IPv6, 2nd Edition

130 Part Two • IPv6 Protocols

Header checksum is a reasonably robust approach to avoiding the pro-

cessing of packets that have had their headers mangled en route

to their destination. However, with upper-layer protocols like TCP

and UDP calculating their own checksums on headers, the IPv4

header checksum was deemed superfluous. The cost of checking

the checksum en route is outweighed by the ease with which the

destination node can quickly determine that a packet has been

damaged by using transport or application layer checks. For those

applications that do actually require content authentication at the net-

work layer, the much more robust authentication ...