MPLS-Enabled Applications: Emerging Developments and New Technologies

8.7. SECURITY ISSUES

L3VPNs must provide the same security assurances as the alternative of connecting dispersed sites with circuits at Layer 2. The first security concern is the separation of traffic between VPNs. We have already seen that the L3VPN solution has built-in mechanisms for isolation of addressing plans, routing and forwarding. However, since L3VPNs operate over a shared infrastructure, additional concerns arise:

• Can traffic from one VPN 'cross over' into another VPN?

• Can a security attack on one VPN affect another VPN?

• Can a security attack against the service provider's infrastructure affect the VPN service?

Let us examine these separately below and see how the problem can occur and how it can be avoided.

8.7.1. Can traffic from one VPN 'cross over' into another VPN?

One of the most frequent configuration errors is to plug in the CE interface into the incorrect port on the PE. Thus, instead of belonging to VPN A the new site belongs to VPN B (recall that membership in a VRF is based on the interface).^[] Following such a misconfiguration it becomes possible to send traffic from one VPN to another, especially if the same addressing plan is used in both VPNs. If a routing protocol is running between CE and PE, the problem can be easily avoided by enabling authentication for the routing protocol exchanges. In the case of a misconfiguration, the routing session does not establish and routes are not exchanged between PE and CE.^[] In Chapter 13 discussing management of ...