Just a refresher, Frame-relay is connection-oriented but not-reliable right? It doesn't mean that if it is a connection-oriented it is automatically reliable right? Thanks.
Yes it can be connection oriented and not reliable. The essence of it is that connection oriented means a protocol that is aware end to end and tracks whether the remote device is connected (able to receive data) or not. Reliable means that if it detects an error in the data transmission that it is able to do something to correct it.