This paper gives a generalized description of fat tree topology, and invented the notation:

This notation means the fat tree has height $h$, and on level $i$ ($0\le i\le h-1$) each node has $w_{i+1}$ parent nodes and $m_i$ children nodes. Level 0 is the bottom-most layer, so assumed $m_0=0$. So for the degree-3 fat-tree that I always use, it can be expressed by $XGFT(3;3,3,6;1,3,3)$.

## Bibliographic data

```
@inproceedings{
title = "On Generalized Fat Trees",
author = "Sabine R. Öhring and Maximilian Ibel and Sajal K. Das and Mohan J. Kumar",
booktitle = "Proc. 9th International Parallel Processing Symposium",
Mon = "Apr",
pages = "37--44",
address = "Santa Barbara, CA",
year = "1995",
}
```