Ch15.The Internet Protocol

Internetworking Terms

Example of Internet Protocol Operation

- What is "IP"? It's necessary information at Packet transmission
- What is "Header"? It's essential information when transmission any data
- Network Layer : Router, DataLink Layer : Bridge, Switch - Used when the two objects you want to connect are the same.
-> If two objects are different ? Using Gateway (ex. internet network - telephone network)
- ICMP : Protocol to handle when an event occurs during packet transmission, At this time, it is necessary to receive IP service.
 

 
- IP Design Issues
1. Routing 
2. Datagram(It's packet that each other independent Created at IP)
3. Fragmentation(It's cutting packet to constant unit, when trasmission size too big) and reassembly
4. Error control
5. Flow control
 

 
Header + payload , Header contains address
Address consists of two addresses which is Source address and destination address
TTL : Time to Live(Hope Count)
When transmission progress step by step, each step process caused TTL-1, So, arrived TTL == 0(or Hope count == 0), Packet is destroyed
packet destroyed issue is must be annuounced receiver, at this time we need "ICMP"

Routing

Fragmentation and Re-assembly

Packet size is too big -> Need to fragmentation
If No Fragmentation? Caused High Error Rate,
Fragmentation may occur at any stage of transmission.
So, re-assembly process is performed at the final stage.
 

- Transmission works independent, Cutting payload, then attach header information applicable information
 

• Error and Flow Control
  • Error Control
    • Discarded datagram identification is needed
    • Reasons for discarded datagrams include:
      • Lifetime expiration
      • Congestion
      • FCS error
  • Flow Control
    • Allows routers to limit the rate they receive data
    • Send flow control packets requesting reduced data flow