Characterizing VLAN-induced sharing in a campus network

Many enterprise, campus, and data-center networks have complex layer-2 virtual LANs (“VLANs”) below the IP layer. The interaction between layer-2 and IP topologies in these VLANs introduces hidden dependencies between IP level network and the physical infrastructure that has implications for network management tasks such as planning for capacity or reliability, and for fault diagnosis. This paper characterizes the extent and effect of these dependencies in a large campus network. We first present the design and implementation of EtherTrace, a tool that we make publicly available, which infers the layer-2 topology using data passively collected from Ethernet switches. Using this tool, we infer the layer-2 topology for a large campus network and compare it with the IP topology. We find that almost 70% of layer-2 edges are shared by 10 or more IP edges, and a single layer-2 edge may be shared by as many as 34 different IP edges. This sharing of layer-2 edges and switches among IP p...

• Type: Conference
• Year: 2009
• Where: IMC
• Authors: Muhammad Mukarram Bin Tariq, Ahmed Mansy, Nick Feamster, Mostafa H. Ammar
• Keywords: IMC 2009, Internet Technology, IP Topology, Large Campus Network, Layer-2 Edges