Previously we have seen, How to setup SAML based Single Sign On Where Salesforce will be Service Provider and some other application like AXIOM will be Identity Provider. In this article we will use one Salesforce Instance as Identity Provider and other Salesforce Instance as Service Provider.
Before starting you have to decide which salesforce Instance will act as Identity Provider and which one will act as Service Provider. To Avoid confusions, we can create app with different Logo to distinguish Identity Provider and Service Provider like I did.
Step 1 : Enable Domain in Identity Provider Organization
From Setup, click Domain Management | My Domain, enter a new subdomain name, and click Check Availability. If the name is available, click the Terms and Conditions check box, then click Register Domain.