Packet Switching Flashcards
What is packet switching?
method of communication of data across networks, it works by dividing data into a series of packets
How are packets routed?
using routers , they’re sent by any available route from source to destination, since each packet is self-contained so they can travel seperately
What does a packet consist of?
header
payload
trailer
What is contained within the header of the packet?
- sender IP
- receiver IP
- protocol being used (TCP/IP )
- packet number
- time to live or hop limit (time it takes for packet to expire)
What is contained within the payload?
The actual data
What is contained within the trailer?
- end of packet marker
- error correcting code
- checksum
Describe the process?
- data is broken into packets
- packets are sent by any available route from source to destination
- data is reassembled at the receiver based on the packet number
- the receiving node (IP address) has to confirm delivery, but if doesn’t then it sends a signal to source to retransmit
What does this technique allow?
The best use of the infrastructure as the packets can take any route, avoiding heavy traffic (congestion), broken paths etc.
What is a checksum?
Check if the data received hasn’t changed and safe (not corrupted), check if there has been any transmission errors
What are some disadvantages of packet switching?
- packets can get lost while taking alternative routes
- has latency and packets arrive out of order
What are some advantages of packet switching?
- bandwidth is efficiently used as packets can be routed around congestion
- charges apply on duration of connectivity, while circuit switching charges also on the distance
What happens if checksum is different than it should be?
packet is refused due to suspected corruption and a new copy is requested
