MPLS VPN—BGP Local Convergence

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Updated:July 25, 2011

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MPLS VPN—BGP Local Convergence

Table Of Contents

MPLS VPN—BGP Local Convergence

Finding Feature Information

Contents

Prerequisites for MPLS VPN—BGP Local Convergence

Restrictions for MPLS VPN—BGP Local Convergence

Information About MPLS VPN—BGP Local Convergence

How Link Failures Are Handled with BGP

How Links Are Handled with the MPLS VPN—BGP Local Convergence Feature

How Link Failures Are Detected

How to Enable MPLS VPN—BGP Local Convergence

Configuring MPLS VPN—BGP Local Convergence with IPv4

Prerequisite

Configuring MPLS VPN—BGP Local Convergence with IPv6

Prerequisite

Examples

Troubleshooting Tips

Configuration Examples for MPLS VPN—BGP Local Convergence

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for MPLS VPN—BGP Local Convergence

MPLS VPN—BGP Local Convergence

First Published: December 31, 2007

Last Updated: July 16, 20 10

This document provides information about reducing the downtime of a provider edge (PE) to customer edge (CE) link failure. It describes how to reroute PE-egress traffic onto a backup path to the CE, before BGP has re-converged. The Multiprotocol Label Switching (MPLS) VPN —BGP Local Convergence feature is also reffered to as "local protection".

Note The MPLS VPN—BGP Local Convergence feature only affects traffic exiting the VPN. Therefore, it cannot fully protect traffic end-to-end by itself.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for MPLS VPN—BGP Local Convergence" section.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

•Prerequisites for MPLS VPN—BGP Local Convergence

•Restrictions for MPLS VPN—BGP Local Convergence

•Information About MPLS VPN—BGP Local Convergence

•How to Enable MPLS VPN—BGP Local Convergence

•Configuration Examples for MPLS VPN—BGP Local Convergence

•Additional References

•Feature Information for MPLS VPN—BGP Local Convergence

Prerequisites for MPLS VPN—BGP Local Convergence

•Before this form of link protection can be enabled, the customer site must be connected to the provider site by more than one path.

•Both the main forwarding path and the redundant backup path must have been installed within BGP, and BGP must support lossless switchover between operational paths.

Note Any routing protocol can be used between the PE and CE as long as the path is redistributed into BGP. That includes: eBGP, RIP, EIGRP, IS-IS, OSPF, and static routing. Any next-hop core tunneling technology that is supported by BGP is also supported for protection, including MPLS, IP/L2TPv3, and IP/GRE. Enabling a Carrier's Carrier (CsC) protocol between the PE and CE is also supported. Inter-AS option A (back-to-back VRF) is supported because it is essentially the same as performing the PE-CE link protection in both AS's. However, inter-AS options B and C protection are not supported at this time.

•All Provider Edge routers that are serving as backup to the link must have assigned a unique Route Distinguisher to each Virtual Routing and Forwarding table involved with the link to ensure that the route reflectors advertise all available paths.

•Although not required, it is recommended that the backup PE (shown as "PE2" in Figure 2) should run the same Cisco IOS version that is running on the primary PE ("PE1") whose link with the CE will be protected; that is, Cisco IOS XE Release 3.1S , or a more recent version of the product.

Restrictions for MPLS VPN—BGP Local Convergence

•This feature only affects traffic exiting the VPN. Therefore, it cannot fully protect traffic end-to-end by itself.

•This link protection cannot be initiated during an HA stateful switchover (SSO). But links already configured with this protection before the switchover begins will remain protected after the switchover.

•When performing an ISSU downgrade from an image that does include this link protection to an image that does not support this feature, active protection will be halted when BGP routes are refreshed.

•The MPLS VPN - BGP Local Convergence for 6VPE/6PE feature supports the eBGP and static routing protocols only.

Information About MPLS VPN—BGP Local Convergence

To configure the MPLS VPN—BGP Local Convergence feature, you should understand the following concepts:

•How Link Failures Are Handled with BGP

•How Links Are Handled with the MPLS VPN—BGP Local Convergence Feature

•How Link Failures Are Detected

How Link Failures Are Handled with BGP

Within a Layer 3 VPN network, the failure of a PE-CE link can cause a loss of connectivity (LoC) to a customer site, which is detrimental to time-sensitive applications. Several factors contribute to the duration of such an outage:

•The time to detect the failure

•The programming of the forwarding

•The convergence of BGP (In large networks, the restored traffic arrival time at its destination varies according to the prefix.)

When BGP detects a PE-CE link failure, it removes all of the BGP paths through the failing link. BGP runs the bestpath algorithm on the affected prefixes and selects alternate paths for each prefix. These new paths (which typically include a remote PE) are installed into forwarding. The local labels are removed and BGP withdrawals are sent to all BGP neighbors. As each BGP neighbor receives the withdrawal messages (typically indirectly using route-reflectors), the bestpath algorithm is called and the prefixes are switched to an alternate path. Only then is connectivity restored.

How Links Are Handled with the MPLS VPN—BGP Local Convergence Feature

The MPLS VPN—BGP Local Convergence feature requires that the prefixes to be protected on a PE-CE link have at least one backup path that does not include that link. (See Figure 1.) The customer site must have backup paths to the provider site.

Figure 1 Figure 1 Network Configured with Primary and Backup Paths

The MPLS VPN—BGP Local Convergence feature reduces LoC time by sending the broken link's traffic over a backup path (as shown in Figure 2) instead of waiting for total network convergence. The local label is maintained for 5 minutes while prefixes switch from the failing local path to the backup path. Because the label is not freed as had been the usual practice, forwarding continues to take place.

The bestpath algorithm selects the backup path. Thus, the local label has been applied in place of the failed BGP bestpath label (which is sometimes called "label swapping"). Traffic is restored locally while the network propagation of the BGP withdrawal messages takes place. Eventually, the egress PE router converges and bypasses the local repair.

Figure 2 Figure 2 Network Using the Backup Path After a PE-CE Link Failure on the Primary Path

Note After the 5-minute label preservation, the local labels are freed. Any BGP prefix that is remote and is not part of a Carrier Supporting Carrier network does not have a local label and is removed. The delay in local label deletion does not modify normal BGP addition and deletion of BGP paths. Rather, BGP re-programs the new backup bestpath into forwarding as usual.

How Link Failures Are Detected

Local protection relies on BGP being notified of the interface failure. Detection can occur using either the interface drivers or the routing tables. If an interface or route goes down, the corresponding path in the routing table is removed and BGP will be notified using the routing APIs.

However, when the routing table cannot detect the failure (as when a Layer 2 switch goes down), BGP determines that a neighbor is down through use of its hold-down timer. However, that determination can be extremely slow because of the 3-minute default for BGP session time-out.

You can reduce the detection delay by either reducing the BGP session time-out interval (as described in the Configuring Internal BGP Features document) or by enabling the Bidirectional Forwarding Detection protocol within eBGP between the PE and CE. For complete instructions to enable BFD, see the Bidirectional Forwarding Detection document.

How to Enable MPLS VPN—BGP Local Convergence

This section contains the following information:

•Configuring MPLS VPN—BGP Local Convergence with IPv4

•Configuring MPLS VPN—BGP Local Convergence with IPv6

•Troubleshooting Tips

Configuring MPLS VPN—BGP Local Convergence with IPv4

Perform the following steps to configure MPLS VPN—BGP Local Convergence for IPv4 MPLS VPNs.

Prerequisite

Ensure that the CE is already connected to the PE by a minimum of two paths.

SUMMARY STEPS

1. enable

2. configure terminal

3. ip vrf vrf-name

4. rd (conditional)

5. protection local-prefixes

6. do show ip vrf detail

DETAILED STEPS
Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.
Step 3
ip vrf vrf-name
Example:

Router(config)# ip vrf vpn1
Enters VRF configuration mode. If no VRF routing table and Cisco Express Forwarding (CEF) table had been previously created for this named VRF, then this command also creates them, giving both tables the specified vrf-name (in this example, the name is vpn1).
Step 4

rd route-distinguisher

Example:

Router(config-vrf)# rd 100:3

(Optional). If no route distinguisher had been previously established for the named VRF, then it is necessary to enter this command.

The route-distinguisher value can be either an:

•autonomous system number followed by a colon and an arbitrary number (for example, 100:3)

or

•IP address followed by a colon and an arbitrary number (for example, 192.168.122.15:1).

Step 5

protection local-prefixes

Example:

Router(config-vrf)# protection local-prefixes

Allows a pre-configured backup path to carry traffic if the PE-CE link breaks by preserving the local prefixes while BGP reconverges.

Step 6

do show ip vrf detail

Example:

Router(config-vrf)# do show ip vrf detail

(Optional) Verifies that MPLS VPN—BGP Local Convergence has been configured. (See Examples.)
Configuring MPLS VPN—BGP Local Convergence with IPv6

Perform the following steps to configure MPLS VPN—BGP Local Convergence for IPv6 MPLS VPNs.

Prerequisite

Ensure that the CE is already connected to the PE by a minimum of two paths.

SUMMARY STEPS

1. enable

2. configure terminal

3. vrf definition vrf-name

4. rd (optional)

5. address-family [ipv4 | ipv6]

6. protection local-prefixes

7. do show ip vrf detail

DETAILED STEPS
Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode. Enter your password if prompted.

Step 2

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

vrf definition vrf-name

Example:

Router(config)# vrf definition vrf2

Enters VRF definition configuration mode. If no VRF routing table and Cisco Express Forwarding (CEF) table had been previously created for this named VRF, then this command also creates them, giving both tables the specified vrf-name (in this example, the name is vrf2).
Step 4
rd route-distinguisher
Example:

Router(config-vrf)# rd 100:3
(Optional) If no route distinguisher had been previously established for the named VRF, it is necessary to enter this command.

The route-distinguisher value can be either an:

•autonomous system number followed by a colon and an arbitrary number (for example, 100:3)

or

•IP address followed by a colon and an arbitrary number (for example, 192.168.122.15:1).
Step 5

address-family [ ipv4 | ipv6 ]

Example:

Router(config-vrf)# address-family ipv6

Enters address family configuration mode and specifies the IPv4 or IPv6 protocol.

Step 6

protection local-prefixes

Example:

Router(config-vrf-af)# protection local-prefixes

Allows a pre-configured backup path to carry traffic if the PE-CE link breaks by preserving the local prefixes while BGP reconverges.

Step 7

do show ip vrf detail

Example:

Router(config-vrf-af)# do show ip vrf detail

(Optional) Verifies that MPLS VPN—BGP Local Convergence has been configured. (See Examples.)
Examples

To verify that local link protection has been enabled, enter the VRF detail command show ip vrf detail. If the protection is enabled, the status message "Local prefix protection enabled" will be shown in the display:
Router# show ip vrf detail 
VRF vpn1 (VRF Id = 1); default RD 100:1; default VPNID <not set>
  Interfaces:
    AT1/0/1.1               
VRF Table ID = 1
  Export VPN route-target communities
    RT:100:1                
  Import VPN route-target communities
    RT:100:1                 RT:100:2                
  No import route-map
  No export route-map
  VRF label distribution protocol: not configured
  VRF label allocation mode: per-prefix
     Local prefix protection enabled
Troubleshooting Tips

•Ensure that a minimum of two paths are present for the protected prefix w.x.y.z in BGP in steady state condition on the PE. The path using the protected PE should be the BGP best-path before failover occurs. To view the configuration, enter the command show ip bgp vpnv4 vrf vpn w.x.y.z

•Ensure that local protection has been enabled in the protected PE by entering the show ip vrf detail command as shown in the "Examples" section.

•When route reflectors exist in the topology, ensure that each VRF has a unique route distinguisher.

Configuration Examples for MPLS VPN—BGP Local Convergence

The following examples show how MPLS VPN—BGP Local Convergence can prevent traffic loss after a link failure. You can display a detailed view of local link protection before, during, and after BGP convergence by using the show bgp vpnv4 and show mpls forwarding-table vrf commands as shown in the following 3-stage example.

Note The show bgp vpnv4 unicast command is equivalent to the show ip bgp vpnv4 command that existed in prior releases of Cisco IOS.

Example 1: Before the Link Failure

Both a primary path and a backup path have been configured:
PE1# show bgp vpnv4 unicast all 172.16.0.1 
BGP routing table entry for 100:1:172.16.0.1/32, version 2
Paths: (2 available, best #2, table v1)
Flag: 0x820
  Advertised to update-groups:
     1         
  100, imported path from 100:2:172.16.0.1/32
    172.16.0.6 (metric 21) from 172.16.0.7 (172.16.0.7)
      Origin incomplete, metric 0, localpref 100, valid, internal
      Extended Community: RT:100:0
      Originator: 172.16.0.6, Cluster list: 172.16.0.7
      mpls labels in/out 16/17
  100
    172.16.1.1 from 172.16.1.1 (172.16.0.1)
      Origin incomplete, metric 0, localpref 100, valid, external, best
      Extended Community: RT:100:0
      mpls labels in/out 16/nolabel
BGP routing table entry for 100:2:172.16.0.1/32, version 9
Paths: (1 available, best #1, no table)
Flag: 0x820
  Not advertised to any peer
  100
    172.16.0.6 (metric 21) from 172.16.0.7 (172.16.0.7)
      Origin incomplete, metric 0, localpref 100, valid, internal, best
      Extended Community: RT:100:0
      Originator: 172.16.0.6, Cluster list: 172.16.0.7
      mpls labels in/out nolabel/17
Label information for both paths can be displayed:
PE1# show bgp vpnv4 unicast all labels
Network          Next Hop      In label/Out label
Route Distinguisher: 100:1 (v1)
   172.16.0.1/32    172.16.0.6      16/17
                    172.16.1.1      16/nolabel
   172.16.0.5/32    172.16.0.4      nolabel/23
   172.16.0.22/32   0.0.0.0         17/nolabel(v1)
   172.16.0.44/32   172.16.0.4      nolabel/24
   172.16.0.66/32   172.16.0.6      nolabel/21
   172.16.1.0/24    172.16.1.1      18/nolabel
                    0.0.0.0         18/nolabel(v1)
   172.16.5.0/24    172.16.0.4      nolabel/25
   172.16.8.0/24    172.16.0.6      19/23
                    172.16.1.1      19/nolabel
Route Distinguisher: 100:2
   172.16.0.1/32    172.16.0.6      nolabel/17
   172.16.0.66/32   172.16.0.6      nolabel/21
   172.16.8.0/24    172.16.0.6      nolabel/23
The PE1 (see Figure 1) forwarding table contains BGP bestpath information:
PE1# show mpls forwarding-table vrf v1 172.16.0.1 detail
Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop    
Label      Label      or Tunnel Id     Switched      interface              
16         No Label   172.16.0.1/32[V] 570           Et0/0      172.16.1.1  
        MAC/Encaps=14/14, MRU=1504, Label Stack{}
        AABBCC000B00AABBCC000C000800 
        VPN route: v1
        No output feature configured
PE1#
Example 2: After the Link Failure and Before BGP Convergence

After the link failure on only one path, the backup path remains available (see Figure 2):
PE1# show bgp vpnv4 unicast all 172.16.0.1                    
BGP routing table entry for 100:1:172.16.0.1/32, version 19
Paths: (1 available, best #1, table v1)
  Not advertised to any peer
  100, imported path from 100:2:172.16.0.1/32
    172.16.0.6 (metric 21) from 172.16.0.7 (172.16.0.7)
      Origin incomplete, metric 0, localpref 100, valid, internal, best
      Extended Community: RT:100:0
      Originator: 172.16.0.6, Cluster list: 172.16.0.7
      mpls labels in/out 16/17
BGP routing table entry for 100:2:172.16.0.1/32, version 9
Paths: (1 available, best #1, no table)
  Not advertised to any peer
  100
    172.16.0.6 (metric 21) from 172.16.0.7 (172.16.0.7)
      Origin incomplete, metric 0, localpref 100, valid, internal, best
      Extended Community: RT:100:0
      Originator: 172.16.0.6, Cluster list: 172.16.0.7
      mpls labels in/out nolabel/17
The label information for the backup path label can be displayed:
PE1# show bgp vpnv4 unicast all labels      
Network          Next Hop      In label/Out label
Route Distinguisher: 100:1 (v1)
   172.16.0.1/32    172.16.0.6      16/17
   172.16.0.5/32    172.16.0.4      nolabel/23
   172.16.0.22/32   0.0.0.0         17/nolabel(v1)
   172.16.0.44/32   172.16.0.4      nolabel/24
   172.16.0.66/32   172.16.0.6      nolabel/21
   172.16.1.0/24    172.16.0.6      nolabel/22
   172.16.5.0/24    172.16.0.4      nolabel/25
   172.16.8.0/24    172.16.0.6      19/23
Route Distinguisher: 100:2
   172.16.0.1/32    172.16.0.6      nolabel/17
   172.16.0.66/32   172.16.0.6      nolabel/21
   172.16.1.0/24    172.16.0.6      nolabel/22
   172.16.8.0/24    172.16.0.6      nolabel/23
The PE1 (see Figure 1) forwarding table contains new label and next-hop information to direct traffic onto the backup path:
PE1# show mpls forwarding-table vrf v1 172.16.0.1 detail                
Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop    
Label      Label      or Tunnel Id     Switched      interface              
16         17         172.16.0.1/32[V] 0             Et1/0      172.16.3.2  
        MAC/Encaps=14/22, MRU=1496, Label Stack{21 17}
        AABBCC000D00AABBCC000C018847 0001500000011000
        VPN route: v1
        No output feature configured
PE1#
Example 3: After Local Label Expiration and BGP Re-convergence

Because the local label preservation window has expired, the replacement local label is now gone from the PE1 forwarding table information:
PE1# show mpls forwarding-table vrf v1 172.16.0.1 detail
Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop    
Label      Label      or Tunnel Id     Switched      interface              
None       17         172.16.0.1/32[V] 0             Et1/0      172.16.3.2  
        MAC/Encaps=14/22, MRU=1496, Label Stack{21 17}
        AABBCC000D00AABBCC000C018847 0001500000011000
        VPN route: v1
        No output feature configured
The new BGP information reverts to the configuration shown in Figure 1:
PE1# show bgp vpnv4 unicast all 172.16.0.1 
BGP routing table entry for 100:1:172.16.0.1/32, version 23
Paths: (1 available, best #1, table v1)
  Not advertised to any peer
  100, imported path from 100:2:172.16.0.1/32
    172.16.0.6 (metric 21) from 172.16.0.7 (172.16.0.7)
      Origin incomplete, metric 0, localpref 100, valid, internal, best
      Extended Community: RT:100:0
      Originator: 172.16.0.6, Cluster list: 172.16.0.7
      mpls labels in/out nolabel/17
BGP routing table entry for 100:2:172.16.0.1/32, version 9
Paths: (1 available, best #1, no table)
  Not advertised to any peer
  100
    172.16.0.6 (metric 21) from 172.16.0.7 (172.16.0.7)
      Origin incomplete, metric 0, localpref 100, valid, internal, best
      Extended Community: RT:100:0
      Originator: 172.16.0.6, Cluster list: 172.16.0.7
      mpls labels in/out nolabel/17
PE1# show bgp vpnv4 unicast all labels 
Network          Next Hop      In label/Out label
Route Distinguisher: 100:1 (v1)
   172.16.0.1/32    172.16.0.6      nolabel/17
   172.16.0.5/32    172.16.0.4      nolabel/23
   172.16.0.22/32   0.0.0.0         17/nolabel(v1)
   172.16.0.44/32   172.16.0.4      nolabel/24
   172.16.0.66/32   172.16.0.6      nolabel/21
   172.16.1.0/24    172.16.0.6      nolabel/22
   172.16.5.0/24    172.16.0.4      nolabel/25
   172.16.8.0/24    172.16.0.6      nolabel/23
Route Distinguisher: 100:2
   172.16.0.1/32    172.16.0.6      nolabel/17
   172.16.0.66/32   172.16.0.6      nolabel/21
   172.16.1.0/24    172.16.0.6      nolabel/22
   172.16.8.0/24    172.16.0.6      nolabel/23
PE1# 
Additional References

The following sections provide references related to the MPLS VPN—BGP Local Convergence feature.

•Related Documents

•Standards

•MIBs

•RFCs

•Technical Assistance

Related Documents

Related Topic

Document Title

Configuration of VRF under the specific cases of IPv4 and IPv6 situations.

MPLS VPN—VRF CLI for IPv4 and IPv6 VPNs

Protocol for quickly detecting failed forwarding paths.

Bidirectional Forwarding Detection

BGP Configuration

Configuring a Basic BGP Network

Standards

Standard

Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

—

MIBs

MIB

MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

RFCs

RFC

Title

RFC 2547

BGP/MPLS VPNs

Technical Assistance

Description

Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for MPLS VPN—BGP Local Convergence

Table 1 lists the features in this module and provides links to specific configuration information.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 1 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Table 1 Feature Information for MPLS VPN—BGP Local Convergence

Feature Name

Releases

Feature Information

MPLS VPN—BGP Local Convergence

Cisco IOS XE Release 3.1S

This feature reduces the downtime of a PE-CE link failure by rerouting PE-egress traffic onto a backup path to the CE before BGP has re-converged.

The following command was modified: protection local-prefixes.

MPLS VPN - BGP Local Convergence for 6VPE/6PE

Cisco IOS XE Release 3.1S

This feature implements MPLS VPN—BGP Local Convergence for Cisco IOS VPN IPv6 provider edge routers (6VPE) and Cisco IOS IPv6 provider edge routers (6PE) over MPLS.

The following command was modified: protection local-prefixes.

Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

© 2010 Cisco Systems, Inc. All rights reserved.

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	ip vrf vrf-name Example: Router(config)# ip vrf vpn1	Enters VRF configuration mode. If no VRF routing table and Cisco Express Forwarding (CEF) table had been previously created for this named VRF, then this command also creates them, giving both tables the specified vrf-name (in this example, the name is `vpn1`).
Step 4	rd route-distinguisher Example: Router(config-vrf)# rd 100:3	(Optional). If no route distinguisher had been previously established for the named VRF, then it is necessary to enter this command. The route-distinguisher value can be either an: •autonomous system number followed by a colon and an arbitrary number (for example, `100:3`) or •IP address followed by a colon and an arbitrary number (for example, `192.168.122.15:1`).
Step 5	protection local-prefixes Example: Router(config-vrf)# protection local-prefixes	Allows a pre-configured backup path to carry traffic if the PE-CE link breaks by preserving the local prefixes while BGP reconverges.
Step 6	do show ip vrf detail Example: Router(config-vrf)# do show ip vrf detail	(Optional) Verifies that MPLS VPN—BGP Local Convergence has been configured. (See Examples.)

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	vrf definition vrf-name Example: Router(config)# vrf definition vrf2	Enters VRF definition configuration mode. If no VRF routing table and Cisco Express Forwarding (CEF) table had been previously created for this named VRF, then this command also creates them, giving both tables the specified vrf-name (in this example, the name is `vrf2`).
Step 4	rd route-distinguisher Example: Router(config-vrf)# rd 100:3	(Optional) If no route distinguisher had been previously established for the named VRF, it is necessary to enter this command. The route-distinguisher value can be either an: •autonomous system number followed by a colon and an arbitrary number (for example, `100:3`) or •IP address followed by a colon and an arbitrary number (for example, `192.168.122.15:1`).
Step 5	address-family [ ipv4 \| ipv6 ] Example: Router(config-vrf)# address-family ipv6	Enters address family configuration mode and specifies the IPv4 or IPv6 protocol.
Step 6	protection local-prefixes Example: Router(config-vrf-af)# protection local-prefixes	Allows a pre-configured backup path to carry traffic if the PE-CE link breaks by preserving the local prefixes while BGP reconverges.
Step 7	do show ip vrf detail Example: Router(config-vrf-af)# do show ip vrf detail	(Optional) Verifies that MPLS VPN—BGP Local Convergence has been configured. (See Examples.)

Related Topic	Document Title
Configuration of VRF under the specific cases of IPv4 and IPv6 situations.	MPLS VPN—VRF CLI for IPv4 and IPv6 VPNs
Protocol for quickly detecting failed forwarding paths.	Bidirectional Forwarding Detection
BGP Configuration	Configuring a Basic BGP Network

Standard	Title
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.	—

MIB	MIBs Link
No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.	To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

RFC	Title
RFC 2547	BGP/MPLS VPNs

Description	Link
The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.	http://www.cisco.com/cisco/web/support/index.html

Table 1 Feature Information for MPLS VPN—BGP Local Convergence
Feature Name	Releases	Feature Information
MPLS VPN—BGP Local Convergence	Cisco IOS XE Release 3.1S	This feature reduces the downtime of a PE-CE link failure by rerouting PE-egress traffic onto a backup path to the CE before BGP has re-converged. The following command was modified: protection local-prefixes.
MPLS VPN - BGP Local Convergence for 6VPE/6PE	Cisco IOS XE Release 3.1S	This feature implements MPLS VPN—BGP Local Convergence for Cisco IOS VPN IPv6 provider edge routers (6VPE) and Cisco IOS IPv6 provider edge routers (6PE) over MPLS. The following command was modified: protection local-prefixes.

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