Improved Flooding Algorithms

Disadvantage : flooding really does flood the network with packets! When do they stop?

Partial Solutions :

• Do not retransmit packets on the link on which they arrived - they have already travelled from that direction.
• Each packet can include a hop count and after any hop count exceeds the diameter of the network the packet can be discarded.
• Acknowledgements need only be transmitted on the link on which the data packet arrived.
• As data packets arrive, each router can remember the link of minimum hop count on which it arrived - all subsequent packets for that destination go on that link.
• routers can keep a list of sequence numbers seen and if any packets are re-seen by any router they are discarded.

Examples: Three implementations of flooding are provided in .../resources/flooding.zip.
Please examine these as examples of Network Layer and Data Link Layer separation.