MPLS Label Distribution and Swapping
MPLS LDP VPN labels are not distributed or used in a sequential order. Instead, each router within an MPLS network independently determines label numbers based on its local label information base (LIB). These labels are assigned according to the router's policies and the available label space.
Labels for the same destination can differ across routers and do not follow a sequential pattern. When a packet moves through an MPLS network, routers perform label swapping, which is a core aspect of MPLS operations. The swapping is guided by the router's label forwarding information base (LFIB), which provides mappings from incoming to outgoing labels and next hops.
The outgoing label selected during the swap is chosen to ensure the packet follows the correct path but is not sequentially related to the incoming label. This process allows MPLS networks to efficiently manage and route traffic.