Provider Provisioned VPN WG Hamid Ould-Brahim Internet Draft Bryan Gleeson draft-ouldbrahim-vpn-vr-03.txt Gregory Wright Expiration Date: September 2001 Nortel Networks Timon Sloane Webstacks Rainer Bach T-Data Rick Bubenik SAVVIS Communications Abraham Young Huawei Technologies Jieyun Jessica Yu Chandru Sargor Cosine Communications Luyuan Fang AT&T March 2001 Network based IP VPN Architecture using Virtual Routers Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [RFC-2026]. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract Ould-Brahim, et. al [Page 1] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 This draft describes a network based VPN architecture using virtual routers. The VPN service is built based on the virtual router (VR) concept, which has exactly the same mechanisms as a physical router, and therefore inherits all existing mechanisms and tools for configuration, operation, accounting, and maintenance. Within a VPN domain, an instance of routing is used to distribute VPN reachability information among VR routers. Any routing protocol can be used, and no VPN-related modifications or extensions are needed to the routing protocol for achieving VPN reachability. Virtual routers can be deployed in different VPN configurations, direct VR to VR connectivity through layer-2 or by aggregating multiple VRs into a single VR combined with IP or MPLS based tunnels. This architecture accommodates different backbone deployment scenarios, e.g. where the VPN service provider owns the backbone, and where the VPN service provider obtains backbone service from one or more other service providers. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119. Table of Contents 1 Introduction ........................................ 3 2 Virtual Router Architecture Requirements ............. 4 2.1 Membership .......................................... 4 2.2 Scalability .......................................... 4 2.3 Quality of Service ................................... 4 2.4 Auto-Discovery ....................................... 5 2.5 Routing .............................................. 5 2.5.1 Routing between PE and CE ............................ 5 2.5.2 Routing in the Service Provider Network .............. 5 2.5.3 Routing between PEs................................... 5 2.6 Security ............................................. 5 2.7 Topology ............................................. 5 2.8 Tunneling ............................................ 5 2.9 Management ........................................... 5 2.10 General Requirements ................................. 5 3 Network Reference Model .............................. 6 3.1 The Backbone ........................................ 7 4 Virtual Router Definition ............................ 7 5 How VPNs are built and deployed using VRs?............ 8 5.1 VR to VR Connectivity over layer-2 Connections........ 8 5.2 Virtual Router Backbone Aggregation .................. 8 5.2.1 Tunneling ............................................ 9 5.2.1.1 MPLS Tunnels ...................................... 9 5.2.1.2 IPSec Tunnels ..................................... 9 5.2.2 Routing .............................................. 10 5.2.3 Relationship between the VRs and the Backbone VR ..... 10 5.2.4 Multiple Backbones connected to a single PE .......... 10 6 VPN Auto-Discovery ................................... 11 Ould-Brahim, et al. March 2001 [Page 2] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 7 VRs and Extranets .................................... 12 8 VPNs across Domains .................................. 12 9 Internet Access ...................................... 13 10 Carrier's Carrier Case................................ 13 11 Operations and Management ............................ 13 11.1 Backbone Migration ................................... 14 11.2 Troubleshooting ...................................... 14 12 Quality of Service ................................... 14 13 Scalability .......................................... 15 14 Security Considerations .............................. 15 15 References............................................ 15 16 Acknowledgments ..................................... 16 17 Authors' Addresses .................................. 16 1. Introduction Several solutions have been put forward to achieve different levels of network privacy when building VPNs across a shared IP backbone. Most of these solutions require separate per VPN forwarding capabilities and make use of IP or MPLS based tunnels across the backbone [VPN-RFC2764], [VPN-CORE], and [VPN-RFC2547]. This document describes a network based VPN architecture using virtual routers. The architecture complies with the IP VPN framework described in [VPN-RFC2764]. The objective is to provide per VPN based routing, forwarding, quality of service, and service management capabilities. The VPN service is built based on the virtual router concept, which has exactly the same mechanisms as a physical router, and therefore inherits all existing mechanisms and tools for configuration, deployment, operation, troubleshooting, monitoring, and accounting. Virtual routers can be deployed in different VPN configurations, direct VR to VR connectivity through layer-2 links/tunnels or by aggregating multiple VRs into a single VR combined with IP or MPLS based tunnels. This architecture accommodates different backbone deployment scenarios, e.g. where the VPN service provider owns the backbone, and where the VPN service provider obtains backbone service from one or more other service providers. Within a VPN domain, an instance of routing is used to distribute VPN reachability information among VR routers. Any routing protocol can be used, and no VPN-related modifications or extensions are needed to the routing protocol for achieving VPN reachability. VPN reachability information to and from customer sites can be dynamically learned from the CE using standard routing protocols or it can be statically provisioned on the VR. The routing protocol between the virtual routers and CEs is independent of the routing used in the VPN backbone. The routing protocol between the VRs maybe the same or it might be different than the routing mechanism used between the CE and VR. Ould-Brahim, et al. March 2001 [Page 3] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 There are two fundamental architectures for implementing network based VPNs, virtual routers (VR) and piggybacking. The main difference between the two architectures resides in the model used to achieve VPN reachability and membership functions. In the VR model, each VR in the VPN domain is running an instance of routing protocol responsible to disseminate VPN reachability information between VRs. Therefore, VPN membership and VPN reachability are treated as separate functions, and separate mechanisms are used to implement these functions. VPN reachability is carried out by a per- VPN instance of routing, and a range of mechanisms is possible for determining membership (see section 6.0). In the piggyback model the VPN network layer is terminated at the edge of the backbone, and a backbone routing protocol (i.e. BGP-4) is responsible for disseminating the VPN membership and reachability information between provider edge routers (PE) for all the VPNs configured on the PE. [VPN-RFC2547bis] is an example of a piggyback VPN architecture. 2. Virtual Router Architecture Requirements This section lists some requirements addressed by the proposed VR architecture. 2.1 Membership All virtual routers that are members of a specific VPN MUST share the same VPN-ID. A recommended VPN identifier (VPN-ID) format to be used is defined in the standard RFC2685. 2.2 Scalability In this architecture, the backbone internal nodes are not required to be VPN aware or VR aware, and therefore they don't keep any VPN state within the backbone. However, in the case where the internal nodes are also VR aware then it is possible to have either tunnels from the PE or the CE connecting to the internal VRs. This type of VPN deployment can be useful when the internal nodes are geographically suitable to be the VPN hub. 2.3 Quality of Service Existing quality of service mechanisms developed for physical routers should all be available to be used per VR basis. Therefore, quality of service (policing/shaping/classification/scheduling) SHOULD be configurable per VPN basis. 2.4 Auto-discovery It should be possible for the VRs to automatically discover each other, setup tunnels to each other, and exchange private routing information across the backbone. It is required that the auto- discovery mechanism take into consideration of the case where the Ould-Brahim, et al. March 2001 [Page 4] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 VPNs are implemented across domains. We assume in this document that BGP as described in [VPN-BGP] is used as the mechanism to distribute membership, topology, and tunnel information among VRs members of the same VPN. 2.5 Routing 2.5.1 Routing between PE and CE Any existing routing protocol in the VPN domain can be used between PE and the CE. 2.5.2 Routing in the Service Provider Network (Backbone) The choice of the backbone routing protocol should not be constrained by the VPNs. 2.5.3 Routing between PEs Any existing routing protocol in the VPN domain can be used between PEs. 2.6 Security The architecture MUST accommodate different levels of data and routing security. The architecture must provide authentication and encryption services for VPNs requiring strong security capabilities. 2.7 Topology VPN topologies like a hub and spoke, and full mesh MUST be supported. Furthermore, it should be possible to build arbitrary VPN topologies. 2.8 Tunneling The architecture should not be limited to a single tunneling mechanism. It should be possible to use per VPN basis, IPSec, GRE, IP in IP, and MPLS tunnels, as it should also be possible to support shared tunnels between VPNs. Therefore within a single VPN, different type of tunnels can be used. 2.9 Management It should be easy to configure, deploy, operate and troubleshoot each VPN independently using existing mechanisms and tools. Tools used for operating, managing and debugging IP networks can continue to be used without any modification. 2.10 General Requirements Ould-Brahim, et al. March 2001 [Page 5] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 The followings are some general requirements for the VR architecture: (a) The architecture should accommodate different sizes of VPNs, and one VPN should not impact other VPNs on the PE. (b) The architecture MUST support overlapping VPN address spaces in separate VPNs. (c) The architecture should support direct paths between VPN sites that bypass the service provider backbone (backdoor links). Traffic can be directed to the backdoor link, or injected to the backbone with the flexibility of using both the backbone access, and the backdoor link as internal or external paths. (d) The architecture MUST work over different deployment scenarios, e.g. where the service provider owns their own backbone, and where the service provider obtains backbone service from one or more other service providers. 3. Network Reference Model A VPN customer site is connected to the provider backbone by means of a connection between a CE device, (which can either be a bridge or a router) and a virtual router. CE devices are preconfigured to connect to one (or more) VR(s).Multiple virtual routers coexist on the same service provider edge device (PE). CE devices can be attached to VRs over any type of access link (e.g. ATM, frame relay, ethernet, PPP or IP tunneling mechanism such as IPSec, L2TP or GRE tunnels). +---+ +---+ | P |....| P | +---+ +---+ PE / \ PE +----+ +------+ +------+ +---+ | CEs|--|-{VRs}| |{VRs}-|--|CEs| +----+ +------+ +------+ +---+ \ / +---+ +---+ | P |....| P | +---+ +---+ Figure 1: Network Reference Model CE sites can be statically connected to the provider network via dedicated circuits, or can use dial-up links. Routing tables associated with each virtual router define the site-to-site reachability for each VPN. The internal backbone provider routers (P) are not VPN aware and do not keep VPN state. 3.1 Backbone Ould-Brahim, et al. March 2001 [Page 6] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 In general the backbone is a shared network infrastructure, which represents: (a) A layer-2 ATM or frame relay network. (b) An IP network. (c) An MPLS network. Not all VPNs existing on the same PE are necessarily connected to the same backbone. The same backbone can be built from multiple transport technologies. 4. Virtual Router Definition A virtual router (VR) is an emulation of a physical router at the software and hardware levels. Virtual routers have independent IP routing and forwarding tables and they are isolated from each other. This means that a VPN's addressing space can overlap with another VPN's address space. The addresses need only be unique within a VPN domain. A virtual router has two main functions: 1. Constructing routing tables describing the paths between VPN sites using any routing technologies (e.g., static, OSPF, RIP, or BGP). 2. Forwarding packets to the next hops within the VPN domain. From the VPN user point of view, a virtual router provides the same functionality as a physical router. Separate routing, and forwarding capabilities provide each VPN CE link with the appearance of a dedicated router that guarantees isolation from other VPN traffic while running on shared forwarding and transmission resources. Virtual routers belonging to the same VPN domain must have the same Virtual Private Network Identifier (VPNID). An example of VPNID format is described in [VPN-RFC2685]. To the CE access device, the virtual router appears as a neighbor router in the CE based network, to which it sends all traffic for non-local VPN destinations. Each CE access device must learn the set of destinations reachable through its connection to the virtual router; this may be as simple as a default route. Virtual routers participating in a single VPN domain are responsible for learning and disseminating VPN reachability information among themselves. A given virtual router holds the routes only for the specific VPNs configured for that VR. Any routing protocol can be used between the VRs and the CEs. 5. How VPNs are built and deployed using VRs? Two main VR deployment scenarios can be used for building virtual private networks: - VR to VR connectivity over a layer 2 connections. - Aggregating multiple virtual routers over a single virtual router. Ould-Brahim, et al. March 2001 [Page 7] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 The above VR deployment scenarios can coexist on a single PE and they are not mutually exclusive. 5.1 VR to VR Connectivity over Layer 2 Connections As illustrated in figure 2, virtual routers can be deployed over direct layer-2 frame relay or ATM connections or other layer-2 transport technology. PE PE +---------------+ +---------------+ +-----+ | | | | +-----+ |VPN-A| | +----+ Layer-2 connections +----+ | |VPN-A| |sites| | |VR-A|<---------------------------->|VR-A| | |sites| +-----+ | +----+ | -------- | +----+ | +-----+ | |-( Layer-2)-| | +-----+ | +----+ | (Backbone) | +----+ | +-----+ |VPN-B|-|-|VR-B| | -------- | |VR-B|-|-|VPN-B| |sites| | +----+<--------------------|------->+----+ | |sites| +-----+ | | | | +-----+ +---------------+ +---------------+ Figure 2: VR to VR connectivity over a layer-2 backbone This type of VR deployment allows direct quality of service engineering per VPN connection basis. The connections can be statically configured or dynamically established. 5.2 Virtual Router Backbone Aggregation Another typical VPN configuration consists of connecting multiple virtual routers to the backbone through the use of a single virtual router (figure 3). For easy reference in the following sections let's call this single virtual router "the backbone virtual router" or "the backbone VR". The backbone virtual router is not functionally different than other virtual routers. It is only a virtual router that is configured and deployed in a special configuration. Ould-Brahim, et al. March 2001 [Page 8] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 PE PE +---------------+ +---------------+ +-----+ | | | | +-----+ |VPN-A| | +----+ MPLS/IP based Tunnels +----+ | |VPN-A| |sites|-|-|VR-A|\.......|<---------->|........|VR-A|-|-|sites| +-----+ | +----+ +----+ --------- | +----+/+----+ | +-----+ | |VR-1|-|-(IP/MPLS )-|-|VR-2| | +-----+ | +----+/+----+ |(Backbones) | +----+\+----+ | +-----+ |VPN-B|-|-|VR-B| | --------- | |VR-B|-|-|VPN-B| |sites| | +----+........|<---------->|........+----+ | |sites| +-----+ | MPLS/IP based Tunnels | +-----+ | | | | +---------------+ +---------------+ Figure 3: VR-1 and VR-2 used as backbone VRs The backbone virtual router connects each PE to a shared backbone infrastructure. Backbone virtual routers can be deployed over ATM, FR, IP, or MPLS networks. Since the backbone VR allows the aggregation of VPN VRs, backbone configuration remains unaffected as new VPN sites are added. The relationship between the VRs and the backbone VR is an overlay relationship. 5.2.1 Tunneling VPN data and routing information is tunneled through the use of IP or MPLS based tunnels (e.g., IPSec, GRE, IP in IP, MPLS). Depending on the tunnel technology used, the tunnels can be statically configured or dynamically established. The tunnel appears to VRs as a point-to-point link. Traffic sent through the tunnel, and forwarded by the backbone VR is opaque to the underlying backbone technology used. A tunnel can be established per VPN or shared among many VPNs (VRs). The tunnel can originate from the backbone virtual router or from the VRs. The backbone VR makes it appear as if each VR within a VPN is directly connected (full and partial mesh configurations supported). Each VR within the VPN exchanges routing information directly with the other VRs in the VPN. VPNs may use different type of tunnels for inter-VR connectivity. Indeed, Two sites may use MPLS as their tunnel technology of choice. Other sites (which transit through not fully secured domains) may choose to use IPSec. 5.2.1.1 MPLS Tunnels MPLS tunneling can be used in different forwarding scenarios. Two labels hierarchy can be used. One simple forwarding scenario is the inner label identifies the VR intended to receive the private packet Ould-Brahim, et al. March 2001 [Page 9] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 (to be forwarded to the CE). Another forwarding scenario is to distribute the inner label per VPN basis across the tunnel. In this case the label distribution process can be achieved using BGP or existing label distribution protocol per VPN basis. The inner label relates to the private VPN prefix. The label and reachability distribution is done through the tunnels. On the egress side traffic will be directed to the egress interface by looking up the inner label. 5.2.1.2 IPSec Tunnels IPSec is needed when there is a requirement for strong encryption or strong authentication. It also supports multiplexing and a signalling protocol - IKE. IPSec tunnels can be established between two VPNs across the backbone (originating from the backbone VRs). 5.2.2 Routing The backbone VR exchanges routing information with other backbone entities (P routers and possibly other backbone VRs). Virtual routers can run any routing protocol on their local VPN domain. Both static routes and dynamic routing protocols such as RIP, OSPF, and BGP-4 can be used. VPN sites exchange routing information through the tunnels over the backbone. If a backdoor link is used between private CE based network running any IGP, then by adjusting the backdoor link costs appropriately, the backbone link can be favored for forwarding VPN traffic. By lowering the weight, the backdoor link can be used as a backup link in case the backbone path fails. 5.2.3 Relationship between the VRs and the Backbone VR The routing domain of a set of VRs participating in a single VPN has no relation to the routing domain of the backbone VR. The backbone VR is not necessarily aware of the routing instances running on each private virtual router. However, because the backbone VR is also a virtual router, it can build routing relationships with other VRs if needed. 5.2.4 Multiple Backbones connected to a single PE Figure 4 illustrates an example where multiple backbones are connected to the same PE. This type of configuration can be used when the PE is connected to multiple service provider backbones, or when the service provider offers different VPN services for different type of backbones. Ould-Brahim, et al. March 2001 [Page 10] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 PE PE +---------------+ +---------------+ +-----+ | | | | +-----+ |VPN-A| | +----+ | | +----+ | |VPN-A| |sites| | |VR-A|\ | | |VR-A| | |sites| +-----+ | +----+ +----+ | --------- | +----+/+----+ | +-----+ | |VR-1|-|-(Backbones)|-|VR-2| | +-----+ | +----+/+----+ | ( 1 )| +----+\+----+ | |VPN-B|-|-|VR-B| | --------- | |VR-B|-|-|VPN-B| |sites| | +----+ | | +----+ | |sites| +-----+ | | | | +-----+ | | | | +-----+ | | | | +-----+ |VPN-C| | +----+ | | +----+ | |VPN-C| |sites|-|-|VR C| | | |VR-C|-|-|sites| +-----+ | +----+\+----+ | -------- | +----+/+----+ | +-----+ | |VR-3|-|-(Backbone)-|-|VR-4| | +-----+ | +----+/+----+ | ( 2 & 3 ) | +----+\+----+ | +-----+ |VPN-D|-|-|VR-D| | -------- | |VR-D|-|-|VPN-D| |sites| | +----+ | | +----+ | |sites| +-----+ | | | | +-----+ +---------------+ +---------------+ Figure 4: Multiple Backbones connected to a single PE 6. VPN Auto-Discovery The virtual router approach explicitly separates the mechanisms used for distributing reachability information from mechanisms used for distributing VPN topology and membership information. VPN membership information refers to the set of PEs that have customers in a particular VPN. VPN topology represents the set of PEs and their interconnectivity within the VPN. The topology can be a full-mesh of PEs, a hub and spoke, or anything in between. Dynamic topology can also be handled due to on-demand VPN customers. VPN discovery can be achieved through different mechanisms, for example: - Directory server approach, which VRs query a server to determine their neighbors. - Explicit configuration via a management platform. - Piggybacking VPN membership and topology information using existing routing protocols (e.g., BGP) [VPN-BGP]. The above mechanisms can be combined on a single PE. As an example, for some VPNs topology discovery is done only through a management platform. For others, dynamic topology discovery is achieved using existing routing protocol. Ould-Brahim, et al. March 2001 [Page 11] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 In this document it is assumed that BGP is used as the mechanism for achieving auto-discovery of VPN members. As described in [VPN-BGP], VR addresses are exchanged, along with the information needed to enable the PEs to determine which VRs are in the same VPN ("membership"), and which of those VRs are to have VPN connectivity ("topology"). Once the VRs are reachable through the tunnels, routes ("reachability") are then exchanged by running existing routing protocol per VPN basis (across the tunnels). It is important to note that, for the VR architecture, the auto- discovery mechanism is only used to automatically exchange control VPN information between VRs. It is not intended for piggybacking vpn private reachability information onto the backbone routing instance. 7. VRs and Extranets Extranets are commonly used to refer to a scenario whereby two or more companies have network access to a limited amount of each other's corporate data. An important feature of extranets is the control of who can access what data, and this is essentially a policy decision. Policy decisions are enforced at the interconnection points between different domains [VPN-RFC2764]. The enforcement may be done via a firewall, router with access list functionality, or any device capable of applying policy decision to transit traffic. In the VR architecture, policy can be enforced between two VPNs, or between a VPN and the Internet, in exactly the same manner as is done today without VPNs. For example, two VRs (VPNs) could be interconnected, which each VR locally imposing its own policy controls, via a firewall, on all traffic that enters its VPN from the outside (whether from another VR or from the Internet). Combining firewalls and exchanging private routes between VRs (members of different VPNs) provide a flexible mechanism to build different flavors of extranets. 8. VPNs across Domains It is possible that a VPN may cross multiple domains administered by different service providers. In the VR model, tunnels are used to provide intra-VR connectivity across the backbones. The main requirement on the service provider in order to achieve end-to-end across domains VPN connectivity is the ability for both domains to support a common tunnel technology to be used. Once the tunnel is established, private data (e.g., routing information, and private customer data) can flow from one domain to the other with the same level of security as provided in a single service provider network. Another possible scenario is to use two virtual routers configured on each PE at the interconnection point. Each VR will use policy decisions and firewalling to control VPN traffic transiting from one domain to the other. Ould-Brahim, et al. March 2001 [Page 12] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 The ability to use the standard VPN-ID format allows also unambiguous VPN identification across domains. 9. Internet Access The same link attaching to the VR can be used to provide the internet access to the VPN sites. The VR operations are decoupled from the mechanisms used by the customer sites to access the internet. One way of providing VPN internet access is to have the PE/backbone- VR steering private traffic to the VR, and internet to normal backbone/internet forwarding table. PE/backbone VR can hold the internet routes (not necessarily the VRs). Firewalls need to be used to secure the access (with the ability to use NAT). Other options are also valid. One may want to have a particular VR handling internet access only (rather than going to the backbone VR), or a default route to the internet gateway can be used. 10. Carrier's Carriers Case It is possible that a VPN service is also a network of a service provider offering VPN services. Different options can be used to implement the VPN hierarchy. Either tunnels are built from the VPN edges to the CEs, and the VRs are transparently providing VPN service to the remote CEs. This can be useful in the case where the CEs are themselves VRs and the service provider is also outsourcing the management of his customer VPN services. Another case is the remote VPN services are completely transparent to the VRs (on the PEs). This is the default case. It is up to the VPN network to distribute VPN reachability across the CEs. Another option is for the VPN service to implement the VR architecture. In this option, the VPN Backbone VRs appear as CEs to the VRs configured on the PEs. 11. Operations and Management One of the greatest strengths of the VR approach to VPN creation is that all the existing tools for operating, managing and debugging IP networks can continue to be used without modification. All the standard MIBs, such as the forwarding/route table and interface MIBs are available. In case of PE failure (e.g. migration, upgrades, etc.), the service provider may want to control and decide what VPN services gets reestablished first. This particular point is important when a large number of VPNs is supported on the PE where each VPN service has different service availability requirements. Since each VR operates as an independent router, it is possible for the management of the VRs to be outsourced. VPN customers may choose to configure (or perhaps only to monitor) the VRs that make up their VPN. It is also possible that the backbone VRs could be Ould-Brahim, et al. March 2001 [Page 13] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 managed by a separate entity. Each VR operates independently, and can be individually reconfigured without effecting other VRs on the same PE. In some implementations, it may even be possible for a VR to be "rebooted" by a customer without affecting other VRs. It is not required for a given VR implementation to support all management capabilities described in this section. 11.1 Backbone Migration One benefit in using multiple backbone virtual routers is the ability for the backbone network administrator to migrate its backbone from one core technology to another with minimal disruption to VPN services. Indeed a VPN configuration change or a VPN-software upgrade is totally transparent to the backbone protocol and policies (this is due to decoupling the VPN routing protocol from the provider backbone routing protocol). 11.2 Troubleshooting The service provider or the VPN customer can use all existing troubleshooting tools per VPN basis (e.g. ping and traceroute). As an example a VPN customer can telnet to its own VR and performs some troubleshooting operations. In this particular case, the service provider can configure for each VPN customer restricted privileges over the virtual router associated with the customer VPN network. However, backbone topology information is completely hidden to the VPN VR, and therefore to the service provider customer. 12. Quality of Service This architecture 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. 13. Scalability Only the PEs are handling the VPN type information. The internal backbone routers (the P routers) are not VPN aware. Furthermore, virtual routers allow multiple privates CE based networks to connect to a single PE. One advantage of the ability to contain the VPN address space and VPN routing and forwarding capabilities within the virtual router entity is the possibility to distribute PE system resources per VPN basis. Indeed, as an example, different scheduling mechanisms can be used for processing each VPN activity within the PE. This type of per VPN resource management contributes in establishing a wide range of priority schemes among VPNs within the PE. Ould-Brahim, et al. March 2001 [Page 14] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 14. Security Considerations Different levels of data, routing and configuration security can be implemented. Any existing security related mechanisms supported by existing routing protocols (e.g. authentication) can be used unmodified in the VR architecture. If IPSec tunneling is used as the tunneling protocol, then both the control and data traffic that travels over the tunnel can be secured; so that routing specific security enhancements are not needed. Any private routing, forwarding and addressing manipulation are done within the virtual router context. Direct layer-2 connections (ATM, FR), or specific tunneling mechanisms can also provide different levels of data security. 15. References [GRE-RFC1701] Hanks, S., Li, T., Farinacci, D. and P. Traina, "Generic Routing Encapsulation (GRE)", RFC 1701, October 1994. [CR-LDP] Jamoussi, B., et al, "Constraint-based LSP Setup using LDP", Work in Progress. [RFC-2003] Perkins, C., "IP Encapsulation within IP", RFC 2003, October 1996. [RFC-2026] Bradner, S., "The Internet Standards Process -- Revision 3", RFC 2026, October 1996. [RFC-2401] Kent S., Atkinson R., "Security Architecture for the Internet Protocol", RFC2401, November 1998. [RFC-2411] Thayer, R., et al, "IP Security Document Roadmap", RFC 2411, November 1998. [RFC-2661] Townsley, W., et al, "Layer Two Tunneling Protocol L2TP", RFC2661, August 1999. [RFC-2685] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. [VPN-CORE] Muthukrishnan, K., Malis, A., "Core MPLS IP VPN Architecture", Work in Progress [VPN-BGP] Ould-Brahim, H., et al., "Using BGP as an Auto-Discovery Mechanism for Network-based VPNs", work in progress, November 2000. [VPN-INW] Sumimoto, J., et al, "MPLS VPN Interworking", Work in Progress. Ould-Brahim, et al. March 2001 [Page 15] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 [VPN-ITU] "Draft Recommendation Y.IPVPN", Study Group 13, Q20/13, May 2000. [VPN-RFC2547bis] Rosen E., et al, "BGP/MPLS VPNs", work in progress. [VPN-RFC2685] Fox B., et al, "Virtual Private Networks Identifier", RFC 2685, September 1999. [VPN-RFC2764] Gleeson, B., et al., "A Framework for IP Based Virtual Private Networks", RFC 2764, February 2000. 16. Acknowledgments The authors would like to acknowledge the following individuals for their helpful comments and suggestions: Bilel Jamoussi, David Hudson, David Drynan, Ru Wadasinghe, Scott Larrigan, Peter Ashwood- Smith, Martin Pepin, Ahmad Khalid, Don Fedyk, Keereti Melkote, Ron Bonica, Jerry Sydir, and Mark Duffy. 17. Author's Addresses Hamid Ould-Brahim Bryan Gleeson Nortel Networks Nortel Networks P O Box 3511 Station C 2305 Mission College Blvd Ottawa, ON K1Y 4H7 Santa Clara CA 95054 Canada USA Phone: +1 (613) 765 3418 Phone: +1 (408) 565 2625 Email: hbrahim@nortelnetworks.com Email:bgleeson@shastanets.com Gregory Wright Timon Sloane Nortel Networks Webstacks P O Box 3511 Station C 444 Oakmead Parkway Ottawa, ON K1Y 4H7 Sunnyvale, CA 94085 Canada USA Phone: +1 (613) 765 7912 Phone: +1 408-524-8484 Email: gwright@nortelnetworks.com Email:timon@webstacksinc.com Rainer Bach Rick Bubenik, T-Data SAVVIS Communications Hans-Guenther-Sohl-Strasse7 717 Office Parkway 40235, Duesseldorf St. Louis, Mo. 63141 Germany USA Phone: 49 211 694 2420 Phone: +1 (314) 468-7021 Ould-Brahim, et al. March 2001 [Page 16] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 Email: Rainer.Bach@telekom.de rickb@savvis.net Abraham Young Jieyun Jessica Yu HUAWEI Technologies Co., LTD. Cosine Communications Kefa Road 1200 Bridge Parkway Science-Based Industrial Park Redwood City CA 94065 Nanshan District, Shenzhen 518057 CA 94065 China USA Phone: +86-755-6543662 Phone: +1 (650) 628-4881 Email: abyoung@huawei.com.cn Email: jyy@cosinecom.com Chandru Sargor Cosine Communications 1200 Bridge Parkway Redwood City CA 94065 USA Phone: +1 (650) 637-2416 Email: Chandramouli.Sargor@cosinecom.com Luyuan Fang AT&T 200 Laurel Avenue Middletown, NJ 07748 Phone: +1 (732) 420-1921 Email: Luyuanfang@att.com Ould-Brahim, et al. March 2001 [Page 17] Internet-Draft draft-ouldbrahim-vpn-vr-03.txt September 2001 Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. 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