Cisco Mpls Vpn

Configuring a Basic MPLS VPN
Document ID: 13733
Introduction
Prerequisites
Requirements
Components Used
Related Products
Conventions
Configure
Network Diagram
Configuration Procedures
Configurations
Verify
Troubleshoot
Related Information

Introduction
This document provides a sample configuration of a Multiprotocol Label Switching (MPLS) VPN when
Border Gateway Protocol (BGP)or Routing Information Protocol (RIP) is present on the customer's site.
When used with MPLS, the VPN feature allows several sites to interconnect transparently through a service
provider's network. One service provider network can support several different IP VPNs. Each of these
appears to its users as a private network, separate from all other networks. Within a VPN, each site can send
IPpackets to any other site in the same VPN.
Each VPN is associated with one or more VPN routing or forwarding instances (VRFs). A VRF consists of an
IP routing table, a derived Cisco express forwarding (CEF) table, and a set of interfaces that use this
forwarding table.
The router maintains a separate routing and CEF table for each VRF. This prevents information being sent
outside the VPN andallows the same subnet to be used in several VPNs without causing duplicate IP address
problems.
The router using Multiprotocol BGP (MP−BGP) distributes the VPN routing information using the MP−BGP
extended communities.
For more information about the propagation of updates through a VPN, refer to these documents:
• VPN Route Target Communities
• BGP Distribution of VPN Routing Information
•MPLS Forwarding

Prerequisites
Requirements
There are no specific requirements for this document.

Components Used
The information in this document is based on these software and hardware versions:
P and PE Routers
• Cisco IOS® Software Release 12.2(6h) includes the MPLS VPN feature.
• Any Cisco router from the 7200 series or higher supports P functionality. The Cisco 2691, as well asany 3640 series or higher router supports PE functionality.
C and CE Routers
• You can use any router that can exchange routing information with its PE router.
The information presented in this document was created from devices in a specific lab environment. All of the
devices used in this document started with a cleared (default) configuration. If you are working in a live
network, ensure thatyou understand the potential impact of any command before using it.

Related Products
To implement the MPLS feature, you must have a router from the range of Cisco 2600 or higher. To select the
required Cisco IOS with MPLS feature, use the Software Advisor ( registered customers only) . Also check for the
additional RAM and Flash memory required to run the MPLS feature in the routers.WIC−1T, WIC−2T, and
serial interfaces can be used.

Conventions
Refer to Cisco Technical Tips Conventions for more information on document conventions.
The letters below represent the different types of routers and switches used.
• PProvider's core router.
• PEProvider's edge router.
• CECustomer's edge router.
• CCustomer's router.
This diagram shows a typical configuration illustrating theconventions outlined above.

Configure
In this section, you are presented with the information to configure the features described in this document.
Note: Use the Command Lookup Tool ( registered customers only) to find more information on the commands
used in this document.

Network Diagram
This document uses this network setup:

Configuration Procedures
Refer to MPLS Virtual PrivateNetworks for more information.
Enabling ip cef
Use this procedure in order to enable ip cef. For improved performance, use ip cef distributed (where
available). Complete these steps on the PEs after MPLS has been set up (configuring tag−switching ip on the
interfaces).

1. Create one VRF for each VPN connected using the ip vrf
command.
When doing this:
♦ Specify the correct route...