.
- Several cooperating SPs desire to offer PPVPN service at points
that span multiple administrataive domains of the backbone, perhaps
over the public Internet.
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This document describes how Virtual Router based approaches satisfy
key requirements and metrics identified in the PPVPN Applicability
Statements Guideline document [ASGUIDE]. These requirements are a
subset of the requirements listed in the PPVPN Service Requirements
document [REQTS]. This document is based on the guidelines specified
in [ASGUIDE].
2. SP Provisioning Model
Virtual Routers (VRs) can interact with other routers so as to be
indistinguishable from an individual physical router. However,
multiple instances of VRs can be configured within a single physical
device, providing a significant improvement in manageability and
provisioning flexibility, compared with multiple physical routers.
Each VR can maintain its own separate routing tables, so if two
virtual routers are in the same physical router, an
interaction of one VR with one of its peers does not have any effect
on the interaction of another VR with any of its own peers. In some
implementations, VRs may share physical interface bandwidth.
VPNs are constructed via tunnels connecting VR pairs across the
service provider backbone network. Per-VR routing protocol
instantiations are run to distribute VPN reachability information.
VPN membership information distribution is treated separately, and is
achieved via sharing a VPN-ID, for example [RFC2685], between VRs
that are members of a specific VPN. The detailed VR model is
described in [PPVPNVR].
2.1. Auto Discovery
In the VR-based PPVPNS, various auto discovery mechanisms are
supported. VPN discovery can be achieved through directory servers
[RADIUS-DISC], explicit configuration via a management platform,
using multicast [COREVPN] or by piggybacking VPN membership and
topology information via routing protocols such as BGP [VPN-BGP]. A
combination of these mechanisms may also be used on a PE. For
example, for some VPNs topology discovery is done only through a
management platform. For others, dynamic topology discovery is
achieved using existing routing protocol. BGP-based auto-discovery
is described in [VPN-BGP], and may be used for membership and
topology discovery.
It is important to note that, for the VR architecture, the auto-
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discovery mechanism is only used to automatically exchange control
VPN information between VRs. It is not intended for interchange of
the VPN routing information, which is accomplished by standard
routing protocols running between the VRs, as discussed in [PPVPNVR].
3. Supported Topology and Traffic Types
VR-based PPVPNs can be constructed using either MPLS or IP tunnels
(GRE, IP-in-IP, L2TP, IPSec) in the core network, or Layer 2
connections such as ATM or Frame Relay. The choice of the tunneling
mechanism may impact other properties of the VPN itself, including
scalability, manageability, QoS, security, etc. For example, the
use of IPSec tunnels for encryption may impact forwarding performance
on some devices, and therefore impact the number of sites or routes
per VPN, the number of VPNs per PE, etc. The performance of IPSec
tunnels may be improved through the use of dedicated hardware, which
allows greater performance and scaling but potentially at increased
cost.
Tunnels are created on a per-VPN basis. For transport across the
network, a number of these tunnels may be aggregated and carried
within a PE-PE tunnel. The SP has a high degree of flexibility in
configuring the topology of a VPN interconnecting customer sites.
The topology can be full-mesh, partial-mesh, or any arbitrary
topology that has been agreed to by the customer and the SP.
4. Isolated exchange of routing and data information
By definition of a Virtual Private Network, the details of its
addressing, topology, connectivity, and reachability as well as the
data that it transports are implicitly considered to be private, and
should therefore be isolated from other networks, including others
that may be supported with the PPVPN infrastructure. [FRAMEWORK]
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4.1. Isolation of routing information (constrained distribution of
reachability information)
In any PPVPN, the SP is responsible for maintaining isolation between
networks except as explicitly intended by the VPN owner.
The VR model of PPVPNs provides for isolation by instantiating
multiple Virtual Routers (VR) on a single physical platform to
support multiple VPNs. [PPVPNVR] Each VR has its own logical
interfaces, routing tables, forwarding tables, and routing protocol
instances. Note that a VR may share physical interfaces with other
VRs, depending on the implementation and specific topology. This
provides for isolated topology, addressing, and reachability for the
VPN.
Addressing and Reachability includes the assignment, discovery, and
distribution of source and/or destination information for the PPVPN.
The isolation of this information implies that other networks,
including other VPNs and the Internet, will have no visibility into
the PPVPN except as explicitly configured.
Routing information carried between VRs is carried in through the
same tunnels as data itself, and is therefore segregated from the
underlying backbone infrastructure by the same mechanisms that
segregate data between VPNs.
This model supports arbitrary routing architectures, including
support for back-door links among customer VPN sites or other
potentially unique routing architecture requirements. The support
for arbitrary routing architectures, however, is accompanied by
scalability and management issues. These issues are discussed later
in this document.
In the VR approach, virtual routers are connected to the CEs through
local links, and to each other across the backbone through tunneling
services provided by the service provider across the backbone. All
data traffic within the VR-based VPN is isolated from non-VPN traffic
by these mechanisms.
Some VR implementations may provide the ability for customers to
exercise limited management operations upon the VRs which are
connected to the customer CEs. This may allow the customer to view
routing tables, or traffic statistics, or to exercise some control
over the customers routing. VRs MUST NOT allow any customer to
circumvent the isolation of routing or data among VPNs.
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4.2. Isolation of data
Data for different VPNs in the VR model is segregated through the use
of different link-layer connections or tunnels over a common SP
backbone. [PPVPNVR] Examples of such tunnels include GRE, L2TP,
IPSec, MPLS or Layer 2 connections such as ATM or Frame Relay. It
should be noted that this isolation can be impacted by
misconfiguration.
5. Access Control and Authentication
CE-PE authentication has not been specified for VR-based VPNs. PE/CE
mutual authentication may be done via any mechanism supported by the
routing protocol in which the CE and PE are peers (e.g., use of the
TCP MD5 authentication when the CE/PE protocol is BGP), or by any
other mechanism that may be desired by the customer.
In order for VR-based PPVPNs to support confidentiality, integrity,
authentication, and replay attack prevention, mechanisms such as
IPsec may be used as tunneling mechanism or used over VPN tunnels.
Even with the use of IPsec, the security level offered is dependent
on the scope of the IPsec security associations: encrypting on a CE-
to-CE basis (as in CE-based VPNs) will offer a wider scope of
protection than only encrypting on a PE-to-PE basis (as in PE-based
VPNs), since the CE-PE link remains unencrypted in the latter case.
However, PE-PE IPsec offers substantial advantages in efficiency,
outsourcing, and integration with the dynamic membership and dynamic
routing nature of the PPVPN. CE-PE IPsec can also be used to protect
traffic on the CE-PE section of the network. In this case the
traffic is only unprotected by IPsec within the PE device. Policy-
based security and access control mechanisms or firewalls may be used
between sites in the same VPN. These can be implemented on the PE
router, or on the CE.
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6. Security
6.1. Protection of user data
As described above, end-to-end (CE-to-CE) IPSec may be used to
protect user data. SPs may choose to provide CE-based IPSec as a
value added service. If the SP core network is also part of the
public Internet, the SP may choose to provide PE-to-PE IPSec as the
tunneling mechanism between VRs.
If inter-SP VPNs are to be provided, IPSec tunnels may be used. The
impact on QoS and SLAs in this case will have to be studied.
In general, user data is protected via the inherent isolation
provided by the inter-VR tunnels. Varying levels of security of user
data may be provided based on the type of tunnel that is used.
6.2. SP Security Measures
In general, the SP should ensure that non-VPN traffic does not
accidentally or maliciously enter a VPN. Since VRs can be configured
very specifically for a customer, the SP can offer customers anti-
spoofing or other traffic or route filtering services tailored for
the customers network. The SP's PE and P devices should be protected
against intrusion or denial of service attacks. This is especially
important because the SP core network may be used to provide general
Internet services apart from VPN services. Therefore any Denial of
Service attack or misconfiguration that impacts other VPN services
and Internet services should be prevented. Since most of the traffic
from CE to PE, apart from control (routing and network management)
traffic, gets encapsulated to be carried across the SP network, the
possibility of users sending traffic to other (non-PE) systems in the
core network is minimized or eliminated. The inherent isolation of VR
mechanisms helps provide this protection against attacks from
customer sites, but additional specific measures are available:
- VR routing sessions can be authenticated between the PE and CE, and
among PEs.
- If BGP is used as an auto-discovery mechanism between VRs, it
should be further authenticated using mechanisms such as TCP MD5.
- Filtering of any management data entering the PE should be
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performed in order to prevent the acceptance of unauthorized packets
from customers or other SPs into that PE.
Denial of Service attacks may occur via routing traffic or network
management traffic, either intentionally or accidentally via routing
instabilities or misconfigurations in the VPN. With Virtual router
VPNs, in many cases a dynamic routing protocol will be run between CE
routers and VRs within PE routers. Either the same or a different
dynamic routing protocol may be run between VR instances in each PE
associated with a VPN. If routing is unstable in the private network,
it is possible for this instability to propagated to the PE routers.
For example, in some cases a large number of routing updates could be
sent from the CE router to a VR within a PE router, or between VR
instances in different PE routers. This could potentially place a
major or excessive processing load on the PE routers.
This issue can be mitigated via resource partitioning in the PE, in
order to limit the amount of resources (e.g., CPU and memory) which
any one VR is permitted to use in PE routers. Also, rate limits may
be applied to the routing traffic sent from the CE to the PE.
Alternately, when this problem is detected on the CE to PE link, the
CE to PE interface may be shut down.
In order to prevent DoS attacks due to network management traffic,
the functions available to the customer need to be strictly
controlled. It may also be useful to limit the resource use of this
capability. Resource partitioning may be appropriate internal to PE
routers, and network management traffic from the CE to the PE may be
rate limited (for example,to prevent network management traffic from
CE to PE to be used in a DOS attack).
7. Addressing
Virtual routers may provide any or all of the services which are
provided by a physical router, including Network Address Translation
(NAT), packet filtering, etc. These VR capabilities can simplify the
process of joining previously independent site networks, which may
have overlapping address spaces. NAT can be used to satisfy intra-
VPN non-unique addressing requirements. This facilitates the
construction of short-term or ad-hoc VPNS. It should be noted,
however, that NAT has accompanying scaling problems, and other
mechanisms are needed to ensure proper routing updates, when two
sites share the same routing domain.
Non-unique and private customer addresses may be supported by using
encapsulation within the tunneling mechanisms employed between VR
pairs (e.g., GRE, IP-in-IP etc.). As such, support for private
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addressing as specified in [RFC1918] allows for non-unique addresses
between different VPNs.
8. Interoperability and Interworking
Interoperability and Interworking of VR-based VPNs with other L3
PPVPN mechanisms such as 2547bis is for further study. Since VRs
provide all IP router functionalities, various VR-based solutions
interwork and interoperate to the extent that IP networks
interoperate and interwork.
9. Network Access
9.1. Physical and Link Layer Topology
VR-based mechanisms do not affect the choice of physical and link
layer technologies or topologies.
9.2. Temporary Access
Temporary access for a dial-up user to a VR can be provided via PPP
and AAA, using a Remote Access Server. Other access mechanisms such
as IPSec can also be used. Thus, it is possible provide login and
password based access to a VR-based VPN from an authorized user
connected to the Internet.
9.3. Access Connectivity
Multi-homing of CEs to multiple VRs (within the same or different
PEs) is supported. The PEs (and consequently the VRs) may belong to
different SPs.
Load sharing based on IGP or other traffic engineering mechanisms
used in the SP core are naturally supported by VR-based VPNs.
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10. Service Access
10.1. Internet Access
Simultaneous VPN and Internet Access can be supported via various
mechanisms. A specific VR may be assigned as a default VR that is
connected to the Internet. If a single VR is to be used to carry a
customer's VPN as well as Internet traffic, Internet traffic can be
distinguished from VPN traffic by associating a default VPN-ID with
Internet traffic and pointing it to a default route to the Internet.
This default route to the Internet need not be direct, but may
instead point to a firewall or other security device which may use
different interfaces for VPN access and Internet access.
10.2. Hosting, ASP, other services
All of the above "external" services can be supported by associating
a separate address for every service that is not being used within
the VPN. If a single server (for example, a web hosting server) is
used to provide a particular service to all VPNs, NAT may be used to
provide a unique address for clients to access that particular
service. NAT can be performed either at the customer site or can be
integrated into the PE. The scaling impacts of adding NAT to the PE
will have to be considered.
11. SP Routing
VR-based PPVPNs do not impose any additional requirements on the IGP
used in the service provider core network. However, if the customer
VPN runs an IGP, the VRs (and consequently the PEs) must support that
IGP. This customer IGP need not be the same as the IGP running in the
Service Provider's core network.
>From the customers viewpoint of its VPN IGP routing topology (if it
uses one), the SPs network topology appears much simpler than it may
actually be. Depending on the VR implementation, the SPs service
offering, and the SPs physical topology, it may appear as either a
single large router with interfaces for each VPN site, as a full
mesh, with two routers between any two sites, as a hub-and spoke
topology (when the customer wants all inter-site traffic to pass
through one or more specific sites, for application of services such
as security filtering), or other arbitrary topology. In general, the
SP's actual core routing topology is invisible to the customer.
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Fault handling is a specific problem when the timers used for the VR-
to-VR routing peering are shorter than the timers used for the
routing peering within the service provider(s) network. In this case
a single failure within a service provider network may look like a
collection of un-correlated failures in the VPN.
Moreover, since a VR doesn't really "know" what causes the failure,
the VR may react to such a failure by re-routing along some other
tunnel, while this other tunnel may be also affected by the same
failure. As a result, this would slow down routing convergence within
the VPN.
To avoid the problems mentioned above one may consider making the
timers used for the VR-to-VR peering longer than the timers used for
the routing peering within the service provider network (so that
failures within the service provider network would be "invisible" to
the VR-VR tunnels). But that has its own set of problems. While
this may be possible to accomplish within a single routing domain
(one needs to appropriately set the IGP timers within the domain),
doing this in a network that includes more than one routing domain
may be difficult (as timers include both IGP and BGP timers, and
moreover, timers include IGP timers in several routing domains).
Another consequence of making the timers used for the VR-to-VR
peering over the tunnels longer than the timers used for the routing
peering within the service provider network is that it would increase
the amount of traffic that will be "black holed" in the case of VR
failures.
A key aspect of the issue here is that layer 3 problems in the SP
network may appear as layer 2 problems in the VPN. Thus stability of
the SP network, with an emphasis on quick recovery, is a key element
in delivering satisfactory service.
Prevention of Denial of Service attacks caused by routing
instabilities has been discussed in Section 6.2.
11.1. Core router awareness of mechanisms used
Since tunnels are established between VR pairs, the core router (P
router) does not have any information of the mechanisms used to
construct the VPN. If MPLS is the tunneling mechanism that is used
between the VRs, the core routers may have to be MPLS enabled in
order to leverage the benefits of MPLS tunnels (e.g., traffic
engineering). As such, while the core routers are not aware of VPN-
specific information, they should support requirements to meet
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relevant SLAs. (e.g., for guaranteed QoS, the core routers may need
to support appropriate QoS mechanisms).
12. Migration impacts
Similar to other Layer 3 PPVPN architectures, any CE using services
provided using the VR approach can access a PE similar to the way it
would access another CE router in a private network using leased
lines. As the VR approach makes use of standard routing protocols
without any extensions, there is no requirement for additional
capabilities on the part of CEs in order to interoperate with a VR-
based PPVPN.
Key design considerations include:
- The PEs will introduce extra router hops
- If the VR-VR backbone routing protocol differs from the sites, then
IGP metric implications should be carefully evaluated. This would be
particularly true for multihomed VPN sites.
In general, a VR-based PPVPN offers the customer a greatly simplified
network topology compared to a customer-managed private network,
since each CE router sees a single link as the next-hop route to all
other VPN sites. There is no need to configure multiple physical or
logical interfaces on the CE routers.
Multi-homed VPN sites or sites with back-door connections will
involve design decisions as to whether each of the multiple links
should operate as a backup link or as a load-sharing link.
Also, since the VR approach does not depend on the backbone
architecture in terms of routing protocols, a VR-based L3 PPVPN can
be offered on a service provider core network without the need for
specific core technologies. For example, the core network does not
need specific mechanisms like MPLS to be implemented on the P
routers. Similarly, if the core network is a Layer 2 network based
on ATM or Frame Relay, VR-based VPNs can still be constructed.
It should be noted, however, that core network mechanisms would
determine the overall properties and services that may be provided
over the VPN. For example, in order to support customer QoS SLAs,
the core network should be robustly engineered or should support QoS
mechanisms, in addition to SLA marking at the PE.
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Thus, while migration impacts in the case of basic VPN functionality
using VR are minimal from the customers' or providers' point of view,
appropriate core mechanisms may be necessary for certain services.
13. Scalability
PE-based PPVPNs have better scalability than CE-based PPVPNs, because
the total number of VPN tunnels that need to be managed are far fewer
in the service provider backbone, than between CEs. Addition of a
new CE in a CE-based PPVPN would require O(N^2) tunnels to be set up
where N represents the total number of CEs. In comparison, addition
of a new CE for a specific customer, in the case of a PE-based PPVPN,
would simply require an additional connection between the new CE and
the PE, because inter-PE tunnels already exist per VPN.
VR is a technology for implementing logical routing instances in a PE
device. A PE device may contain more than one VR and a VR supports
one VPN. Therefore, scalability of a VR and conventional physical
router are basically the same, e.g., if different routing protocols
are used for customer and network sides of a VR or physical router,
the load is increased compared with the case when the same protocols
are used.
The major factor contributing to scalability constraint in the VR
approach is the number of VRs which can be supported by a PE. This is
because, the number of VRs in a PE device is equal to the number of
VPNs which are supported by the PE.
Resources used by a VR instance include memory and processor
resources, used to support VPN tunnel mechanisms, routing protocol
instances, route tables, interface management, etc. The extent to
which these resources are utilized impact scalability.
Much of the resource utilization for a given VPN will be affected by
the topology of the VPN. For instance, a VPN with a full-mesh
topology will require that VRs have more peers for the VPN tunneling
mechanism, for routing protocol adjacencies, for security protocols,
etc., while a hub-and-spoke model will constrain the resources
required for 'spoke' PE routers.
>From a VR perspective, scalability also depends on whether the same
routing protocols are used between VRs as in the backbone network. If
the inter-VR routing protocols are different from the backbone IGP,
the scaling and management impacts for configuring routing protocols
on a per-VR basis may be significant. For example, it may be
necessary to maintain OSPF databases for the entire customer VPN
topology, as opposed to maintaining information for only directly
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connected customer sites. Additionally, the customer IGP may need to
maintain information about the entire VR topology, for the VRs which
are connected to the customer's CEs. Other concerns include routing
loop avoidance, route redistribution, etc. Thus, while the VR model
allows the routing protocols between customers and VRs to be
different than the backbone IGP, this flexibility can be accompanied
by scalability concerns. Mechanisms such as OSPF areas may be used
to circumvent such scaling issues.
It is normal in many cases for a VR located in a PE router to run a
routing instance with each other VR which is part of the same VPN. In
some cases this could result in a large number of routing
adjacencies. The number of routing adjacencies could aggravate the
impact of instability in routing in the private network, or aggravate
the impact of routing protocol DOS attack described in Section 6.2.
As mentioned in Section 6.2, this can be mitigated by appropriate
resource partitioning in the PE, and by rate limiting of routing
packets,including packets from CE to PE and well as packets from PE
to PE. Also, while this consideration may limit the number of VRs
which may potentially be supported from a single PE device, it does
not have any significant effect on the overall scaling of a network
implementing the VR approach.
14. QoS/SLA
VR-based PPVPNs support any kind of QoS that the core network and the
tunneling mechanism used support.
VR-based VPNs can utilize different quality of service mechanisms.
QoS mechanisms developed for physical routers can be used with VRs,
on a per-VR basis. e.g. classification, policing, drop policies,
traffic shaping and scheduling/bandwidth reservation. The
architecture allows separate quality of service engineering of the
VPNs and the backbone. However, the tunneling mechanisms themselves
should support relevant QoS mechanisms.
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15. SLA Monitoring
VR-based VPNs can implement a variety of methods to monitor
compliance with Service Level Agreements. Since the links between
VRs make use of tunnels across the underlying backbone network, the
SLA monitoring capabilities of the backbone network can be used to
monitor the performance of the inter-VR links. Because the inter-VR
links are tunnels, and the SLA monitoring capabilities of the
backbone network may not include "per tunnel" monitoring
capabilities, some VR implementations support additional SLA
monitoring mechanisms. Performance to SLA requirements within the PEs
hosting the VRs is typically monitored via internal processes to
ensure compliance from end to end. In addition, either the service
provider or the VPN customer can use all existing SLA tracking tools
(round trip time measurement, traceroute mapping, etc.) within the
VR-based VPN.
16. Management
16.1. SP Management of customer site
The SP may choose to manage the customer site (i.e., the CE devices)
for added revenue. If the SP uses a centralized customer management
system, care should be taken to uniquely identify various CEs
belonging to different VPNs, so that CE devices from different VPNs
do not reach each other.
The customer may desire to have access to the PE device for
monitoring purposes (e.g., ping, traceroute). Providing such access
is at the discretion of the SP.
Traffic statistics in order to prove SLAs to customers may be
provided on a periodic basis. Other statistics that can show
enhanced SP capabilities, including protection against Denial of
Service attacks, failure etc., can be provided to the customer.
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16.2. Customer Management of VR
Some VR implementations may provide the ability for customers to
exercise limited management operations upon the VRs which are
connected to the customer CEs. This may allow the customer to view
routing tables, or traffic statistics, or to exercise some control
over the customers routing.
Customer network management and troubleshooting systems will
generally have less ability to gather information from the VRs than
from the customers own routers, and will also have little or no
ability to directly change VR configurations. The customers systems
should be planned so as to accommodate the restricted capabilities of
the VRs to respond to customer network management processes.
Prevention of Denial of Service attacks due to network management
traffic originating from customer management of the VR has been
discussed in Section 6.2.
16.3. SP Network Management
When an SP provides VR-based VPN services, it is highly likely that
the PE devices used are complex because of the number of VRs
supported, the number of routing adjacencies between VR pairs,
maintenance of tunnel and VPN-specific information and possibly other
information such as QoS. Thus the management of the PE is extremely
critical for the SP. If the SP core is also used to provide Internet
services, adequate mechanisms should be in place in order to not
allow misconfigurations or instabilities in the PE control plane to
affect the general Internet operations or impact other VPN customers.
In addition to normal SP network management, prevention of Denial of
Service attacks must be in place in the PEs. Resource partitioning
and rate limiting, as described in Section 6.2 are examples of such
mechanisms.
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17. Security considerations
There are no additional security considerations besides those already
addressed in the document in Section 6.
18. Acknowledgments
The authors of this draft would like to acknowledge the suggestions
and comments received from the entire Layer 3 Applicability Statement
Design Team formed in the PPVPN working group. Besides the authors,
the members of the design team include Marco Carugi, Eric Rosen,
Jeremy De Clercq, Luyuan Fang, Dave McDysan, Cliff Wang, Olivier
Paridaens, Tom Nadeau, Yakov Rekhter and Rick Wilder. Thanks are also
due to the authors of [PPVPNVR], especially Hamid Ould-Brahim. Many
thanks are due to the constructive comments made by Ross Callon and
Mark Duffy.
19. REFERENCES
19.1. Normative References
[PPVPNVR] Ould-Brahim, H., et al., "Network based IP VPN Architecture
using Virtual Routers", work in progress.
[RFC2026] Bradner, S., "The Internet Standards Process -- Revision
3", RFC 2026, October 1996.
19.2. Informative References
[ASGUIDE] Sumimoto, J., et al., "Guidelines of Applicability
Statements for PPVPNs," work in progress.
[FRAMEWORK] R. Callon, et al., "A Framework for Layer 3 Provider
Provisioned Virtual Private Networks," work in progress.
[REQTS] McDysan, D., et al., "Service requirements for Layer 3
Provider Provisioned Virtual Private Networks", work in progress.
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[RFC2764] Gleeson, B., et al., "A Framework for IP Based Virtual
Private Networks", RFC 2764, February 2000.
[RFC1918] Rekhter, Y. et al., "Address Allocation for Private
Internets," RFC 1918, February 1996.
[RFC2685] Fox B., et al, "Virtual Private Networks Identifier", RFC
2685, September 1999.
[COREVPN] Muthukrishnan, K., Malis, A., "Core MPLS IP VPN
Architecture", work in progress.
[RFC2547bis] Rosen E., et al, "BGP/MPLS VPNs", work in progress.
[VPN-BGP] Ould-Brahim, H., et al, "Using BGP as an Auto-Discovery
Mechanism for Network-based VPNs", work in progress.
[RADIUS-DISC] Heinanen J., "Using Radius for PE-Based VPN Discovery",
work in progress.
20. Authors' Addresses
Ananth Nagarajan
Consultant
E-mail: ananth@maoz.com
Muneyoshi Suzuki
Junichi Sumimoto
NTT Information Sharing Platform Labs.
3-9-11, Midori-cho,
Musashino-shi, Tokyo 180-8585, Japan
Email: suzuki.muneyoshi@lab.ntt.co.jp
Email: sumimoto.junichi@lab.ntt.co.jp
Paul Knight
Nortel Networks
600 Technology Park Drive
Billerica, MA 01821
E-mail: paknight@nortelnetworks.com
Benson Schliesser
SAVVIS Communications
717 Office Parkway
St. Louis, MO 63141
Phone: +1-314-468-7036
Email: bensons@savvis.net
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21. Full Copyright Statement
Copyright (C) The Internet Society (2003). 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
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.
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