1. Data Exchange Packet switching  Packet switching breaks data in to packets before sending it through a network, then reassembles it at the other end – used on the internet. Direction of data Error control bits Data (payload) Packet identification Source address Destination address Checks for errors The data Where the data has come from Where data is going Knows how to reassemble packets

2. Data Exchange VoIP and packet switching CODECs to encode data Sender’s computer records a message using webcam and microphone Message is converted in to digital data, broken up in to packets and sent across the internet The received computer assembles and decodes so the data can be seen and heard Codecs to decode data

3. Data Exchange  Sends data across network efficiently  Big files can be sent whole  Small packets can choose different routes through the network and move more efficiently  Security benefit - if a packet is intercepted, the hacker will only have one part of the whole file Advantages Disadvantages  If one or more packets are lost of corrupted during transmission, the whole file will not be received correctly

4. Data Exchange Transmission mode  Ways in which devices on a network communicate with each other and transmit data Simplex – signals go in one direction Full-Duplex – Signals go in both directions Half- Duplex – Signals go in both directions but the devices don’t transmit at the same time