MPLS Fundamentals

Label Stack Depth

To detect problems with labeled packets in the data plane, you need to know how many labels are present in the label stack of the packets at each point in the network. Only then can you figure out if the labeled packets have the right number of labels and if it is the correct label in the right place in the label stack. Therefore, you need to know for your network how many labels a labeled packet has at each link. The number of labels present in the label stack depends on the MPLS network design you have. Each network design has a particular number of labels associated with it. Look at some examples. Following are the simple scenarios and the number of labels associated with them:

1. Plain IPv4-over-MPLS: 1

2. MPLS VPN or Any Transport ...