- what is the recommended minimum network connection bandwidth between nodes
(100M? 1G? >1G?)
- what is the recommended minimum network latency between nodes (<1ms?
- can one use the same 'affinityBackupFilter' strategy that is recommended
for distributing backup copies to nodes on separate racks, for distributing
backups to nodes in different datacentres (instead of different racks)? In
other words, can we have a cluster that is distributed between multiple
There are no strict requirement for network connection quality as you can
adjust network properties  for your particular case.
Talking about a cache distributed across two separate data centres is
totally fine. Just make sure that connection between them is stable and
think of a solution for potential network segmentation (split-brain) problem
in advance. Ignite does not support it out-of-the-box, but you can implement
your own solution based on SegmentationResolver  or look at third party
plugins which implemented it already.