Hello Aspirant,

CASB round is a special round to fill all the vacant seats in NITs , IIITs, GFTIs etc. In this round your common all India rank will be considered ,your category rank will only be considered if there is any vacancy in your category group/quota. Your CRL rank is the you secured among the total number of candidates who wrote the exam. You may checkout the below link to know more about this counselling round.

https://engineering.careers360.com/articles/csab-special-round-for-nits-iiits-and-gftis

All the best