Data capacity is the first thing that comes to mind while talking about large ceph clusters, or data storage systems in general. The number of drives is another measure to think about. And sometimes maximum iops is something to look out for, especially while considering a full-flash / nvme cluster. But heaviness? What does that even mean?
One of the most important and also the least understood part of kubernetes is cluster networking. I guess you already read through that and now you’re a bit confused about how to implement the required model, considering you were presented with about ~30 different options. A bit more googling would reduce that number to a few more popular choices. Nevertheless container networking is an involved subject and it’s easy to get lost in the details of any specific solution.