The TLOC color-restrict attribute is a straightforward but, at the same time, very efficient way to control the topology in an environment with a small number of colors. However, in large-scale deployments with a mix of multiple public and multiple private colors, the restrict attribute is not flexible enough. If we look at the example shown in the diagram below, cEdge-2 has one connection to the MPLS cloud marked with the mpls color. That is why the second link to the MPLS on cEdge-2 must be marked with another private color, for example, metro-ethernet.