IS-IS was one of the earliest dynamic routing protocols to work with IP addresses. As such, it is not as complex as more recent protocols. However, IS-IS is a big step forward from simple static routing.

While IS-IS may be slow in response to network outages, static routing has zero response. The same is true for convergence—static routing has zero convergence. Both IS-IS and static routing have the limited hop count, so it is neither a strength nor a weakness.