Label Space Reduction in MPLS Networks: How Much Can A Single Stacked Label Do?

摘要

Most network operators have considered reducing LSR label spaces (number of labels used) as a way of simplifying management of underlaying Virtual Private Networks (VPNs) and therefore reducing operational expenditure (OPEX). The IETF outlined the label merging feature in MPLS—allowing the configuration of MultiPoint-to-Point connections (MP2P)—as a means of reducing label space in LSRs. We found two main drawbacks in this label space reduction scheme: $a)$ it should be separately applied to a set of LSPs with the same egress LSR—which decreases the options for better reductions, and $b)$ LSRs close to the edge of the network experience a greater label space reduction than those close to the core. The later implies that MP2P connections reduce the number of labels asymmetrically.