Label space reduction in MPLS networks: how much can a single stacked label do?

  • Authors:

  • Fernando Solano;Thomas Stidsen;Ramon Fabregat;Jose Luis Marzo

  • Affiliations:

  • Institute of Telecommunications, Warsaw University of Technology, Warsaw, Poland and Broadband and Distributed Systems Group, University of Girona, Girona, Spain;Informatics and Mathematical Modeling Department, Danish Technical University, Lyngby, Denmark;Broadband and Distributed Systems Group, University of Girona, Girona, Spain;Broadband and Distributed Systems Group, University of Girona, Girona, Spain

  • Venue:
  • IEEE/ACM Transactions on Networking (TON)
  • Year:
  • 2008

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Abstract

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. In this article we propose a solution to these drawbacks achieved by stacking an additional label onto the packet header. We call this type of reduction Asymmetric Merged Tunnels (AMT). A fast framework for computing the optimal reduction using AMTs is proposed. Our simulations show that the label space can be reduced by up to 20% more than when label merging is used.