Dear Jithin,
Here is the Steps to create Trusted RFC:
Step 1) Create Role and assign to the role to userin both System.
Step 2) Create of Dummy RFC in 1st System (ECC Client XXX) to 2nd System (CRM Client XXX).
Step 3) Create of Dummy RFC in 2nd System (CRM Client XXX) to 1st System (ECC Client XXX).
Step 4) Create Trusting Relationship from 2nd System (CRM Client XXX) to 1st System (ECC Client XXX). Using T-Code SMT1.
Step 5) Check Status of Trusted RFC (From 2nd System (CRM Client XXX) to 1st System (ECC Client XXX)). Using T-Code SMT2.
Step 6) Create Trusting Relationship from 1st System (ECC Client XXX) to 2nd System (CRM Client XXX). Using T-Code SMT1.
Step 7) Check Status of Trusted RFC (From 1st System (ECC Client XXX) to 2nd System (CRM Client XXX)). Using T-Code SMT2.
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Regards,
Amit