Configure R7 as the NTP server with R2 and Switch1 as clients with MD5 authentication, as demonstrated in the example following item 3.
Configure clock and time zone accordingly.
Hidden trick: The NTP master must be configured on R3 and R7 for Switch1 redundancy. Configure Virtual IP as the NTP server on Switch1:
<snip from R7> ntp authentication-key 1 md5 02050D480809 7 ntp master end r7#show ntp status Clock is synchronized, stratum 8, reference is 127.127.7.1 nominal freq is 250.0000 Hz, actual freq is 250.0000 Hz, precision is 2**24 reference time is C2724021.6452EDE7 (03:23:45.391 AST Mon May 19 2003) clock offset is 0.0000 msec, root delay is 0.00 msec root dispersion is ...