Labeled BGP Support

This feature module describes how to add label mapping information to the Border Gateway Protocol (BGP) message that is used to distribute the route on the Cisco ASR 901 Series Aggregation Services Routers.

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 table at the end of this module.

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.

Prerequisites for Labeled BGP Support

  • Cisco IOS Release 15.2(2)SNG or a later release that supports Labeled BGP must be installed previously on the Cisco ASR 901 Series Aggregation Services Router.

Restrictions for Labeled BGP Support

  • The Cisco ASR 901 router supports only the client functionality of RFC 3107 and not its area border router (ABR) functionality.

  • The Cisco ASR 901 router does not support two label-pop (Label pop is the process of removing label header).

  • Four label push is not supported. Due to this limitation, Labeled BGP access (RFC 3107) with Remote LFA-FRR/TE-FRR is not supported, if it exceeds three labels.

Overview of Labeled BGP Support

The Labeled BGP Support feature provides the option to use the BGP update message (that is used to distribute the route) to re-distribute Multiprotocol Label Switching (MPLS) label mapped to that route. The label mapping information is added (using send-label option of RFC 3107) to the same BGP message that is used to distribute the route. This process is useful in inter-domain routing, and the Cisco ASR 901 router supports this functionality as well as the virtual private network (VPN) and virtual routing and forwarding (VRF) over Labeled BGP functionality.

VPN/VRF over RFC 3107

The VPN/VRF over Labeled BGP is a 3-label imposition process (VRF Label, BGP label, interior gateway protocols [IGP] label). The innermost label is VRF, followed by BGP (for RFC 3107), and IGP. This functionality allows the Cisco ASR 901 router to support a VRF over labeled BGP session with an ABR.

How to Configure Labeled BGP Support


Note
The TDM over Labeled BGP feature is supported effective with Cisco IOS Release 15.3(3)S. The configuration and restrictions for this feature are the same as that of Labeled BGP Support.

To configure Labeled BGP Support feature on the Cisco ASR 901 router, perform the steps given below:

Procedure

  Command or Action Purpose

Step 1

enable

Example:


Router> enable

Enables the privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Router# configure terminal

Enters the global configuration mode.

Step 3

router bgp peer-group-name

Example:


Router(config)# router bgp 100

Enters router configuration mode.

  • peer-group-name —Number of an autonomous system that identifies the router to other BGP routers and tags the routing information that is passed along. The valid values range from 1 to 65535.

Step 4

address family ipv4

Example:


Router(config-router)# address family ipv4

Configures the address family as IPv4 using standard IPv4 address prefixes.

Step 5

neighbor peer-group-name send-community

Example:


Router(config-router)# neighbor 172.16.70.23 send-community

Specifies that the communities attribute be sent to the neighbor at this IP address.

  • peer-group-name —Name of a BGP peer group.

Step 6

neighborpeer-group-name peer-group-name

Example:


Router(config-router)# neighbor 172.16.70.23 send-label

Configures the router to associate a BGP label to the prefix using the neighborpeer-group-nameactivate option.

Step 7

neighborpeer-group-nameactivate

Example:


Router(config-router)# neighbor 172.16.70.23 activate

Enables the exchange of information with a neighboring BGP router.

Configuration Example for Labeled Support

The following is a sample configuration of the Labeled BGP Support feature. 


!
router bgp 1000
 bgp router-id 100.111.13.23
 neighbor pan peer-group
 neighbor pan remote-as 1000
 neighbor pan update-source Loopback0
 neighbor 100.111.14.3 peer-group pan
 !
 address-family ipv4
  neighbor pan send-community
  neighbor pan send-label 
!The "send-label" option is used to associate a BGP label to the prefix.
  neighbor 100.111.14.3 activate
 exit-address-family
 !
 address-family vpnv4
  neighbor pan send-community extended
  neighbor 100.111.14.3 activate
 exit-address-family
 !
 address-family ipv4 vrf LTE12
  redistribute connected
 exit-address-family
!

Verifying Labeled BGP Support

To verify the Labeled BGP Support on the Cisco ASR 901 router, use the show commands given below:

Router# show bgp ipv4 unicast labels 


  Network          Next Hop      In label/Out label
  1.0.0.0          0.0.0.0         imp-null/nolabel
  10.13.22.2/31    0.0.0.0         imp-null/nolabel
  10.13.23.0/31    0.0.0.0         imp-null/nolabel
  10.70.1.0/30     0.0.0.0         imp-null/nolabel
  100.100.10.1/32  100.111.14.4    nolabel/558
                   100.111.14.3    nolabel/560
  100.100.13.23/32 0.0.0.0         imp-null/nolabel
  100.101.13.23/32 0.0.0.0         imp-null/nolabel
  100.111.13.23/32 0.0.0.0         imp-null/nolabel
  100.111.13.26/32 100.111.14.3    nolabel/534
                   100.111.14.4    nolabel/68
  100.111.15.1/32  100.111.14.3    nolabel/25
Router# show ip bgp labels
   Network          Next Hop      In label/Out label
   1.0.0.0          0.0.0.0         imp-null/nolabel
   10.13.22.2/31    0.0.0.0         imp-null/nolabel
   10.13.23.0/31    0.0.0.0         imp-null/nolabel
   10.70.1.0/30     0.0.0.0         imp-null/nolabel
   100.100.10.1/32  100.111.14.4    nolabel/563
                    100.111.14.3    nolabel/556
   100.100.13.23/32 0.0.0.0         imp-null/nolabel
   100.101.13.23/32 0.0.0.0         imp-null/nolabel
   100.111.13.23/32 0.0.0.0         imp-null/nolabel
   100.111.13.26/32 100.111.14.4    nolabel/561
                    100.111.14.3    nolabel/559
   100.111.15.1/32  100.111.14.4    nolabel/59
                    100.111.14.3    nolabel/57
   100.111.15.2/32  100.111.14.4    nolabel/62
                    100.111.14.3    nolabel/52
   100.112.1.1/32   100.111.14.4    nolabel/nolabel
                    100.111.14.3    nolabel/nolabel
   100.112.1.2/32   100.111.14.4    nolabel/nolabel
                    100.111.14.3    nolabel/nolabel
   100.112.1.3/32   100.111.14.4    nolabel/nolabel
                    100.111.14.3    nolabel/nolabel 
Router# show ip bgp vpnv4 all label
   Network          Next Hop      In label/Out label
Route Distinguisher: 236:236
   154.154.236.4/30 100.154.1.1     nolabel/14002
                    100.154.1.1     nolabel/14002
   154.154.236.8/30 100.154.1.1     nolabel/14002
                    100.154.1.1     nolabel/14002
   154.154.236.12/30
                    100.154.1.1     nolabel/14002
                    100.154.1.1     nolabel/14002
   154.154.236.16/30
                    100.154.1.1     nolabel/14002
                    100.154.1.1     nolabel/14002
   154.154.236.20/30
                    100.154.1.1     nolabel/14002
                    100.154.1.1     nolabel/14002
   154.154.236.24/30
                    100.154.1.1     nolabel/14002
                    100.154.1.1     nolabel/14002
Router# show ip vrf interface
Interface              IP-Address      VRF                              Protocol
Vl100                  113.23.12.1     LTE12 
Router# show ip bgp vpnv4 vrf LTE12 label
   Network          Next Hop      In label/Out label
Route Distinguisher: 6666:6666 (LTE12)
   113.22.12.0/24   100.111.13.22   nolabel/51
                    100.111.13.22   nolabel/51
   113.23.12.0/24   0.0.0.0         50/nolabel(LTE12)
   113.24.12.0/24   100.111.13.24   nolabel/32
                    100.111.13.24   nolabel/32
   115.1.12.0/24    100.111.15.1    nolabel/16024
                    100.111.15.1    nolabel/16024
   154.154.236.4/30 100.154.1.1     nolabel/14002
   154.154.236.8/30 100.154.1.1     nolabel/14002
   154.154.236.12/30
                    100.154.1.1     nolabel/14002
   154.154.236.16/30
                    100.154.1.1     nolabel/14002
   154.154.236.20/30
                    100.154.1.1     nolabel/14002
   154.154.236.24/30
                    100.154.1.1     nolabel/14002

To verify three Label Support, use the show ip cef vrf command as shown in the following example. 


Router# show ip cef vrf LTE12 113.22.12.0 internal
113.22.12.0/24, epoch 0, flags rib defined all labels, RIB[B], refcount 5, per-destination sharing
  sources: RIB
  feature space:
   IPRM: 0x00018000
   LFD: 113.22.12.0/24  0 local labels
        contains path extension list
  ifnums: (none)
  path 13E8A064, path list 13F49DC8, share 1/1, type recursive, for IPv4, flags must-be-labelled, recursive-via-host
    MPLS short path extensions: MOI flags = 0x0 label 51
  recursive via 100.111.13.22[IPv4:Default] label 51, fib 141253D8, 1 terminal fib, v4:Default:100.111.13.22/32
    path 12520C8C, path list 13F49C38, share 1/1, type attached nexthop, for IPv4
   MPLS short path extensions: MOI flags = 0x0 label 17
      nexthop 100.111.14.4 Vlan10 label 17, adjacency IP adj out of Vlan10, addr 10.13.23.1 13734C80
  output chain: label 22 label 51 label 17 TAG adj out of Vlan10, addr 10.13.23.1 143EDCA0
!You can see three labels in the output chain; of which 22 is VRF label, 51 is BGP label !and 17 is LDP label

Additional References

The following sections provide references related to Labeled BGP Support feature.

Related Documents

Related Topic

Document Title

Cisco IOS Commands

Cisco IOS Master Commands List, All Releases

Cisco ASR 901 Command Reference

Cisco ASR 901 Series Aggregation Services Router Command Reference

BGP Commands

Cisco IOS IP Routing: BGP Command Reference

Configuring BGP

Cisco IOS IP Configuration Guide, Release 12.2

Standards

Standard

Title

None

—

MIBs

MIB

MIBs Link

None

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

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

RFCs

RFC

Title

RFC-3107

Carrying Label Information in BGP-4

Technical Assistance

Description

Link

The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

http://www.cisco.com/techsupport

Feature Information for Labeled BGP Support

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 Labeled BGP Support

Feature Name

Releases

Feature Information

Labeled BGP Support

15.2(2)SNG

This feature was introduced on the Cisco ASR 901 routers.

The following sections provide information about this feature:

TDM over Labeled BGP

15.3(3)S

Support for TDM over Labeled BGP was introduced on the Cisco ASR 901 routers.