When planning for a SharePoint deployment one of the key aspects to consider is network latency and bandwidth. These two parameters have to be examined wheather you are looking at a centralized deployment or distributed deployment.
So what is bandwidth and latency??
Bandwidth is the amount of data that you can send through the wire. For example 1Mbps stands for 1MB of data being sent per second through the wire.
Latency is the time taken by the data ( or packet) to travel from source to destination. For example : If you are located in Australia and are opening a SharePoint site which is hosted in Seattle ( USA) and if it takes 1/10th of a second to open that page, then the network latency between your machine and the machine hosting the site is 1/10th of a second. ( Do not forget to divide the round-trip result by two, because all measures are one way only, not round-trip. )
For SharePoint deployment we have some guidelines to consider with respect to bandwidth and latency. Below table summaries with different scenarios.
Considering the same example : If you are located in Australia and are opening a SharePoint site which is hosted in Seattle ( USA) then you should have a network bandwidth through which you can send up to 1.5 MB of data per second and you should be able to access the site with in 100 milli second.
No front-end Web server or application server should have more than 1 millisecond (ms) of latency between it and the database server. In practice, this generally means that you should keep all the servers in a farm in the same data center.
With respect to backup/restore of database in SharePoint 2010, network drives with 1 millisecond or less latency between them and the database server will perform well.
A simple way to know your latency is to use ping.exe.
Hope the information was simple to understand.