On the prevalence and characteristics of MPLS deployments in the open internet
On the prevalence and characteristics of MPLS deployments in the open internet
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DOI：
10.1145/2068816.2068858
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发表时间：
2011-11
期刊：
影响因子：
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通讯作者：
J. Sommers;P. Barford;Brian Eriksson
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文献类型：
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作者：
J. Sommers;P. Barford;Brian Eriksson
多协议标签交换（MPLS）是一种使服务提供商能够在IP网络中指定虚拟路径的机制。在开放互联网（即公共的端到端路径）中使用MPLS对用户和网络中立性具有重要影响，因为MPLS如今在流量工程应用中经常被使用。在本文中，我们对开放互联网中MPLS部署的普遍性和特征进行了一项纵向研究。我们使用了CAIDA Archipelago项目（Ark）在过去3.5年中收集的路径测量数据，这些数据包含了整个互联网中主机之间超过100亿条单独的 traceroute路径。我们使用两种不同的技术在Ark数据中识别MPLS路径：通过包含MPLS标签信息的ICMP扩展进行直接观察，以及使用贝叶斯数据融合方法进行推断。我们的直接观察方法只能识别统一模式的隧道，这很可能低估了MPLS的部署情况。尽管如此，我们的结果显示，在给定的测量周期内观察到的隧道总数随时间变化很大，在一级提供商中的部署量最大。大约7%的自治系统部署了MPLS，并且这种部署水平在过去三年中一直保持稳定。MPLS隧道的平均长度从2008年的4跳减少到2011年的3跳，并且路径长度分布严重倾斜。2011年，大约25%的所有路径至少穿过一个MPLS隧道，而4%的路径穿过不止一个。最后，在MPLS报头中观察到的数据表明，许多自治系统在其隧道中采用了某些类型的流量分类和工程技术。
Multi-Protocol Label Switching (MPLS) is a mechanism that enables service providers to specify virtual paths through IP networks. The use of MPLS in the open Internet (i.e., public end-to-end paths) has important implications for users and network neutrality since MPLS is frequently used in traffic engineering applications today. In this paper we present a longitudinal study of the prevalence and characteristics of MPLS deployments in the open Internet. We use path measurement data collected over the past 3.5 years by the CAIDA Archipelago project (Ark), which consist of over 10 billion individual traceroutes between hosts throughout the Internet. We use two different techniques for identifying MPLS paths in Ark data: direct observation via ICMP extensions that include MPLS label information, and inference using a Bayesian data fusion methodology. Our direct observation method can only identify uniform-mode tunnels, which very likely underestimates MPLS deployments. Nonetheless, our results show that the total number of tunnels observed in a given measurement period has varied widely over time with the largest deployments in tier-1 providers. About 7% of all autonomous systems deploy MPLS and this level of deployment has been consistent over the past three years. The average length of an MPLS tunnel has decreased from 4 hops in 2008 to 3 hops in 2011, and the path length distribution is heavily skewed. About 25% of all paths in 2011 cross at least one MPLS tunnel, while 4% cross more than one. Finally, data observed in MPLS headers suggest that many ASes employ some types of traffic classification and engineering in their tunnels.