2.1 Link-State Routing Protocol  
  2.1.5 Advantages and disadvantages of link-state routing  
The following list contains many of the advantages that link-state routing protocols have over the traditional distance vector algorithms, such as Routing Information Protocol (RIP v1) or Interior Gateway Routing Protocol (IGRP):
  • Link-state protocols use cost metrics to choose paths through the network. The cost metric reflects the capacity of the links on those paths.
  • Link-state protocols use triggered, flooded updates and can immediately report changes in the network topology to all routers in the network. This immediate reporting generally leads to fast convergence times.
  • Each router has a complete and synchronized picture of the network. Therefore, it is very difficult for routing loops to occur.
  • Routers always use the latest set of information on which to base their routing decisions because LSAs are sequenced and aged.
  • The link-state database sizes can be minimized with careful network design. This leads to smaller Dijkstra calculations and faster convergence.
  • Every router is capable of mapping a copy of the entire network architecture, at least of its own area of the network. This attribute can greatly assist troubleshooting.
  • Classless interdomain routing (CIDR) and variable-length subnet masking (VLSM) are supported.

The following are some disadvantages of link-state routing protocols:

  • They require more memory and processing power than distance vector routers, which can make link-state routing cost-prohibitive for organizations with small budgets and legacy hardware.
  • They require strict hierarchical network design, so that a network can be broken into smaller areas to reduce the size of the topology tables.
  • They require an administrator with a good understanding of link-state routing.
  • They flood the network with LSAs during the initial discovery process, which can significantly decrease the capability of the network to transport data. This flooding process can noticeably degrade the network performance depending on the available bandwidth and the number of routers exchanging information.