I am facing serious troubles while calculating number of fragments. I read a formula #fragments = ceil (payload/ mtu-header) but this isn't giving correct answer in all the cases. Before I show my approach, I would like to ask what does PDU imply? Does it mean header is ... formula 1 #frags= ceil(17076/180)=95 Using formula 2, #frags= ceil(17076/176)=98 No match either. Where am I going wrong?