Create a new model

FabricEval has builtin topology generator that takes in a high-level spec of the desired network and outputs a complete protobuf. It can be found at topology/topogen.py.

For example, a desired topology might have the following high-level spec:

Number of 40G (Gen 1) clusters: 22
Number of 100G (Gen 2) clusters: 22
Number of 200G (Gen 3) clusters: 21
cluster radix: 256 links
Number of AggrBlock per cluster: 1
Number of S3 nodes per AggrBlock: 4
Number of S2 nodes per AggrBlock: 4
Number of S1 nodes (ToR) per AggrBlock: 32
Number of ports on S2/S3 nodes: 128
Number of ports on S1 nodes: 32
S1 over-subscription: 1:3
ECMP table size (40G): 4K
ECMP table size (100G): 16K
ECMP table size (200G): 32K

The corresponding parameters are set in generateToy3(). Briefly speaking, the topology generator constructs clusters one-by-one, then it calls a StripingPlan class, which connects the clusters to each other in a balanced way (minimal difference in the number of links).

Users can build a new topology starting from copying the existing topology and then make modifications on top of it. Another low level approach to construct/modify a topology is to directly edit the protobuf file.

The fabrics provided by topogen such as “toy3”, “toy5”, “toy6”, “f1”, are constructed closely following Google’s Jupiter fabrics in terms of size, connectivity, heterogeneity etc.