Basically the problem of data center network may be the scalability. More precisely, the future data center networks may need following 5 requirements. 1 any VM can be migrated to any physical machine without changing IP address. 2 administrators should have "plug and play" deployment on switches. 3 end host can efficiently communicate with other end hosts within the data center 4 no forwarding loop 5 failure detection and recover should be efficient and fast. And of course, it is not easy to fulfill all these requirement based on existing techniques. Therefore, the authors proposes PortLand scheme.
The fundamental observation of PortLand is that data center networks are often physically inter-connected as a multi-rooted tree (e.g. fat tree). So the nugget of Portland is to employ a lightweight protocol for switches to discover their own position in the network topology. Basically, the location discovery is to let the switches send messages indicating the port directions. The key insight here is the edge switches only receive message from aggregation routers, whereas the aggregation routers receive messages from edges routers downwards facing the port.
Previous works mainly suffer from the scalability or cannot fulfill the 5 requirements mentioned above. Whereas PortLand can achieve all the requirements and easy to be scaled.
PortLand is designed for a unknown network topology. However, when you have a known topology, there is no need to build up such a system.
I think PortLand may be influential in ten years. Currently I think existing protocols works well in data center networks, there is no need to build up such a system. However, in the future, when the data center is huge, it may need to use PortLand protocol.
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