e bounced a few times within a few minutes, it wreaked havoc with our VoIP environment. This network supported upward of 300 calls per second, SO bouncing links was a severe problem. The answer was IP route dampening, which was in a cutting-edge version of the code (this was EIGRP, not BGP, SO route dampening was not inherent in the protocol). Normally, I would never advocate using a cutting-edge release, but in this case, the feature was SO necessary to the continued successful operation of the network that we decided to go ahead. Luckily, the feature solved our problems without adding any new ones. A technology change If you had a T1 and now you have a DS3, you probably need to add a DS3 interface card to support the DS3. To increase performance Sometimes, companies simply outgrow their hardware. I've seen websites go from PIX 515s to 520s to 525s to Firewall Services Modules for no other reason than that they were exceeding the aggregate bandwidth the devices could handle. Chapter 41: Avoiding Frustration To increase simplicity I'm a big fan of integrated CSU/DSU WICs. If you have T1s that are still using CSU/DSUs with V.35 cables, you can eliminate connection points and separate devices by integrating the CSU/DSU into the router. This is a single example, but many similar situations exist. To increase reliability If you have one firewall, adding a second firewall SO they act as a failover pair increases the reliability of the network. High availability is a good thing and should be implemented whenever your budget allows. To lower costs If you can prove that upgrading some hardware or software will lower costs, up- grading is a viable option. An example is collapsing a router and a switch into a single 3750 multilayer switch. When you combine the two devices, you only need to have a maintenance contract on one, which might lower yearly maintenance costs. Why Change Control Is Your Friend If you've been working in a small company that's grown into a larger company or if you've moved from a smaller to a larger 