Bandwidth is an important factor when becoming a Service Provider, insufficient bandwidth can stop your node being available to respond to requests from clients and miners on the network. Let’s look at the types of traffic each node type will need to respond to.
Sharders store the blocks of the blockchain. They need to store data and access and respond to queries very quickly to support the very fast block time and help maintain the network. Poorly performing sharders will earn less rewards and eventually be penalized. The bandwidth requirement is unlikely to be very large, but low latency is very important.
Miners administer transactions and perform challenges to blobbers to ensure data integrity. Again, bandwidth usage is not going to be huge but low latency is still important for miners in the active set. Blobber challenges by miners don’t have to be instant (outsourcing attacks are de-incentivized in other ways) so they can effectively be issued and responded to as a lower priority than critical tasks.
Blobbers store data and serve data direct to users as well as respond to challenges from miners. Overall bandwidth and speed is more important than latency, because data is only useful once it has been recieved in full.
The amount of bandwidth required is going to be roughly proportional to the amount of storage offered but could be very unpredictable due to surges in demand, certainly less predictable than miner or sharder traffic.
The bandwidth demand on blobbers offering Tens or certainly Hundreds of TB of data could easily max out even a Gigabit connection at times, so this needs to be taken into account.