Hi Gunasekaran,
this is supported but with some limitations - depending on scenarios and document types. You have to setup middleware settings on both sides (CRM and ECC), prerequisite for replicating of transactions is also replicated master data and synchronized customizing.
Good way to start is to go through standard documentation at Data Exchange for Business Transactions - Business Transaction - SAP Library .
Full setup needs a bit of analysis of your needs and goes beyond simple answer but the documentation will lead you.
Regards,
Dawood.