Pros of building Network Switch / Router.

Cost
Simple and reliable
- Pager of ours rings. Thus has the motivation to keep it simple.
- Single source of requirement. (AWS)
Speed to debug / fix issues
- No need to duplicate in other sites. No one has the same scale of an environment to test.

Notes:

25G = 1 wave, 40G = 4 waves (4x10Gbps).
Tomahawk .. did not hear it's custom ASIC
Custom silicon = small silicon with 2x25GbE offloading server load.
Offloading to hardware will provide 1/10 latency, 1/10 power, 1/10 cost.
Reducing latency is difficult. Hardware = us/ns -> Software = ms.
Storage
- 2014 : 880 disks/rack
- now: 1110 disks/rack. 8.8~11PB in a rack. 2778 lbs of storage.