VPLS BGP Signaling

The two primary functions of the Virtual Private LAN Service (VPLS) control plane are autodiscovery and signaling. The VPLS BGP Signaling feature enables you to use BGP as both an autodiscovery and a signaling protocol for VPLS, in accordance with RFC 4761.

Prerequisites for VPLS BGP Signaling

You are familiar with the concepts in the “Configuring Virtual Private LAN Services” and the “VPLS Autodiscovery BGP Based” modules of the .

Information About VPLS BGP Signaling

Overview of VPLS BGP Signaling

Prior to the VPLS BGP Signaling feature, BGP was used for autodiscovery and Label Distribution Protocol (LDP) for signaling in accordance with RFC 6074. The VPLS BGP Signaling feature enables you to use BGP as the control plane protocol for both autodiscovery and signaling in accordance with RFC 4761.

As specified in RFC 4761, internal BGP (iBGP) peers will exchange update messages of the L2VPN AFI/SAFI with L2VPN information to perform both autodiscovery and signaling. The BGP multiprotocol Network Layer Reachability Information (NLRI) consists of a Route Distinguisher (RD), VPLS Endpoint ID (VE ID), VE Block Offset (VBO), VE Block Size (VBS), and Label Base (LB).

The figure below shows the format of the NLRI for RFC 4761.

Figure 1. RFC 4761 NLRI

Additional information, such as next-hop, route target (specified for a VPLS instance), and other Layer 2 data are carried in the BGP extended community attributes. A route target-based import/export mechanism similar to L3VPN is performed by BGP to filter L2VPN NLRIs of a particular VPLS instance.

Whether you use BGP signaling (RFC 4761) or LDP signaling (RFC 6074) depends on the commands you specify. To enable the VPLS BGP Signaling feature, use the autodiscovery bgp signaling bgp command in L2 VFI configuration mode. This command is supported on a per VPLS instance basis.

If a BGP session receives an invalid (that is, not matching the configuration) BGP update advertisement (update or withdraw), it is ignored.

BGP’s main task in supporting VPLS is route distribution via the L2VPN address family and interactions with L2VPN. Interactions between BGP and other components remain the same. Basic BGP functionalities like best-path selection, next-hop handling, and update generation, continue to operate in the same manner with VPLS BGP signaling. BGP RT constraint works seamlessly with the BGP VPLS Signaling feature.

The above example shows sample configuration on one PE. Similar configuration can be mirrored on other PEs.

How to Configure VPLS BGP Signaling

Configuring VPLS BGP Signaling

Procedure

  Command or Action Purpose
Step 1

enable

Example:


Device> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Device# configure terminal

Enters global configuration mode.

Step 3

l2vpn vfi context name

Example:


Device(config)# l2vpn vfi context vfi1

Establishes a L2VPN virtual forwarding interface (VFI) between two or more separate networks and enters Layer 2 VFI configuration mode.

Step 4

vpn id vpn-id

Example:


Device(config-vfi)# vpn id 100

Configures a VPN ID for the VPLS domain.

Step 5

autodiscovery bgp signaling {bgp | ldp} [template template-name]

Example:


Device(config-vfi)# autodiscovery bgp signaling bgp

Enables BGP signaling and discovery or LDP signaling and enters L2VPN VFI autodiscovery configuration mode.

Note 

For the VPLS BGP Signaling feature use the autodiscovery bgp signaling bgp command.

Step 6

ve id ve-id

Example:


Device(config-vfi-autodiscovery)# ve id 1001

Specifies the VPLS endpoint (VE) device ID value. The VE ID identifies a VFI within a VPLS service. The VE device ID value is from 1 to 16384.

Step 7

ve range ve-range

Example:


Device(config-vfi-autodiscovery)# ve range 12

Specifies the VE device ID range value. The VE range overrides the minimum size of VE blocks. The default minimum size is 10. Any configured VE range must be higher than 10.

Step 8

exit

Example:


Device(config-vfi-autodiscovery)# exit

Exits L2VPN VFI autodiscovery configuration mode and enters L2VPN VFI configuration mode.

Step 9

exit

Example:


Device(config-vfi)# exit

Exits L2VPN VFI configuration mode and enters global configuration mode.

Step 10

router bgp autonomous-system-number

Example:


Device(config)# router bgp 100

Enters router configuration mode to create or configure a BGP routing process.

Step 11

bgp graceful-restart

Example:


Device(config-router)# bgp graceful-restart

Enables the BGP graceful restart capability and BGP nonstop forwarding (NSF) awareness.

Step 12

neighbor ip-address remote-as autonomous-system-number

Example:


Device(config-router)# neighbor 10.10.10.1 remote-as 100

Configures peering with a BGP neighbor in the specified autonomous system.

Step 13

address-family l2vpn [vpls]

Example:


Device(config-router)# address-family l2vpn vpls
Specifies the L2VPN address family and enters address family configuration mode.

  • The optional vpls keyword specifies that VPLS endpoint provisioning information is to be distributed to BGP peers.

In this example, an L2VPN VPLS address family session is created.
Step 14

neighbor ip-address activate

Example:


Device(config-router-af)# neighbor 10.10.10.1 activate

Enables the neighbor to exchange information for the L2VPN VPLS address family with the local device.

Step 15

neighbor ip-address send-community [both | standard | extended]

Example:


Device(config-router-af)# neighbor 10.10.10.1 send-community extended
Specifies that a communities attribute should be sent to a BGP neighbor.

  • In this example, an extended communities attribute is sent to the neighbor at 10.10.10.1.

Step 16

neighbor ip-address suppress-signaling-protocol ldp

Example:


Device(config-router-af)# neighbor 10.10.10.1 suppress-signaling-protocol ldp
Suppresses LDP signaling and enables BGP signaling.

  • In this example LDP signaling is suppressed (and BGP signaling enabled) for the neighbor at 10.10.10.1.

Step 17

end

Example:


Device(config-router-af)# end

Exits address family configuration mode and returns to privileged EXEC mode.

Step 18

show bgp l2vpn vpls {all | rd route-distinguisher}

Example:


Device# show bgp l2vpn vpls all

(Optional) Displays information about the L2VPN VPLS address family.

Configuration Examples for VPLS BGP Signaling

Example: Configuring and Verifying VPLS BGP Signaling


l2vpn vfi context vfi1
 vpn id 100
 autodiscovery bgp signaling bgp
  ve id 1001
  ve range 10
 !
!
router bgp 100
 bgp graceful-restart
 neighbor 192.168.200.224 remote-as 100
 neighbor 192.168.200.224 update-source Loopback1
 !
 address-family l2vpn vpls
  neighbor 192.168.200.224 activate
  neighbor 192.168.200.224 send-community extended
  neighbor 192.168.200.224 suppress-signaling-protocol ldp
  exit-address-family
 !
show bgp l2vpn vpls all

Network                             Next Hop 			        Metric LocPrf Weight Path
Route Distinguisher: 100:100
*>100:100:VEID-1001:Blk-1001/136    10.0.0.0                             32768  ?    

*>i 100:100:VEID-1003:Blk-1000/136  192.168.200.224               0      100     0     ?

Additional References for VPLS BGP Signaling

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco IOS Master Command List, All Releases

BGP commands: complete command syntax, command mode, defaults, command history, usage guidelines, and examples.

Cisco IOS IP Routing: BGP Command Reference

Configuring Virtual Private LAN Services

Configuring Access Port

Configuring Virtual Private LAN Services,

VPLS Autodiscovery BGP Based

Standards and RFCs

Standard/RFC

Title

RFC 4761

Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling

RFC 6074

Provisioning, Auto-Discovery, and Signaling in Layer 2 Virtual Private Networks (L2VPNs)

Technical Assistance

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