1. 處理
   1. forwarding
   2. routing
      1. Algorithm
2. Router
   1. input port
   2. switch fabric
   3. output port
   4. processor
      1. routing protocol
      2. maintain information
3. 資料
   1. datagram
4. Service
   1. Virtual-Circuit(VC)
      1. VC setup
         1. path
         2. numbers
         3. entries
      2. Data transfer
      3. VC teardown
   2. Datagram Networks
      1. longest prefix matching rule