Table Of Contents
Supported Standards, MIBs, and RFCs
Verifying the VPN ID Configuration
MPLS VPN ID
Feature History
Release Modification12.0(17)ST
This feature was introduced.
12.2(4)B
Support for this feature was integrated into Cisco IOS Release 12.2(4)B.
This document describes the MPLS VPN ID feature in Cisco IOS Release 12.2(4)B and includes the following sections:
•Supported Standards, MIBs, and RFCs
Feature Overview
Using Multiprotocol Label Switching (MPLS) VPN ID you can identify virtual private networks (VPNs) by a VPN identification number, as described in RFC 2685. This implementation of the MPLS VPN ID feature is used for identifying a VPN. The MPLS VPN ID feature is not used to control the distribution of routing information or to associate IP addresses with MPLS VPN ID numbers in routing updates.
Multiple VPNs can be configured in a router. You can use a VPN name (a unique ASCII string) to reference a specific VPN configured in the router. Alternately, you can use a VPN ID to identify a particular VPN in the router. The VPN ID follows a standard specification (RFC 2685). To ensure that the VPN has a consistent VPN ID, assign the same VPN ID to all the routers in the service provider network that services that VPN.
You can use several applications to manage VPNs by VPN ID. For more details on how server applications use the VPN ID, refer to the "Benefits" section.
Note Configuration of a VPN ID for a VPN is optional. You can still use a VPN name to identify configured VPNs in the router. The VPN name is not affected by the VPN ID configuration. These are two independent mechanisms to identify VPNs.
Virtual Route Forwarding (VRF)
For each VPN that is configured in a router, the router creates a VRF instance. The VPN ID is stored in the corresponding VRF structure for the VPN.
The VRF table is a key element in the MPLS VPN technology. VRF tables exist on provider edge (PE) routers only. More than one VRF table can exist on a PE router. A VPN can contain one or more VRF tables on a PE router.
A VRF contains the routing information that defines the customer VPN site that is attached to a PE router. A VRF consists of the following elements:
•An IP routing table
•A derived Cisco Express Forwarding (CEF) table
•A set of interfaces that use the forwarding table
•A set of rules and routing protocols that determine what goes into the forwarding table
An IP routing table and the CEF table store packet forwarding information for each VRF. Another routing table and CEF table for each VRF prevent information from being forwarded outside a VPN and prevent packets that are outside a VPN from being forwarded to a router within the VPN.
Components of the VPN ID
Each VPN ID defined by RFC 2685 consists of the following elements:
•An Organizational Unique Identifier (OUI), a three-octet hex number
The IEEE Registration Authority assigns OUIs to any company that manufactures components under the ISO/IEC 8802 standard. The OUI is used to generate universal LAN MAC addresses and protocol identifiers for use in local and metropolitan area network applications. For example, an OUI for Cisco Systems is 00-03-6B (hex).
•A VPN index, a four-octet hex number, which identifies the VPN within the company.
Use the vpn id command and specify the VPN ID in the following format:
vpn id oui:vpn-index
A colon separates the OUI from the VPN index. See the vpn id command reference page for more information.
DHCP
Using DHCP network administrators can centrally manage and automate the assignment of IP addresses in an organization's network. The DHCP application uses the VPN ID as follows:
Step 1 A VPN DHCP client requests a connection to a PE router from a VRF interface.
Step 2 The PE router determines the VPN ID associated with that interface.
Step 3 The PE router sends a request with the VPN ID and other information for assigning an IP address to the DHCP server.
Step 4 The DHCP server uses the VPN ID and IP address information to process the request.
Step 5 The DHCP server sends a response back to the PE router, allowing the VPN DHCP client access to the VPN.
Remote Authentication Dial-In User Service
A Remote Authentication Dial-In User Service (RADIUS) server (or daemon) provides authentication and accounting services to one or more client network access servers (NASs). RADIUS servers authenticate users and return all configuration information necessary for the client to deliver service to the users.
Typically, a user login consists of a query (Access-Request) from the NAS to the RADIUS server and a corresponding response (Access-Accept or Access-Reject) from the server.
•The Access-Request packet contains the user name, encrypted password, NAS IP address, VPN ID, and port. The format of the request also provides information on the type of session that the user wants to initiate.
•The RADIUS server returns an Access-Accept response if it finds the user name and verifies the password. The response includes a list of attribute-value pairs that describe the parameters to be used for this session. If the user is not authenticated an Access-Reject is sent by the RADIUS server and access is denied.
Benefits
The MPLS VPN ID feature provides the following benefits:
•Remote access applications, such as the Remote Authentication Dial-In User Service (RADIUS) and Dynamic Host Configuration Protocol (DHCP), can use the MPLS VPN ID feature to identify a VPN. RADIUS can use the VPN ID to assign dial-in users to the proper VPN, based on each user's authentication information.
•A VPN is private and uses a private address space that might also be used by another VPN or by the Internet. The IP address used in a VPN is only significant to the VPN in which it exists. The VPN ID identifies the VPN to which the IP address belongs.
•The MPLS VPN ID feature standardizes the VPN identification method, as described in RFC 2685.
Restrictions
The MPLS VPN ID feature has the following restrictions:
•The VPN ID is not used to control the distribution of routing information or to associate IP addresses with VPN IDs in routing updates.
•Configure all the PE routers that belong to the same VPN with the same VPN ID. Make sure the VPN ID is unique to the Service Provider network.
Related Documents
The following documents provide more information about the MPLS VPN ID feature:
Cisco Documentation
•Cisco IOS Security Configuration Guide, Release 12.2
•Cisco IOS Security Command Reference, Release 12.2
•Introduction to Cisco MPLS VPN Technology
•DHCP Relay Support for MPLS VPN Suboptions
•MPLS Virtual Private Networks
Other Documentation
The list of public OUI assignments:
http://standards.ieee.org/regauth/oui/oui.txtSupported Platforms
This feature is supported on the following platforms:
•Cisco 7200 series
Availability of Cisco IOS Software Images
Platform support for particular Cisco IOS software releases is dependent on the availability of the software images for those platforms. Software images for some platforms may be deferred, delayed, or changed without prior notice. For updated information about platform support and availability of software images for each Cisco IOS software release, refer to the online release notes or Cisco Feature Navigator.
Supported Standards, MIBs, and RFCs
Standards
•IEEE Std 802-1990, IEEE Local and Metropolitan Area Networks: Overview and Architecture
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
RFCs
•RFC 2685—Virtual Private Networks Identifier
Prerequisites
Each VRF configured on a PE router can have a VPN ID configured. Configure all the PE routers that belong to the same VPN with the same VPN ID. Make sure the VPN ID is unique to the Service Provider network.
Configuration Tasks
See the following sections for configuration tasks for the MPLS VPN ID feature. Each task in the list is identified as either optional or required.
•Specifying a VPN ID (required)
•Verifying the VPN ID Configuration (optional)
Specifying a VPN ID
To specify a VPN ID on a PE router, perform the following steps beginning in global configuration mode:
Verifying the VPN ID Configuration
To display information about the VRF tables on the PE router, use the show ip vrf command. This example displays three VRF tables called "vpn1", "vpn2", and "vpn5".
Router# show ip vrf
Name Default RD Interfacesvpn1 100:1 Ethernet1/1Ethernet1/4vpn2 <not set>vpn5 500:1 Loopback2To ensure that the PE router contains the VPN ID you specified, issue the show ip vrf id command. The following example shows that only VRF tables "vpn1" and "vpn2" have VPN IDs assigned. The VRF table called "vpn5" is not displayed, because it does not have a VPN ID.
Router# show ip vrf idVPN Id Name RD2:3 vpn2 <not set>A1:3F6C vpn1 100:1This command displays all the VPN IDs that are configured on the router, their associated VRF names, and VRF route distinguishers (RDs). If a VRF table in the PE router has not been assigned a VPN ID, that VRF entry is not included in the output. See the show ip vrf command reference page for more information.
To see all the VRFs on a PE router, issue the show ip vrf detail command:
Router# show ip vrf detailVRF vpn1; default RD 100:1; default VPNID A1:3F6CInterfaces:Ethernet1/1 Ethernet1/4Connected addresses are not in global routing tableExport VPN route-target communitiesRT:100:1Import VPN route-target communitiesRT:100:1 RT:500:1No import route-mapNo export route-mapVRF vpn2; default RD <not set>; default VPNID 2:3No interfacesConnected addresses are not in global routing tableNo Export VPN route-target communitiesNo Import VPN route-target communitiesNo import route-mapNo export route-mapVRF vpn5; default RD 500:1; default VPNID <not set>Interfaces:Configuration Examples
This section provides the following example of configuring a VPN ID:
Configuring a VPN ID
The following example updates the VPN ID assigned to the VRF table called "vpn1":
Router# configuration terminal
Enter configuration commands, one per line. End with CNTL/Z.Router(config)# ip vrf vpn1Router(config-vrf)# vpn id a1:3f6cRouter(config-vrf)# endCommand Reference
This section documents modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.2 command reference publications.
show ip vrf
To display the set of defined VRFs and associated interfaces, use the show ip vrf command in privileged EXEC mode.
show ip vrf [{brief | detail | interfaces | id}] [vrf-name] [output-modifiers]
Syntax Description
When no optional parameters are specified, the command shows concise information about all configured VRFs.
Command Modes
Privileged EXEC
Command History
Usage Guidelines
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. To display information about VPN IDs assigned to a PE router, use the id keyword.
Examples
This example shows brief information for the VRFs currently configured:
Router# show ip vrfName Default RD Interfacesvrf1 100:1 Ethernet1/3vrf2 100:2 Ethernet0/3Table 1 describes the fields shown in this example.
Table 1 show ip vrf Field Descriptions
Field DescriptionName
Specifies the VRF name.
Default RD
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 vrf1VRF vrf1; default RD 100:1 default VPNID A1:3F6CInterfaces:Ethernet1/3Connected addresses are in global routing tableExport VPN route-target communitiesRT:100:1Import VPN route-target communitiesRT:100:1No import route-mapTable 2 describes the significant fields shown in the output.
This example shows the interfaces bound to a particular VRF:
Router# show ip vrf interfacesInterface IP-Address VRF ProtocolEthernet2 130.22.0.33 blue_vrf upEthernet4 130.77.0.33 hub uprouter#Table 3 describes the significant fields shown in the output.
This example displays all the VPN IDs that are configured in the router and their associated VRF names and VRF route distinguishers (RDs).
Router# show ip vrf idVPN Id Name RD2:3 vpn2 <not set>A1:3F6C vpn1 100:1Table 4 describes the significant fields shown in the output.
Table 4 show ip vrf id Field Descriptions
Field DescriptionVPN ID
Specifies the VPN ID assigned to the VRF.
Name
Specifies the VRF name.
RD
Specifies the route distinguisher.
Related Commands
vpn id
To set or update a VPN ID on a VRF, use the vpn id command in VRF configuration mode. To remove the VPN ID from the VRF, use the no form of this command. To change the VPN ID, issue the command again. The new ID overwrites the old one.
vpn id oui:vpn-index
no vpn id [oui:vpn-index]
Syntax Description
Defaults
By default, the VPN ID is not set.
Command Modes
VRF configuration
Command History
Release Modification12.0(17)ST
This command was introduced.
12.2(4)B
This command was integrated into Cisco IOS Release 12.2(4)B.
Usage Guidelines
Each VRF configured in a PE router can have a VPN ID. Use the same VPN ID for the PE routers that belong to the same VPN. Make sure the VPN ID is unique for each VPN in the Service Provider network.
Examples
In the following example, the VPN ID of 0000a100003f6c is assigned to a VRF called "vpn1":
Router(config)# ip vrf vpn1Router(config-vrf)# vpn id a1:3f6cRelated Commands