Hi, the loopback address is logical interface within to your switch or router, with that said the good thing it can have any valid IP address assigned to it. not to be confused with the loopback address 127.0.0.1, the loopback interface can be included in routing protocols and function like any interface, once you configure your loopback interface it will be up and up and yes you can configure multible lookback interfaces.
Other responses have addressed the usefulness of the loopback interface and addressing on the loopback interface but not the aspect of now many loopback interfaces you can have. The number of loopback interfaces is limited by the number of IDBs on your router. Each interface, including loopbacks, requires an Interface Descriptor Block. The number of IDBs varies by platform and by version of code. You can find how many IDBs your router supports in the output of the command show idb.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...