Why in a IPV4 packet, checksum is calculated against the IP header and not the entire packet like transport protocols tcp/udp?

ipv4
kuchiku picture kuchiku · Feb 9, 2012 · Viewed 8k times · Source

Why in a IPV4 packet, checksum is calculated against the IP header and not on the data like transport protocols tcp/udp?

Answer

sarnold picture sarnold · Feb 9, 2012

It's a matter of speed: the Internet backbone routers direct millions of packets per second and calculating a checksum over the entire contents would drastically slow down the packet processing.

The IPv6 specification removes even the header checksum to allow routers to route packets even faster. (It's just one of many steps IPv6 has taken to reduce the amount of time routers must inspect every packet. It all adds up.) Discarding corrupted packets is now placed entirely on end nodes.

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