Upside there is resistance @21950 and on downside there is major support @17000.
Looking at the RSI of the bank nifty, it can be say that BNF is in sideways zone for next few weeks, showing range bound between (17000-21950)
For 14th may expiry,
Supply zones @(20185-20360) / @(21130-21950)
Demand zones @(18700-18950) / @(17650-18100)
Resistance @ 21950
Major resistance @17000