I am going through the routing protocols area of my CCNA now and one thing keeps niggling in the back of my mind.
Depending on the size of the network and the mission critical aspect of the organisation's network traffic obviously, is it better to switch all your routes to static once the best routes have been figured out in order to cut out the twice a minute router swapping of dynamic data between each other when it isn't needed?
If you have enough staff to quickly sort out any downed link/device that may crop up from time to time, why would you need the consant dynamic updates?
Dynamic routing protocols are nice and should be used where ever possible. They allow things like multi-pathing that static routes can't easily provide. They also make management easier, as once they are setup, they take care of themselves for the most part.
It mainly depends on the size of the network, the number of routers, the amount of redundancy you need, etc.
I'm not going to say one is better than the other, but I use dynamic protocols where ever I can.
As far as updates go, the amount of bandwidth used by updates is negligable. Some protocols, like eigrp, allow you set specify the amount of bandwidth you will allow the protocol to use for updates. This is very helpful low speed links.
At my previous job, I used eigrp for 40+ frame relay circuits ranging from 128k to 512k. I set up the bandwidth limit to 8k and had no issues with lost/delayed updates.
At my current job, we are a wireless ISP, and I use OSPF on all of our routers. Our network is a ring around the city, and OSPF does an incredible job choosing the best path. Convergence when a link drops is under 30 seconds, so most customers never even notice the path change.
Our connections to the internet are using BGP, with static routes to the providers routers.
Whether using static, dynamic, or a combination of them, your best bet is to research and design your network carefully, and then choosing a protocol accordingly.
choosing between dynamic and static depends a lot about network design, topology, alternative paths, size and complexity.
so it must be carefully analized so to choose between dynamic or static, also once you choose dynamic, you must also analyze other factors to choose the dynamic routing protocol you choose.
And if you choose static you must be careful to examine all your failover scenarios, backup links and topology possibilities to make sure your routing scheme allows for them and does the right thing in each circumstance