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The IP virtual private network (VPN) feature for Multiprotocol Label Switching (MPLS) allows a Cisco IOS network to deploy scalable IPv4 Layer 3 VPN backbone services. An IP VPN is the foundation companies use for deploying or administering value-added services including applications and data hosting network commerce, and telephony services to business customers.
In private local area networks (LANs), IP-based intranets have fundamentally changed the way companies conduct their business. Companies are moving their business applications to their intranets to extend over a wide area network (WAN). Companies are also embracing the needs of their customers, suppliers, and partners by using extranets (an intranet that encompasses multiple businesses). With extranets, companies reduce business process costs by facilitating supply-chain automation, electronic data interchange (EDI), and other forms of network commerce. To take advantage of this business opportunity, service providers must have an IP VPN infrastructure that delivers private network services to businesses over a public infrastructure.
The following table lists the old Tag Switching terms and the new MPLS terms found in this document.
| Old Designation | New Designation |
|---|---|
Tag Switching | MPLS, Multiprotocol Label Switching |
Tag (short for Tag Switching) | MPLS |
Tag (item or packet) | Label |
TDP (Tag Distribution Protocol) | LDP (Label Distribution Protocol) Note Cisco TDP and LDP (MPLS Label Distribution Protocol)) are nearly identical in function, but use incompatible message formats and some different procedures. Cisco will be changing from TDP to a fully compliant LDP. |
Tag Switched | Label Switched |
TFIB (Tag Forwarding Information Base) | LFIB (Label Forwarding Information Base) |
TSR (Tag Switching Router) | LSR (Label Switching Router) |
TSC (Tag Switch Controller) | LSC (Label Switch Controller) |
ATM-TSR | ATM-LSR (ATM Label Switch Router, for example, |
TVC (Tag VC, Tag Virtual Circuit) | LVC (Label VC, Label Virtual Circuit) |
TSP (Tag Switch Path) | LSP (Label Switch Path) |
XTagATM (extended Tag ATM port) | XmplsATM (extended MPLS ATM port) |
To effectively implement an IP VPN in your facility, ensure your IP VPN meets the following basic requirements:
Privacy---All IP VPNs offer privacy over a shared (public) network infrastructure. Most companies use an encrypted tunnel. This is only one of several ways to provide network and data privacy.
Scalability---For proper service delivery, VPNs must scale to serve hundreds of thousands of sites and users. Besides being a managed service, VPNs are also a management tool for service providers to control access to services. One example is Closed User Groups for data and voice services.
Flexibility---IP VPNs must handle the any-to-any traffic patterns characteristic of corporate intranets and extranets, in which data no longer flows to and from a central location. VPNs must also have the inherent flexibility to add new sites quickly, connect users over different media, and meet the increasingly sophisticated transport and bandwidth requirements of new intranet applications.
Predictable Performance---Performance needs vary widely requiring different classes of service, but the common requirement is that the performance is predictable. Examples of the ranges of performance requirements include:
MPLS VPNs allow service providers to deploy scalable VPNs and build the foundation to deliver value-added services, including:
Connectionless Service---A significant technical advantage of MPLS VPNs is that they are connectionless. The Internet owes its success to its basic technology, TCP/IP. TCP/IP is built on packet-based, connectionless network paradigm. This means that no prior action is necessary to establish communication between hosts, making it easy for two parties to communicate. To establish privacy in a connectionless IP environment, current VPN solutions impose a connection-oriented, point-to-point overlay on the network. Even if it runs over a connectionless network, a VPN cannot take advantage of the ease of connectivity and multiple services available in connectionless networks. When you create a connectionless VPN, you do not need tunnels and encryption for network privacy, thus eliminating significant complexity.
Centralized Service---Building VPNs in Layer 3 allows delivery of targeted services to a group of users represented by a VPN. A VPN must give service providers more than a mechanism for privately connecting users to intranet services. It must also provide a way to flexibly deliver value-added services to targeted customers. Scalability is critical, because customers want to use services privately in their intranets and extranets. Because MPLS VPNs are seen as private intranets, you may use new IP services such as:
You can customize several combinations of specialized services for individual customers. For example, a service that combines IP multicast with a low-latency service class enables videoconferencing within an intranet.
Scalability---If you create a VPN using connection-oriented, point-to-point overlays, Frame Relay, or ATM virtual connections (VCs), the VPN's key deficiency is scalability. Specifically, connection-oriented VPNs without fully meshed connections between customer sites, are not optimal. MPLS-based VPNs instead use the peer model and Layer 3 connectionless architecture to leverage a highly scalable VPN solution. The peer model requires a customer site to only a peer with one provider edge (PE) router as opposed to all other CPE or customer edge (CE) routers that are members of the VPN. The connectionless architecture allows the creation of VPNs in Layer 3, eliminating the need for tunnels or VCs.
Other scalability issues of MPLS VPNs are due to the partitioning of VPN routes between PE routers and the further partitioning of VPN and IGP routes between PE routers and provider (P) routers in a core network.
This increases the scalability of the provider's core and ensures that no one device is a scalability bottleneck.
Security---MPLS VPNs offer the same level of security as connection-oriented VPNs. Packets from one VPN do not inadvertently go to another VPN. Security is provided
1. At the edge of a provider network, ensuring packets received from a customer are placed on the correct VPN.
2. At the backbone, VPN traffic is kept separate. Malicious spoofing (an attempt to gain access to a PE router) is nearly impossible because the packets received from customers are IP packets. These IP packets must be received on a particular interface or subinterface to be uniquely identified with a VPN label.
Easy to Create---To take full advantage of VPNs, it must be easy for customers to create new VPNs and user communities. Because MPLS VPNs are connectionless, no specific point-to-point connection maps or topologies are required. You can add sites to intranets and extranets and form closed user groups. When you manage VPNs in this manner, it enables membership of any given site in multiple VPNs, maximizing flexibility in building intranets and extranets.
Flexible Addressing---To make a VPN service more accessible, customers of a service provider can design their own addressing plan, independent of addressing plans for other service provider customers. Many customers use private address spaces, as defined in RFC 1918, and do not want to invest the time and expense of converting to public IP addresses to enable intranet connectivity. MPLS VPNs allow customers to continue to use their present address spaces without network address translation (NAT) by providing a public and private view of the address. A NAT is required only if two VPNs with overlapping address spaces want to communicate. This enables customers to use their own unregistered private addresses, and communicate freely across a public IP network.
Integrated Class of Service (CoS) Support---CoS is an important requirement for many IP VPN customers. It provides the ability to address two fundamental VPN requirements:
1. Predictable performance and policy implementation
2. Support for multiple levels of service in a MPLS VPN
Network traffic is classified and labeled at the edge of the network before traffic is aggregated according to policies defined by subscribers and implemented by the provider and transported across the provider core. Traffic at the edge and core of the network can then be differentiated into different classes by drop probability or delay.
Straightforward Migration---For service providers to quickly deploy VPN services, use a straightforward migration path. MPLS VPNs are unique because you can be build them over multiple network architectures, including IP, ATM, Frame Relay, and hybrid networks.
Migration for the end customer is simplified because there is no requirement to support MPLS on the customer edge (CE) router and no modifications are required to a customer's intranet.
For a list of platforms supported by MPLS VPNs, refer to the section entitled Supported Platforms.
Figure 1 shows an example of a VPN with a service provider (P) backbone network, service provider edge routers (PE), and customer edge routers (CE).
A VPN contains customer devices attached to the CE routers. These customer devices use VPNs to exchange information between devices. Only the PE routers are aware of the VPNs.
Figure 2 shows five customer sites communicating within three VPNs. The VPNs can communicate with the following sites:
Each VPN is associated with one or more VPN routing/forwarding instances (VRFs). A VRF defines the VPN membership of a customer site attached to a PE router. A VRF consists of an IP routing table, a derived Cisco Express Forwarding (CEF) table, a set of interfaces that use the forwarding table, and a set of rules and routing protocol parameters that control the information that is included into the routing table.
A one-to-one relationship does not necessarily exist between customer sites and VPNs. A given site can be a member of multiple VPNs, as shown in Figure 2. However, a site can only associate with one (and only one) VRF. A customer site's VRF contains all the routes available to the site from the VPNs of which it is a member.
Packet forwarding information is stored in the IP routing table and the CEF table for each VRF. A separate set of routing and CEF tables is maintained for each VRF. These tables prevent information from being forwarded outside a VPN, and also prevent packets that are outside a VPN from being forwarded to a router within the VPN.
The distribution of VPN routing information is controlled through the use of VPN route target communities, implemented by border gateway protocol (BGP) extended communities. Distribution of VPN routing information works as follows:
A service provider edge (PE) router can learn an IP prefix from a customer edge (CE) router
by static configuration, through a BGP session with the CE router, or through the routing information protocol (RIP) exchange with the CE router. The IP prefix is a member of the IPv4 address family. After it learns the IP prefix, the PE converts it into a VPN-IPv4 prefix by combining it with an 8-byte route distinguisher (RD). The generated prefix is a member of the VPN-IPv4 address family. It serves to uniquely identify the customer address, even if the customer site is using globally nonunique (unregistered private) IP addresses.
The route distinguisher used to generate the VPN-IPv4 prefix is specified by a configuration command associated with the VRF on the PE router.
BGP distributes reachability information for VPN-IPv4 prefixes for each VPN. BGP communication takes place at two levels: within IP domains, known as an autonomous systems (interior BGP or IBGP) and between autonomous systems (external BGP or EBGP). PE-PE or PE-RR (route reflector) sessions are IBGP sessions, and PE-CE sessions are EBGP sessions.
BGP propagates reachability information for VPN-IPv4 prefixes among PE routers by means of the BGP multiprotocol extensions (see RFC 2283, Multiprotocol Extensions for BGP-4) which define support for address families other than IPv4. It does this in a way that ensures the routes for a given VPN are learned only by other members of that VPN, enabling members of the VPN to communicate with each other.
Based on routing information stored in the VRF IP routing table and VRF CEF table, packets are forwarded to their destination using MPLS.
A PE router binds a label to each customer prefix learned from a CE router and includes the label in the network reachability information for the prefix that it advertises to other PE routers. When a PE router forwards a packet received from a CE router across the provider network it labels the packet with the label learned from the destination PE router. When the destination PE router receives the labeled packet it pops the label and uses it to direct the packet to the correct CE router. Label forwarding across the provider backbone, is based on either dynamic label switching or traffic engineered paths. A customer data packet carries two levels of labels when traversing the backbone:
1. Top label directs the packet to the correct PE router
2. Second label indicates how that PE router should forward the packet to the CE router
This section describes the benefits of VPNs in general and MPLS VPNs in particular.
IP VPNs are attractive because they:
1. Reduce the cost of connecting branch offices, telecommuters, and mobile users to a corporate intranet, which operate over the public infrastructure of the Internet
2. Are more cost-effective than private WANs constructed with leased lines
However, conventional VPNs do not scale well. They are based on creating and maintaining a full mesh of tunnels or permanent virtual circuits among all sites belonging to a particular VPN, using:
MPLS VPNs, which are created in Layer 3, are connectionless, and therefore substantially more scalable and easier to build and manage than conventional VPNs. In addition, you can add value-added services, such as application and data hosting, network commerce, and telephony services to a particular MPLS VPN because the service provider's backbone recognizes each MPLS VPN as a separate, connectionless IP network.
VPNs may be used with the Class of Service (CoS) feature for MPLS.
The following is a list of router platforms supported at the provider core.
The following is a list of router platforms supported at the provider edge.
No new or modified MIBs are supported by this feature.
No new or modified standards are supported by this feature.
Your network must be running the following Cisco IOS services before you configure VPN operation:
Perform the following tasks to configure and verify VPNs:
To define VPN routing instances, perform the following steps on the PE router:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)#ip vrf vrf-name | Enter VRF configuration mode and define the VPN routing instance by assigning a VRF name. | ||
| Router(config-vrf)#rd route-distinguisher | Create routing and forwarding tables. | ||
| Router(config-vrf)#route-target {import | export |
both} route-target-ext-community
| Create a list of import and/or export route target communities for the specified VRF. | ||
| Router(config-vrf)#import map route-map | (Optional) Associate the specified route map with the VRF. | ||
| Router(config-if)# | Associate a VRF with an interface or subinterface. |
To configure BGP PE to PE routing sessions in a provider network, perform the following steps on the PE routers:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)#router bgp autonomous-system | Configures the IBGP routing process with the autonomous system number passed along to other IBGP routers. | ||
| Router(config-router)#neighbor {ip-address |
peer-group-name} remote-as number
| Specifies a neighbor's IP address or IBGP peer group identifying it to the local autonomous system. | ||
| Router(config-router)#neighbor ip-address activate | Activates the advertisement of the IPv4 address family. |
To configure BGP PE to CE routing sessions perform the following steps on the PE router:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)#router bgp autonomous-system | Configures a EBGP routing process with the autonomous system number passed along to other EBGP routers. | ||
| Router(config-router)#neighbor {ip-address |
peer-group-name} remote-as number
| Specifies a neighbor's IP address or EBGP peer group identifying it to the local autonomous system. | ||
| Router(config-router)#neighbor ip-address activate | Activates the advertisement of the IPv4 address family. |
To configure RIP PE to CE routing sessions perform the following steps on the PE router:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)#router rip | Enables RIP. | ||
| Router(config-router)#address-family ipv4 [unicast] vrf vrf-name | Note The default is Off for auto-summary and synchronization in the VRF address-family submode. | ||
| Router(config-router)#network prefix | Enables RIP on the PE to CE link. |
To configure static route PE to CE routing sessions perform the following steps on the PE router:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router(config)#ip route vrf vrf-name | Defines static route parameters for every PE to CE session. | ||
| Router(config-router)#address-family ipv4 [unicast] vrf vrf-name | Defines static route parameters for every BGP PE to CE routing session. Note The default is Off for auto-summary and synchronization in the VRF address-family submode. | ||
| Router(config-router)#redistribute static | Redistributes VRF static routes into the VRF BGP table. | ||
| Router(config-router)#redistribute static connected | Redistributes directly connected networks into the VRF BGP table. |
To verify VPN operation, perform the following steps:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| Router#show ip vrf | Displays the set of defined VRFs and interfaces. | ||
| Router#show ip vrf [{brief | detail | interfaces}]
vrf-name
| Displays information about defined VRFs and associated interfaces. | ||
| Router# | Displays the IP routing table for a VRF. | ||
| Router#show ip protocols vrf vrf-name | Displays the routing protocol information for a VRF. | ||
| Router#show ip cef vrf vrf-name | Displays the CEF forwarding table associated with a VRF. | ||
| Router#show ip interface interface-number | Displays the VRF table associated with an interface. | ||
| Router#show ip bgp vpnv4 all [tags] | Displays information about all BGPs. | ||
| Router#show tag-switching forwarding vrf vrf-name [prefix mask/length][detail] | Displays label forwarding entries that correspond to VRFroutes advertised by this router. |
This section provides a sample configuration file from a PE router.
ip cef distributed ! CEF switching is pre-requisite for label Switching frame-relay switching ! ip vrf vrf1 ! Define VPN Routing instance vrf1 rd 100:1 route-target both 100:1 ! Configure import and export route-targets for vrf1 ! ip vrf vrf2 ! Define VPN Routing instance vrf2 rd 100:2 route-target both 100:2 ! Configure import and export route-targets for vrf2 route-target import 100:1 ! Configure an additional import route-target for vrf2 import map vrf2_import ! Configure import route-map for vrf2 ! interface lo0 ip address 10.13.0.13 255.255.255.255 ! interface atm9/0/0 ! Backbone link to another Provider router ! interface atm9/0/0.1 tag-switching ip unnumbered loopback0
no ip directed-broadcast
tag-switching atm vpi 2-5 tag-switching ip interface atm5/0
no ip address
no ip directed-broadcast
atm clock INTERNAL
no atm ilmi-keepalive interface Ethernet1/0
ip address 3.3.3.5 255.255.0.0
no ip directed-broadcast no ip mroute-cache no keepalive interface Ethernet5/0/1 ! Set up Ethernet interface as VRF link to a CE router ip vrf forwarding vrf1 ip address 10.20.0.13 255.255.255.0 ! interface hssi 10/1/0 hssi internal-clock encaps fr frame-relay intf-type dce frame-relay lmi-type ansi ! interface hssi 10/1/0.16 point-to-point ip vrf forwarding vrf2 ip address 10.20.1.13 255.255.255.0 frame-relay interface-dlci 16 ! Set up Frame Relay PVC subinterface as link to another ! ! CE router router bgp 1 ! Configure BGP sessions no synchronization no bgp default ipv4-activate ! Deactivate default IPv4 advertisements neighbor 10.15.0.15 remote-as 1 ! Define IBGP session with another PE neighbor 10.15.0.15 update-source lo0 ! address-family vpnv4 unicast ! Activate PE exchange of VPNv4 NLRI neighbor 10.15.0.15 activate exit-address-family ! address-family ipv4 unicast vrf vrf1 ! Define BGP PE-CE session for vrf1 redistribute static
redistribute connected neighbor 10.20.0.60 remote-as 65535 neighbor 10.20.0.60 activate no auto-summary exit-address-family ! address-family ipv4 unicast vrf vrf2 ! Define BGP PE-CE session for vrf2 redistribute static
redistribute connected neighbor 10.20.1.11 remote-as 65535 neighbor 10.20.1.11 update-source h10/1/0.16 neighbor 10.20.1.11 activate no auto-summary exit-address-family ! ! Define a VRF static route ip route vrf vrf1 12.0.0.0 255.0.0.0 e5/0/1 10.20.0.60 ! route-map vrf2_import permit 10 ! Define import route-map for vrf2. ...
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command references.
In Cisco IOS Release 12.0(1)T or later, you can search and filter the output for show and more commands. This functionality is useful when you need to sort through large amounts of output, or if you want to exclude output that you do not need to see.
To use this functionality, enter a show or more command followed by the "pipe" character (|), one of the keywords begin, include, or exclude, and an expression that you want to search or filter on:
command | {begin | include | exclude} regular-expression
Following is an example of the show atm vc command in which you want the command output to begin with the first line where the expression "PeakRate" appears:
show atm vc | begin PeakRate
For more information on the search and filter functionality, refer to the Cisco IOS Release 12.0(1)T feature module titled CLI String Search.
boldface font | Commands and keywords are in boldface. |
italic font | Arguments for which you supply values are in italics. In contexts that do not allow italics, arguments are enclosed in angle |
[ ] | Elements in square brackets are optional. |
{ x | y | z } | Required alternative keywords are grouped in braces and separated by vertical bars. |
[ x | y | z ] | Optional alternative keywords are grouped in brackets and separated by vertical bars. |
To enter the address family submode for configuring routing protocols, such as BGP, RIP and static routing, use the address-family global configuration command. To disable the address family submode for configuring routing protocols, use the no form of this command.
ipv4 | Configures sessions that carry standard IPv4 address prefixes. |
vpnv4 | Configures sessions that carry customer VPN-IPv4 prefixes, each of which has been made globally unique by adding an 8-byte route distinguisher. |
unicast | (Optional) Specifies unicast prefixes. |
vrf vrf-name | Specifies the name of a VPN routing/forwarding instance (VRF) to associate with submode commands. |
Routing information for address family IPv4 is advertised by default when you configure a BGP session using the neighbor...remote-as command unless you execute the no bgp default ipv4-activate command.
Router configuration
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
Using the address-family command puts you in address family configuration submode (prompt: (config-router-af)# ). Within this submode, you can configure address-family specific parameters for routing protocols, such as BGP, that can accommodate multiple Layer 3 address families.
To leave address family configuration submode and return to router configuration mode, type exit-address-family, or simply exit.
The address-family command in the following example puts the router into address family configuration submode for the VPNv4 address family. Within the submode, you can configure advertisement of NLRI for the VPNv4 address family using neighbor activate and other related commands:
(config)# router bgp 100
(config-router)# address-family vpnv4
(config-router-af)#
The command in the following example puts the router into address family configuration submode for the IPv4 address family. Use this form of the command, which specifies a VRF, only to configure routing exchanges between PE and CE devices. This address-family command causes subsequent commands entered in the submode to be executed in the context of VRF vrf2. Within the submode, you can use neighbor activate and other related commands to accomplish the following:
Entered the address family submode as follows:
(config)# router bgp 100
(config-router)# address-family ipv4 unicast vrf vrf2
(config-router-af)#
| Command | Description |
Exits address family submode. | |
Exchanges an address with a neighboring router. |
To remove routes from the VRF routing table, use the clear ip route vrf EXEC command.
clear ip route vrf vrf-name {* | network [mask]}
vrf-name | Name of the VPN routing/forwarding instance (VRF) for the static route. |
* | Deletes all routes for a given VRF. |
network | Destination to be removed, in dotted-decimal format. |
mask | (Optional) Mask for the specified network destination, in dotted-decimal format. |
No default behavior or values.
EXEC
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced |
Use this command to clear routes from the routing table. Use the asterisk (*) to delete all routes from the forwarding table for a specified VRF, or enter the address and mask of a particular network to delete the route to that network.
The following command removes the route to the network 10.13.0.0 in the vpn1 routing table:
Router#clear ip route vrf vpn1 10.13.0.0
| Command | Description |
Displays the IP routing table associated with a VRF. |
To exit from the address family submode, use the exit-address-family address family submode command.
exit-address-familyThis command has no arguments or keywords.
No default behavior or values.
Address family submode
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
This command can be abbreviated to exit.
The following example shows how to exit the address-family command mode:
(config-router-af)#exit-address-family
| Command | Description |
Enters the address family submode used to configure routing protocols. |
To configure an import route map for a VRF, use the import VRF submode command.
import map route-map
route-map | Specifies the route map to be used as an import route map for the VRF. |
There is no default. A VRF has no import route map unless one is configured using the import map command.
VRF submode
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
Use an import route map when an application requires finer control over the routes imported into a VRF than provided by the import and export extended communities configured for the importing and exporting VRF.
The import-map command associates a route map with the specified VRF. You can filter routes that are eligible for import into a VRF, based on the route target extended community attributes of the route, through the use of a route map. The route map might deny access to selected routes from a community that is on the import list.
The following example shows how to configure an import route map for a VRF:
(config)#ip vrf vrf_blue (config-vrf)#import map blue_import_map
| Command | Description |
Enters VRF configuration mode. | |
Configures import and export extended community attributes for the VRF. | |
Displays information about a VRF or all VRFs. |
To establish static routes for a VRF, use the ip route vrf global configuration command. To disable static routes, use the no form of this command.
ip route vrf vrf-name prefix mask [next-hop-address] [interface {interface-number}]vrf-name | Name of the VPN routing/forwarding instance (VRF) for the static route. |
IP route prefix for the destination, in dotted-decimal format. | |
Prefix mask for the destination, in dotted-decimal format. | |
(Optional) IP address of the next hop (the forwarding router that can be used to reach that network). | |
interface | (Optional) Type of network interface to use: ATM, Ethernet, loopback, POS (packet over SONET), or null. |
interface-number | Number identifying the network interface to use. |
Specifies that the given next hop address is in the non-VRF routing table. | |
distance | (Optional) An administrative distance for this route. |
permanent | (Optional) Specifies that this route will not be removed, even if the interface shuts down. |
tag tag | (Optional) Label value that can be used for controlling redistribution of routes through route maps. |
No default behavior or values.
Global configuration
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
Use a static route when the Cisco IOS software cannot dynamically build a route to the destination.
If you specify an administrative distance when you set up a route, you are flagging a static route that can be overridden by dynamic information. For example, IGRP-derived routes have a default administrative distance of 100. To set a static route to be overridden by an IGRP dynamic route, specify an administrative distance greater than 100. Static routes each have a default administrative distance of 1.
Static routes that point to an interface are advertised through RIP, IGRP, and other dynamic routing protocols, regardless of whether the routes are redistributed into those routing protocols. That is, static routes configured by specifying an interface lose their static nature when installed into the routing table.
However, if you define a static route to an interface not defined in a network command, no dynamic routing protocols advertise the route unless a redistribute static command is specified for these protocols.
The following command reroutes packets addressed to network 137.23.0.0 in VRF vpn3 to router 131.108.6.6:
(config)#ip route vrf vpn3 137.23.0.0 255.255.0.0 131.108.6.6
| Command | Description |
Displays the IP routing table associated with a VRF. |
To associate a VRF with an interface or subinterface, use the ip vrf forwarding interface configuration command. To disassociate a VRF, use the no form of this command.
ip vrf forwarding vrf-name
vrf-name | Name assigned to a VRF. |
The default for an interface is the global routing table.
Global configuration
Interface configuration
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
Use this command to associate an interface with a VRF. Executing this command on an interface removes the IP address. The IP address should be reconfigured.
The following example shows how to link a VRF to ATM interface 0/0:
(config)#interface atm0/0 (config-if)#ip vrf forwarding vpn1
| Command | Description |
Defines a VRF. | |
Establishes static routes for a VRF. |
To configure a VRF routing table, use the ip vrf global configuration command. To remove a VRF routing table, use the no form of this command.
ip vrf vrf-namevrf-name | Name assigned to a VRF. |
No VRFs are defined. No import or export lists are associated with a VRF. No route maps are associated with a VRF.
Router configuration
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
The ip vrf vrf-name command creates a VRF routing table and a CEF (forwarding) table, both named vrf-name. Associated with these tables is the default route distinguisher value route-distinguisher.
The following example imports a route map to a VRF:
(Router-config)#ip vrf vpn1
(config-vrf)#rd 100:2 route-target both 100:2 route-target import 100:1
| Command | Description |
Associates a VRF with an interface or subinterface. |
To enable the exchange of information with a BGP neighboring router, use the neighbor activate router configuration command. To disable the exchange of an address with a neighboring router, use the no form of this command.
neighbor {ip-address | peer-group-name} activate
ip-address | IP address of the neighboring router. |
peer-group-name | Name of BGP peer group. |
For all other address families, address exchange is disabled by default. You can explicitly activate the default command using the appropriate address family submode.
Router configuration
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
Use this command to enable or disable the exchange of addresses with a neighboring router.
In the following example, a BGP router activates the exchange of a customer's IP address 10.15.0.15 to a neighboring router.
router bgp 100 neighbor 10.15.0.15 remote-as 100 neighbor 10.15.0.15 update-source loopback0 address-family vpnv4 unicast neighbor 10.15.0.15 activate exit-address-family
| Command | Description |
Enters the address family submode. | |
exit-address-family | Exits the address family submode. |
To create routing and forwarding tables for a VRF, use the rd VRF submode command.
rd route-distinguisher
route-distinguisher | Adds an 8-byte value to an IPv4 prefix to create a VPN IPv4 prefix. |
There is no default. An RD must be configured for a VRF to be functional.
VRF submode
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
A route distinguisher (RD) creates routing and forwarding tables and specifies the default route-distinguisher for a VPN. The RD is added to the beginning of the customer's IPv4 prefixes to change them into globally unique VPN-IPv4 prefixes.
You can enter an RD in either of these formats:
16-bit AS number: your 32-bit number
For example, 101:3
32-bit IP address: your 16-bit number
For example, 192.168.122.15:1
The following example configures a default RD for two VRFs. It illustrates the use of both AS-relative and IP address-relative RDs:
(config)#ip vrf vrf_blue (config-vrf)#rd 100:3 (config-vrf)#ip vrf vrf_red (config-vrf)#rd 173.13.0.12:200
| Command | Description |
Enters VRF configuration mode. | |
Displays information about a VRF. |
To create a route-target extended community for a VRF, use the route-target VRF submode command. To disable the configuration of a route-target community option, use the no form of this command.
route-target {import | export | both} route-target-ext-community
import | Imports routing information from the target VPN extended community. |
export | Exports routing information to the target VPN extended community. |
both | Imports both import and export routing information to the target VPN extended community. |
route-target-ext-community | Adds the route-target extended community attributes to the VRF's list of import, export, or both (import and export) route-target extended communities. |
There are not defaults. A VRF has no route-target extended community attributes associated with it until specified by the route-target command.
VRF submode
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
The route-target command creates lists of import and export route target extended communities for the specified VRF. Execute the command one time for each target community. Learned routes that carry a specific route target extended community are imported into all VRFs configured with that extended community as an import route target. Routes learned from a VRF site (for example, by BGP, RIP, or static route configuration) contain export route targets for extended communities configured for the VRF added as route attributes to control the VRFs into which the route is imported.
The route-target specifies a target VPN extended community. Like a route-distinguisher, an extended community is composed of either an autonomous system number and an arbitrary number, or an IP address and an arbitrary number. You can enter the numbers in either of these formats:
The following example shows how to configure route-target extended community attributes for a VRF. The result of the command sequence is that VRF vrf_blue has two export extended communities (1000:1 and 1000:2) and two import extended communities (1000:1 and 173.27.0.130:200).
(config)#ip vrf vrf_blue (config-vrf)#route-target both 1000:1 (config-vrf)#route-target export 1000:2 (config-vrf)#route-target import 173.27.0.130:200
| Command | Description |
ip vrf | Enters VRF configuration mode. |
import | Configures an import route map for the VRF. |
To display VPN address information from the BGP table, use the show ip bgp vpnv4 EXEC command.
show ip bgp vpnv4 {all | rd route-distinguisher | vrf vrf-name}all | Displays the complete VPNv4 database. |
rd route-distinguisher | |
vrf vrf-name | Displays NLRIs associated with the named VRF. |
ip-prefix/length | (Optional) IP prefix address (in dotted decimal format) and length of mask (0 to 32). |
longer-prefixes | (Optional) Displays the entry, if any, that exactly matches the specified prefix parameter, as well as all entries that match the prefix in a "longest-match" sense. That is, prefixes for which the specified prefix is an initial sub-string. |
output-modifiers | (Optional) For a list of associated keywords and arguments, use context-sensitive help. |
network-address | (Optional) IP address of a network in the BGP routing table. |
(Optional) Mask of the network address, in dotted decimal format. | |
(Optional) Displays only routes that have nonnatural net masks. | |
community | (Optional) Displays routes matching this community. |
(Optional) Displays routes matching this community list. | |
(Optional) Displays paths suppressed due to dampening (BGP route from peer is up and down). | |
filter-list | (Optional) Displays routes conforming to the filter list. |
(Optional) Displays flap statistics of routes. | |
inconsistent-as | (Optional) Displays only routes that have inconsistent autonomous systems of origin. |
neighbors | (Optional) Displays details about TCP and BGP neighbor connections. |
paths | (Optional) Displays path information. |
line | (Optional) A regular expression to match the BGP AS paths. |
(Optional) Displays information about peer groups. | |
(Optional) Displays routes matching the AS path "regular expression." | |
(Optional) Displays routes matching the AS path regular expression. | |
summary | (Optional) Displays BGP neighbor status. |
tags | (Optional) Displays incoming and outgoing BGP labels for each NLRI. |
No default behavior or values.
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
The following example shows output for all available VPNv4 information in a BGP routing table:
Router#show ip bgp vpnv4 all BGP table version is 18, local router ID is 14.14.14.14 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP,? - incomplete Network Next Hop Metric LocPrf Weight Path Route Distinguisher: 100:1 (vrf1) *> 11.0.0.0 50.0.0.1 0 0 101 i *>i12.0.0.0 13.13.13.13 0 100 0 102 i *> 50.0.0.0 50.0.0.1 0 0 101 i *>i51.0.0.0 13.13.13.13 0 100 0 102 i
Table 1 describes the fields shown in this example.
| Field | Description |
Network | Displays the network address from the BGP table. |
Displays the address of the BGP next hop. | |
Metric | Displays the BGP metric. |
Displays the local preference. | |
Weight | Displays the BGP weight. |
Path | Displays the BGP path per route. |
The following example shows how to display a table of labels for NLRIs that have a route-distinguisher value of 100:1.
Router#show ip bgp vpnv4 rd 100:1 tags
Network Next Hop In tag/Out tag
Route Distinguisher: 100:1 (vrf1)
2.0.0.0 10.20.0.60 34/notag
10.0.0.0 10.20.0.60 35/notag
12.0.0.0 10.20.0.60 26/notag
10.20.0.60 26/notag
13.0.0.0 10.15.0.15 notag/26
Table 2 describes the fields shown in this example.
| Field | Description |
Network | Displays the network address from the BGP table. |
Specifies the BGP next hop address. | |
In Tag | Displays the label (if any) assigned by this router. |
Out Tag | Displays the label assigned by the BGP next hop router. |
The following example shows VPNv4 routing entries for the VRF called vrf1.
Router#show ip bgp vpnv4 vrf vrf1 BGP table version is 18, local router ID is 14.14.14.14 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP,? - incomplete Network Next Hop Metric LocPrf Weight Path Route Distinguisher: 100:1 (vrf1) *> 11.0.0.0 50.0.0.1 0 0 101 i *>i12.0.0.0 13.13.13.13 0 100 0 102 i *> 50.0.0.0 50.0.0.1 0 0 101 i *>i51.0.0.0 13.13.13.13 0 100 0 102 i
Table 3 describes the fields shown in this example.
| Field | Description |
Network | Displays network address from the BGP table. |
Displays address of the BGP next hop. | |
Metric | Displays the BGP metric. |
Displays the local preference. | |
Weight | Displays the BGP weight. |
Path | Displays the BGP path per route. |
| Command | Description |
show ip vrf | Displays VRFs and associated interfaces. |
To display the CEF forwarding table associated with a VRF, use the show ip cef vrf EXEC command.
show ip cef vrf vrf-name [ip-prefix [mask [longer-prefixes]] [detail] [output-modifiers]]vrf-name | Name assigned to the VRF. |
(Optional) IP prefix of entries to show, in dotted decimal format (A.B.C.D). | |
mask | (Optional) Mask of the IP prefix, in dotted decimal format. |
longer-prefixes | (Optional) Displays table entries for all of the more specific routes. |
detail | (Optional) Displays detailed information for each CEF table entry. |
(Optional) For a list of associated keywords and arguments, use context-sensitive help. | |
interface | (Optional) Type of network interface to use: ATM, Ethernet, Loopback, POS (packet over SONET) or Null. |
interface-number | Number identifying the network interface to use. |
adjacency | (Optional) Displays all prefixes resolving through adjacency. |
discard | Discards adjacency. |
drop | Drops adjacency. |
glean | Gleans adjacency. |
null | Null adjacency. |
punt | Punts adjacency. |
non-recursive | (Optional) Displays only nonrecursive routes. |
summary | (Optional) Displays a CEF table summary. |
traffic | (Optional) Displays traffic statistics. |
prefix-length | (Optional) Displays traffic statistics by prefix size. |
unresolved | (Optional) Displays only unresolved routes. |
No default behavior or values.
EXEC
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
Used with only the vrf-name argument, the show ip cef vrf command shows a shortened display of the CEF table.
Used with the detail argument, the show ip cef vrf command shows detailed information for all CEF table entries.
This example shows the forwarding table associated with the VRF called vrf1.
Router#show ip cef vrf vrf1 Prefix Next Hop Interface 0.0.0.0/32 receive 11.0.0.0/8 50.0.0.1 Ethernet1/3 12.0.0.0/8 52.0.0.2 POS6/0 50.0.0.0/8 attached Ethernet1/3 50.0.0.0/32 receive 50.0.0.1/32 50.0.0.1 Ethernet1/3 50.0.0.2/32 receive 50.255.255.255/32 receive 51.0.0.0/8 52.0.0.2 POS6/0 224.0.0.0/24 receive 255.255.255.255/32 receive
Table 4 describes the fields shown in this example.
| Field | Description |
Prefix | Specifies the network prefix. |
Next Hop | Specifies the BGP next hop address. |
Interface | Specifies the VRF interface. |
| Command | Description |
Displays the IP routing table associated with a VRF. | |
Displays VRF interfaces. |
To display the routing protocol information associated with a VRF, use the show ip protocols vrf EXEC command.
show ip protocols vrf vrf-name
vrf-name | Name assigned to a VRF. |
No default behavior or values.
EXEC
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
Use this command to display routing information associated with a VRF.
The following example shows information about a VRF called vpn1:
Router#show ip protocols vrf vpn2
Routing Protocol is "bgp 100"
Sending updates every 60 seconds, next due in 0 sec
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
IGP synchronization is disabled
Automatic route summarization is disabled
Redistributing:connected, static
Routing for Networks:
Routing Information Sources:
Gateway Distance Last Update
13.13.13.13 200 02:20:54
18.18.18.18 200 03:26:15
Distance:external 20 internal 200 local 200
Table 5 describes the fields shown in this example.
| Field | Description |
Gateway | Displays the IP address of the router identifier for all routers in the network. |
Displays the metric used to access the destination route. | |
Last update | Displays the last time the routing table was updated from the source. |
| Command | Description |
show ip vrf | Displays VRF interfaces. |
To display the IP routing table associated with a VRF (VPN routing/forwarding instance), use the show ip route vrf EXEC command.
show ip route vrf vrf-name [connected] [protocol [as-number] [tag] [output-modifiers]]vrf-name | Name assigned to the VRF. |
connected | Displays all connected routes in a VRF. |
protocol | To specify a routing protocol, use one of the following keywords: bgp, egp, eigrp, hello, igrp, isis, ospf, or rip. |
Autonomous system number. | |
tag | IOS routing area label. |
output-modifiers | (Optional) For a list of associated keywords and arguments, use context-sensitive help. |
list number | Specifies the IP access list to display. |
profile | Displays the IP routing table profile. |
static | Displays static routes. |
summary | Displays a summary of routes. |
supernets-only | Displays supernet entries only. |
traffic-engineering | Displays only traffic-engineered routes. |
No default behavior or values.
EXEC
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
This command displays specified information from the IP routing table of a VRF.
This example shows the IP routing table associated with the VRF called vrf1:
Router#show ip route vrf vrf1
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR
T - traffic engineered route
Gateway of last resort is not set
B 51.0.0.0/8 [200/0] via 13.13.13.13, 00:24:19
C 50.0.0.0/8 is directly connected, Ethernet1/3
B 11.0.0.0/8 [20/0] via 50.0.0.1, 02:10:22
B 12.0.0.0/8 [200/0] via 13.13.13.13, 00:24:20
This example shows BGP entries in the IP routing table associated with the VRF called vrf1:
Router#show ip route vrf vrf1 bgp B 51.0.0.0/8 [200/0] via 13.13.13.13, 03:44:14 B 11.0.0.0/8 [20/0] via 51.0.0.1, 03:44:12 B 12.0.0.0/8 [200/0] via 13.13.13.13, 03:43:14
| Command | Description |
Displays the CEF forwarding table associated with a VRF. | |
Displays VRFs and associated interfaces. |
To display the set of defined VRFs (VPN routing/forwarding instances) and associated interfaces, use the show ip vrf EXEC command.
show ip vrf [{brief | detail | interfaces}] [vrf-name] [output-modifiers]brief | (Optional) Displays concise information on the VRF(s) and associated interfaces. |
detail | (Optional) Displays detailed information on the VRF(s) and associated interfaces. |
interfaces | (Optional) Displays detailed information about all interfaces bound to a particular VRF, or any VRF. |
vrf-name | Name assigned to a VRF. |
output-modifiers | (Optional) For a list of associated keywords and arguments, use context-sensitive help. |
When no optional parameters are specified the command shows concise information about all configured VRFs.
EXEC
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
Use this command to display information about VRFs. Two levels of detail are available: use the brief keyword or no keyword to display concise information, or use the detail keyword to display all information. To display information about all interfaces bound to a particular VRF, or to any VRF, use the interfaces keyword.
This example shows brief information for the VRFs currently configured:
Router#show ip vrf Name Default RD Interfaces vrf1 100:1 Ethernet1/3 vrf2 100:2 Ethernet0/3
Table 6 describes the fields shown in this example.
| Field | Description |
Name | Specifies the VRF name. |
Specifies the default route distinguisher. | |
Interfaces | Specifies the network interfaces. |
This example shows detailed information for the VRF called vrf1:
Router#show ip vrf detail vrf1 VRF vrf1; default RD 100:1 Interfaces: Ethernet1/3 Connected addresses are in global routing table Export VPN route-target communities RT:100:1 Import VPN route-target communities RT:100:1 No import route-map
Table 7 describes the fields shown in this example.
| Field | Description |
Interfaces | Specifies the network interfaces. |
Export | Specifies VPN route-target export communities. |
Import | Specifies VPN route-target import communities. |
This example shows the interfaces bound to a particular VRF:
router#show ip vrf interfaces Interface IP-Address VRF Protocol Ethernet2 130.22.0.33 blue_vrf up Ethernet4 130.77.0.33 hub up router#
Table 8 describes the fields shown in this example.
| Field | Description |
Interface | Specifies the network interfaces for a VRF. |
IP-Address | Specifies the IP address of a VRF interface. |
VRF | Specifies the VRF name. |
Protocol | Displays the state of the protocol (up/down) for each VRF interface. |
| Command | Description |
Enters VRF configuration mode. | |
rd | Configures a default route distinguisher (RD) for a VRF. |
route-target | Configures import and export extended community attributes for the VRF. |
import | Configures an import route map for a VRF. |
ip vrf forwarding | Associates a VRF with an interface or subinterface. |
vrf-name | Displays NLRIs associated with the named VRF. |
ip-prefix/length | (Optional) IP prefix address (in dotted decimal format) and length of mask (0 to 32). |
mask | (Optional) Destination network mask, in dotted decimal format. |
detail | (Optional) Displays detailed information on the VRF routes. |
output-modifiers | (Optional) For a list of associated keywords and arguments, use context-sensitive help. |
No default behavior or values.
EXEC
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
Use this command to display label forwarding entries associated with a particular VRF or IP prefix.
The following example shows label forwarding entries that correspond to the VRF called vpn1:
Router#show tag-switching forwarding vrf vrf1 detail
| Command | Description |
show tag-switching forwarding | Displays label forwarding information. |
show ip cef vrf | Displays VRFs and associated interfaces. |
This section documents new debug commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command references.
To display information related to processing BGPs, use the debug ip bgp EXEC command. To disable the display of BGP information, use the no form of this command.
debug ip bgp [A.B.C.D. | dampening | events | in | keepalives | out | updates | vpnv4]A.B.C.D. | (Optional) Displays the BGP neighbor IP address. |
dampening | (Optional) Displays BGP dampening. |
events | (Optional) Displays BGP events. |
in | (Optional) BGP inbound information. |
keepalives | (Optional) Displays BGP keepalives. |
out | (Optional) Displays BGP outbound information. |
updates | (Optional) Displays BGP updates. |
vpnv4 | (Optional) Displays VPNv4 NLRI information. |
No default behavior or values.
EXEC
| Release | Modification |
|---|---|
12.0(5)T | This command was introduced. |
The following example displays the output from this command:
Router#debug ip bgp vpnv4 03:47:14:vpn:bgp_vpnv4_bnetinit:100:2:58.0.0.0/8 03:47:14:vpn:bnettable add:100:2:58.0.0.0 / 8 03:47:14:vpn:bestpath_hook route_tag_change for vpn2:58.0.0.0/255.0.0.0(ok) 03:47:14:vpn:bgp_vpnv4_bnetinit:100:2:57.0.0.0/8 03:47:14:vpn:bnettable add:100:2:57.0.0.0 / 8 03:47:14:vpn:bestpath_hook route_tag_change for vpn2:57.0.0.0/255.0.0.0(ok) 03:47:14:vpn:bgp_vpnv4_bnetinit:100:2:14.0.0.0/8 03:47:14:vpn:bnettable add:100:2:14.0.0.0 / 8 03:47:14:vpn:bestpath_hook route_tag_chacle ip bgp *nge for vpn2:14.0.0.0/255.0.0.0(ok)
ATM-LSR---A label switch router with a number of LSC-ATM interfaces. The router forwards the cells among these interfaces using labels carried in the VPI/VCI field.
ATM edge LSR---A router that is connected to the ATM-LSR cloud through LSC-ATM interfaces. The ATM edge LSR adds labels to unlabeled packets and strips labels from labeled packets.
BGP---Border Gateway Protocol. Interdomain routing protocol that exchanges reachability information with other BGP systems. It is defined in RFC 1163.
CEF---Cisco Express Forwarding. An advanced Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with large and dynamic traffic patterns.
CE router---Customer edge router. A router that is part of a customer network and that interfaces to a provider edge (PE) router. CE routers are not aware of associated VPNs.
CoS---Class of Service. A feature that provides scalable, differentiated types of service across an MPLS network.
GRE---Generic routing encapsulation. A tunneling protocol developed by Cisco that can encapsulate a wide variety of protocol packet types inside IP tunnels, creating a virtual point-to-point link to Cisco routers at remote points over an IP internetwork. By connecting multiprotocol subnetworks in a single-protocol backbone environment, IP tunneling that uses GRE allows network expansion across a single-protocol backbone environment.
IGP---Interior Gateway Protocol. An Internet protocol used to exchange routing information within an autonomous system. Examples of common IBGPs include IGRP, OSPF, and RIP.
IS-IS---Intermediate system-to-intermediate system. OSI link-state hierarchical routing protocol in which ISs (routers) exchange routing information based on a single metric to determine network topology.
Label-switched path (LSP)---A sequence of hops (R0...Rn) in which a packet travels from R0 to Rn through label switching mechanisms. A label-switched path can be established dynamically, based on normal routing mechanisms, or through configuration.
Label-switched path (LSP) tunnel---A configured connection between two routers, in which MPLS is used to carry the packet.
LSA---Link-state advertisement. A broadcast packet used by link-state protocols. The LSA contains information about neighbors and path costs and is used by the receiving router to maintain a routing table.
MPLS---Multiprotocol Label Switching. An emerging industry standard.
NLRI---Network layer reachability information. BGP sends routing update messages containing NLRI to describe a route and how to get there. In this context, an NLRI is a prefix. A BGP update message carries one or more NLRI prefixes and the attributes of a route for the NLRI prefixes; the route attributes include a BGP next hop gateway address, community values, and other information.
PE router---Provider edge router. A router that is part of a service provider's network connected to a customer edge (CE) router. All VPN processing occurs in the PE router.
RD---Route distinguisher. An 8-byte value that is concatenated with an IPv4 prefix to create a unique VPN IPv4 prefix.
RIP---Routing Information Protocol. An IGP used to exchange routing information within an autonomous system, RIP uses hop count as a routing metric.
traffic engineering---The techniques and processes used to cause routed traffic to travel through the network on a path other than the one that would have been chosen if standard routing methods had been used.
traffic engineering tunnel---A label-switched path tunnel that is used for engineering traffic. It is set up through means other than normal Layer 3 routing and is used to direct traffic over a path different from the one that Layer 3 routing would cause it to take.
tunneling---Architecture providing the services necessary to implement any standard point-to-point data encapsulation scheme.
VPN---Virtual private network. A secure IP-based network that shares resources on one or more physical networks. A VPN contains geographically dispersed sites that can communicate securely over a shared backbone.
vpnv4---Used as a keyword in commands to indicate VPN-IPv4 prefixes. These prefixes are customer VPN addresses, each of which has been made unique by the addition of an 8-byte route distinguisher.
VRF---VPN routing/forwarding instance. A VRF consists of an IP routing table, a derived forwarding table, a set of interfaces that use the forwarding table, and a set of rules and routing protocols that determine what goes into the forwarding table. In general, a VRF includes the routing information that defines a customer VPN site that is attached to a PE router.
Posted: Wed Dec 8 10:54:02 PST 1999
Copyright 1989-1999©Cisco Systems Inc.