Hi,I am trying to bootstrap a yield curve using cash deposits, futures and swaps. In order to do that I need to make a convexity adjustment between futures and forward rate. In Hull's book this adjustment factor is given as 0.5 * sigma^2 * T1 * T2, where sigma is the volatility of the change in the short-term interest rate in 1 year, and T1 and T2 are the times to maturity and maturity of the underlying rate.To estimate sigma, I followed the method outlined in the paper "A practical guide to swap curve construction" as to use the implied volatility from interest rate caps. To calculate the implied volatility, I can get the market price for 1Y cap with 3 caplets and try to solve for the implied flat volatility. The problem is, to price a cap(let), I need the forward rate and the discount factor at each reset / payoffs points, which is what I am trying to solve in the first place (bootstrapping a yield curve). Isn't this just a chicken and egg problem?Is my understanding above correct? Or have I missed something? I am new to this area so any help would be greatly appreciated.Thanks.