ESSENTIAL BACKGROUND

---

NETWORK MODEL

• cost of storage servers: major issue
• purpose: minimize costs to make MOD servers affordable
• how to achieve that?
• hierarchical solutions
• caching
• sharing

• Hierarchical network model (fig. 10-5)
• international network ->
       national backbone networks ->
       regional backbone networks ->
       access (or neighborhood) networks ->
       homes
• the costs in this hierarchy can be reduced by exploiting spatial and temporal locality properties
• info/program caching: store documents that are likely to be requested often on the neighborhood servers and less frequently requested documents in higher levels of the hierarchy