Packet switching (Edexcel GCSE Computer Science): Flashcards
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What is packet switching?
What is packet switching?
Method to send data by breaking it into smaller packets
What are packets?
What are packets?
Smaller chunks of data that travel independently across network
Can packets take different routes?
Can packets take different routes?
Yes, different packets can take different routes to same destination
What do routers do?
What do routers do?
Act as traffic directors for packets; decide best path across network
What is a routing table?
What is a routing table?
Digital map of network routers consult to find best route
Three parts of a packet
Three parts of a packet
Header, payload, footer
Packet header contents
Packet header contents
Destination/source IPs, sequence no., total packets, checksum
What is the payload?
What is the payload?
Actual data being transmitted in a packet
Packet footer contents
Packet footer contents
End of packet flag - signals packet data finishes
What is a checksum for?
What is a checksum for?
Mathematical value to detect errors during transmission
Network efficiency benefit of packet switching
Network efficiency benefit of packet switching
Packets can take alternative paths if routes congested
Reliability benefit of packet switching
Reliability benefit of packet switching
Only lost packets need resending, not entire file
How are packets reassembled?
How are packets reassembled?
Using sequence numbers to arrange in correct order
Error detection at destination
Error detection at destination
Checksums verify packets arrived intact and uncorrupted