1. PPP & CHAP -------------- - R4 must require R1 and R2 to authenticate using CHAP but R1 and R2 must not require R4 to authenticate means that you can't run command "ppp authentication chap" command on R1 and R2 and you cant use Username command on R1 and R2 otherwise it ask asuthentication from R4. - R1 and R2 cannot use ppp chap hostname, they can use ppp chap password with "Security". - Make sure that all CHAP passwords are shown in clear int the configuration - Use radius server at 6.6.44.200 as authentication server and fallback to the local AAA database in case the server is unreachable - Use "Singtel" as key required by the Radius server - Make sure AAA authentication does not affect any console or line VTY from any PPP devices (ensure that there is no username prompt either) - Use only default authentication list for both console and line VTY.
