Hi Aditya,

If you are expecting 123 marks in your jee advamce and belong to OBC category u will surely get into  IIT like IIT Ropar etc.

Now regarding your branch, so let me tell you there are different possibilities for getting your desired branch in different colleges. So the IIT which you would like to join u may or may not get the desired branch whereas in other you may surely get it. So getting a branch of own desire with this score is always a suspense till counselling.

Good Luck