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Link-State Routing

Which Method Is Better?: Distance-Vector vs. Link-State

When should distance-vector be used, and when should link-state routing be used? There are arguments for and against each approach.

The choice of strategy should be based on the properties of the given network, the main parameter being how frequently nodes are expected to go down or come up.

Stability:

  1. It is generally thought that link-state algorithms are more stable, because each router "knows" the entire network.
  2. On the other hand, if the network is highly dynamic, it is possible for link-state algorithms to create routing loops while new topology information is being disseminated.

Running Time:

  1. Link-state algorithms converge more quickly than distance-vector algorithms.
  2. In practice, the time for convergence depends on the network graph, the load on the routing protocol, and the exact sequence of link failure and recovery.

Overhead:

  1. Much of the overhead in link-state routing comes from the subroutine that prevents corruption of the LSP database in case of node and/or link failure. The distance-vector algorithm does not have this overhead.

Memory:

  1. Typically, link-state implementations require more memory than distance-vector implementations.
Conclusion

There is no clear winner between these two strategies, especially because for every positive feature of one protocol, a modification can be made to the other to make it competitive again.

 
 
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