http://muratbuffalo.blogspot.tw/2010/11/vl2-scalable-and-flexible-data-center.html
The key points from my point of view in this article for Data Center :
Agility:
- Without agility, each service must pre-allocate enough servers to meet difficult to predict demand spikes, or risk failure at the brink of success. With agility, the data center operator can meet the fluctuating demands of individual services from a large shared server pool, resulting in higher server utilization and lower costs. In order to achieve agility, assigning servers to a service should be independent of network topology.
- Still, downtimes can be significant, and with no obvious way to eliminate all failures from the top of the hierarchy, this paper's approach is to broaden (fatten) the topmost levels of the network so that the impact of failures is muted and performance degrades gracefully.
- The paper proposes to use valiant load balancing (vlb) to randomize end-to-end communication paths to cope with volatility and achieve load balancing. In this scheme, the ToR switch randomly chooses an intermediate switch (among many available options) on a per flow basis.
