C / S client / server model
P2P Peer Connection client can act as a server, such as Thunder download
Data exchange
Circuit switching exchange packet-switched messages
1. The circuit switching: call
Three stages of circuit-switched: establishing a communication connection releases the connection
Establishing a connection that is looking for a connection line, after communication that is found with this special line to transmit data, required data transfer is complete release link
It can be seen long distances require multiple switch circuit switching, more busy, so expensive long distance calls
- Circuit switched data for a large amount of real-time exchange, such as voice, video
- May be used between the circuit switched core router
- Not flexible, there is the case where a circuit switched busy
2. The message exchange
Message exchange Direct TransferThe entire fileDelay high.
Storage transponder.
3. Packet Switched
A complete data packet segmentation and then sequentially transmits each part, each part of the final assembled. Generate additional overhead.
Packet switching busy situation does not exist.
Packet switching and packet switching are used in storage - forward switching mode
Difference: a complete packet switching packets "store - forward"; packet switching to smaller packets "store - forward"
When multiple users share a link, the link demand shared.
- Efficient, flexible and not busy
- Large overhead
- High delay
If the packet size M, the transmission rate is R, a total of n routers directly connected. The transmission time:
Note 1B = 8bit
In burst packet switched data transmission network.
May produce congestion (congestion): packet loss and delay, reliable data transfer protocol processing required and congestion control.
Packet switching allows more users to use network! - full sharing of network resources
Storage - packet switching the way forward
Packet switching is one of the modern computer networks important theoretical basis, data exchange technology is currently widely used in computer networks, and storage - forward is the basic workings of packet switching. Please discuss, whether the packet switching can take other work? What kind of advantages and disadvantages?
There are three ways forward: straight forward, store and forward and forward free of debris, the debris of which no forwarding is based on a new idea straight forward.
Through forwarding focus is no longer stored, not received a complete packet will be forwarded directly, it is clear that improved the transmission speed and reducing the size requirements of the router cache, but since no data packet is detected, the lost error checking method.
Non-fragmenting forward only on the basis of the cut-through, 64 bytes forwarding conditions, reduced forward error probability.