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Configure an Anycast Gateway in an L2VPN

Configure a single IP address to function as an anycast gateway across multiple devices within a L2VPN.

Anycast is a networking feature where you can assign the same IP address to multiple devices in a network. Anycast enables the devices to use the same IP address as a default gateway for incoming traffic. The benefits of anycast include redundant connectivity and improved resiliency in the network.

In an MPLS network, PE devices typically assign unique inner VPN labels dynamically to identify the different VPN. The outer label is used to forward the packet across the service provider's core network, while the inner VPN label is used to identify a specific customer VPN. When you have multiple devices sharing an IP address for the gateway, dynamic label allocation can lead to inconsistencies in the VPN label. This causes duplicate entries in the routing table and inefficiencies in the network. Starting in Junos OS Release 25.4R1, we support static labels for each VPN site.

Figure 1 illustrates a topology of a L2VPN with an anycast IP address. The PE devices (PE3 and PE4) have different loopback addresses for the BGP protocol, but share an IP address for the anycast gateway. The sample configuration for configuring anycast address on PE3 is described below. Use a similar configuration for PE4.

Figure 1: Anycast Gateway in an L2VPN Anycast Gateway in an L2VPN
  1. Configure the interfaces. Assign one loopback address that can be used by as an identifier by BGP and another loopback address that can be used as an anycast IP address.
  2. Configure the policy statement to use the anycast IP address as the source for VPN traffic.
  3. Configure the BGP protocol to support L2VPN routing. Configure the route reflector as a neighbor and apply the export policy
  4. Configure an L2VPN routing instance with a unique static label for each local VPN site (CE2 and CE3).
    Note: The static label can be in the range of 16 through 983,615 in increments of 2. In other words, you cannot assign consecutive numbers for the static label.

Use the show l2vpn connections command to verify that the labels are being applied.