Editing Fat tree (section)

{{Short description|Universal network for provably efficient communication}}
{{More citations needed|date=August 2007}}
[[File:fat tree network.svg|thumb|A fat tree]]
[[File:Fat-tree.svg|thumb|A 2-level fat tree with 8-port switches]]

The '''fat tree network''' is a universal [[Network theory|network]] for provably efficient communication.<ref name="CL85">{{cite journal |author-link=Charles E. Leiserson |first=Charles E |last=Leiserson |title=Fat-trees: universal networks for hardware-efficient supercomputing |journal=IEEE Transactions on Computers |volume=34 |issue=10 |pages=892–901 |date=October 1985 |doi=10.1109/TC.1985.6312192 |s2cid=8927584 |url=http://courses.csail.mit.edu/6.896/spring04/handouts/papers/fat_trees.pdf }}</ref> It was invented by [[Charles E. Leiserson]] of the [[Massachusetts Institute of Technology|MIT]] in 1985.<ref name="CL85" /> k-ary n-trees, the type of fat-trees commonly used in most high-performance networks, were initially formalized in 1997.<ref>{{Cite book |last=Petrini |first=Fabrizio |title=Proceedings 11th International Parallel Processing Symposium |chapter=K-ary n-trees: High performance networks for massively parallel architectures |date=1997 |chapter-url=https://ieeexplore.ieee.org/document/580853 |volume=doi: 10.1109/IPPS.1997.580853. |pages=87–93|doi=10.1109/IPPS.1997.580853 |isbn=0-8186-7793-7 |s2cid=6608892 }}</ref>

In a [[tree (data structure)|tree]] [[data structure]], every branch has the same thickness (bandwidth), regardless of their place in the hierarchy—they are all "skinny" (''skinny'' in this context means low-[[Bandwidth (computing)|bandwidth]]). In a fat tree, branches nearer the top of the hierarchy are "fatter" (thicker) than branches further down the hierarchy. In a [[telecommunications network]], the branches are [[data link]]s; the varied thickness (bandwidth) of the data links allows for more efficient and technology-specific use.{{citation needed|date=March 2016}}

[[Mesh topology|Mesh]] and [[hypercube internetwork topology|hypercube]] topologies have communication requirements that follow a rigid algorithm, and cannot be tailored to specific packaging technologies.<ref>{{cite book |first1=Charles E. |last1=Leiserson |first2=Zahi S. |last2=Abuhamdeh |first3=David C. |last3=Douglas |first4=Carl R. |last4=Feynman |first5=Mahesh N. |last5=Ganmukhi |first6=Jeffrey V. |last6=Hill |first7=W. |last7=Daniel Hillis |first8=Bradley C. |last8=Kuszmaul |first9=Margaret A. |last9=St. Pierre |first10=David S. |last10=Wells |first11=Monica C. |last11=Wong |first12=Shaw-Wen |last12=Yang |first13=Robert |last13=Zak |chapter=The Network Architecture of the Connection Machine CM-5 |title=SPAA '92 Proceedings of the fourth annual ACM symposium on Parallel algorithms and architectures |pages=272–285 |publisher=ACM |year=1992 |isbn=978-0-89791-483-3 |doi=10.1145/140901.141883 |s2cid=6307237 |chapter-url=https://dl.acm.org/citation.cfm?doid=140901.141883}}</ref>