Measuring MPLS overhead A. Pescapè +* , S. P. Romano + , M. Esposito +* , S. Avallone + , G. Ventre +* * ITEM - Laboratorio Nazionale CINI per l’Informatica e la Telematica Multimediali Via Diocleziano, 328 80125 – Napoli ITALY + DIS, Dipartimento di Informatica e Sistemistica Università degli Studi Federico II di Napoli Via Claudio, 21 80125 – Napoli ITALY {pescape,spromano,mesposit,giorgio@unina.it}, avi.stefano@libero.it Abstract In this work we present a study of the MPLS overhead on Linux platform measuring the RTT (Round Trip Time). We compare the performance between two scenarios: the IP network and MPLS network. In this paper we show the results in three situations: connection oriented transport protocol (TCP), connectionless transport protocol (UDP) and network protocol (ICMP). We analyze the difference between IP and MPLS and for each protocol we study two type of network connection: back-to-back and shared connection. Finally we evaluate the overhead of the Label Stacking in the case of UDP. 1.0 Introduction MultiProtocol Label Switching (MPLS) is a technology that has received a great deal of attention in recent years. The IETF alone has produced over 300 Internet Drafts and numerous RFCs related to MPLS and continues its work on refining the standards. MPLS is a promising effort to provide the kind of traffic management and connection-oriented Quality of Service (QoS) support found in Asynchronous Transfer Mode (ATM) networks, to speed up the IP packet-forwarding process, and to retain the flexibility of an IP-based networking approach. MPLS has a strong role to play. MPLS reduces the amount of per-packet processing required at each router in an IP-based network, enhancing router performance even more. More significantly, MPLS provides significant new capabilities in four areas that have ensured its popularity: QoS support, traffic engineering, Virtual Private Networks (VPNs), and multiprotocol support [1]. There are several studies on the MPLS architecture and various works on the MPLS performance. These works are based on commercial equipments and regard the benefits of the use of MPLS to realize traffic engineering and other interesting topics like VPNs and QoS support. The work in this paper is based on freeware project (MPLS for Linux) to implement a MPLS stack for the Linux kernel. We’d like to use MPLS for Linux in order to realize a QoS aware architecture studying the problem concerning the interoperability between DiffServ and MPLS and other MPLS features. Therefore before to study the performance of the implemented solutions we’ve analyzed