You are absolutely correct, the case you are suggesting shall work, as R2 requires any PPP initiated to it to be PAP (ppp authentication pap) authenticated and since R1 can authenticate itself using PAP it will succeed and vice versa for R1 with CHAP (ppp authentication chap), i guessed that the original poster's question involved that each side is only configured with one different method as in and out.
Like Edison has said, you can change the username like you can on the calling router (the router initiating the session), but always keep in mind the router authenticating the other router (we'll call it the server) must have a local entry of this username in order to be able to authenticate the calling router with, as i've told you before on the other thread think of it as a client server issue.
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...