Anthony Sequiera's post on study strategy reminded me to look over RIP. One bit of confusion here. The command reference for RIP says this about the invalid timer:
Interval of time (in seconds) after which a route is declared invalid; it should be at least three times the value of the update argument. A route becomes invalid when there is an absence of updates that refresh the route. The route then enters into a holddown state. The route is marked inaccessible and advertised as unreachable. However, the route is still used for forwarding packets. The default is 180 seconds.
So I understand this as after the invalid timer expires, the route is placed into holddown. THEN the route is in the holddown state waiting for that timer to expire before an alternate path is used. Problem is, Vol 1 (v4.1) RIP shows the timers for invalid and holdown as both 3 to meet the convergence time of 5 seconds. In that case, I see those 2 timers as running parallel. And seeing as they are both default of 180, is that the case?
The Doc CD has a habit of wording documentation in a way that seems to go against configurations I view in the WB's. So parallel or in sequence with these timers?