Question

the four key routing strategies are fixed,flooding, random and adaptive. Write the difference among the strategies.

Answer 1

Answer:
Fixed Routing:
·      A single permanent route is configured for each sourceto destination pair nodes
·       Determine routes usinga least cost algorithm
·      Routes are fixed, at least until there is a change innetwork topology
Flooding:
•       No network info is required
•       Operates as follows:
—   A packet is sent by a source node to every neighboringnode
—   At each node, incoming packets retransmitted on everylink except incoming link
—   Eventually a number of copies will arrive atdestination
—   Each packet is uniquely numbered so duplicates can bediscarded
—   Nodes can remember packets already forwarded to keepnetwork load in bounds
—   Can include a hop count in packets
Random Routing:
•       Node selects one outgoing path for retransmission ofincoming packet
•       Selection can be random or round robin
•       Can select outgoing path based on probabilitycalculation
•       No network info needed
•       Route is typically not least cost nor minimum hop
Adaptive Routing:
•       Used by almost all packet switching networks
•       Routing decisions change as conditions on the networkchange
—   Failure (node or trunk)
—   Congestion (portion of network is heavily loaded withtraffic)
•       Requires info about network
•       Decisions more complex
•       Tradeoff between quality of network info and overhead
•       Reacting too quickly can cause oscillation
•       Reacting too slowly can be irrelevant