Introducing the MPLS VPN-Tagging Server

Due to the limited number of available IPv4 addresses, private IP addresses are frequently used in MPLS L3VPN networks. In Example of overlapping IPs in MPLS-enabled VPNs, for example:

• Router PE1 uses IP address 10.1.0.2 on its interface that is facing router CE1, which is part of customer 2’s VPN.

• Router PE2 uses IP address 10.1.0.2 on its interface that is facing router CE5, which is in Customer 1’s VPN.

  Moreover, router PE2 has two interfaces with the same IP address, 10.5.0.2. One interface is facing router CE3, and the other is facing router CE4.

  Figure 1. Example of overlapping IPs in MPLS-enabled VPNs

  

  When a network device has two or more interfaces that share the same private IP address, known as overlapping IP addresses, IP Availability Manager cannot automatically create the related IP objects for those interfaces, and cannot correctly identify the related network connections for those interfaces.