Long term bonds

hi Shail, I did allocate 6% of my portfolio to HDFC long duration couple of months back and now sitting at 4.49% absolute return since last 6 months.
With markets being very high i would like to reallocate 6% more from equity to debt. Do you suggest to choose HDFC long duration? I was reading somewhere that constant duration (or something similar sounding) may be a better choice as they adjust debt duration with the interest cycle.

regards