I haven't done it myself, but the answer is that depends on your IOS, equipment, and your links. After reading all the documentation, you should be able to make an informed decision as to whether your network can support encryption (most networks can).
why? the purpose of a frame relay network is to provide a private link between two sites. a frame relay link sold to you to connect two sites is private. no encryption necessary. that being said, if management wants it, then you should look into IPSEC. it is supported on most cisco boxes with 12.x IOS>
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...