If you are adding (not replacing) a new NIC to an empty slot perform the procedure in ``Adding a NIC''.
If you are replacing a NIC, you must replace it with an identical NIC (same make and model).
When replacing, it is important to minimize the amount of time the old NIC is out of service before bringing up the new NIC because most communication protocols have timers or require that programs retransmit periodically. If too much time elapses before the new NIC is in service, connections might drop, programs that require retransmission might fail, or routes might be lost.
Because of the potential for timing and retransmission problems, the preferred approach is to configure a new NIC as a backup device, and fail over to it. Using this technique, there is almost no time lapse before the new NIC takes over, and you can configure the backup NIC before you actually need it. The recommended procedure, which makes use of both hot-plug and NIC failover capabilities, is in ``Failing over a NIC''.