You want to upgrade CAS from 1.3 to 2.3 by following upgrade path.
After the upgrade the settings>alerts of SNMP trap settings disappear unexpectedly.
This is a limitation of upgrading from CAS1.3 to 2.1.
Upgrading from Content Analysis 22.214.171.124 to 126.96.36.199.
Please reconfigure correct SNMP trap setting after upgrade by folllowing steps.