I'm sure some other experts might correct me if I'm wrong but logging is generally used for auditing where are snmp traps are mainly used for managment of devices. You can configure snmp to send snmp trap notifications to a CiscoWorks server and even configure them to email when an event happens. Some examples of traps would be environmental monitoring, port security, vlan creation/deletion , configuration change. We use snmp traps for significant events where we want to get immediately notified where as we log all access attempts to log into the switches. We look at the logs once a week audit whats been going on but we see the trap notifications as soon as trap is triggered.
I'm not at the office right now, but tomorrow monring I'll see what I can get for you but as for "mandatory" I don't think Cisco makes mandatory anything they just suggest and recommend certain things.
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...