Packet Processing Interface to Interface, Part 2: IP Header Check

• Media length >= 20 bytes

• Version = 4 (or 6)

• Header length >= 5

• Header length <= total length

• Checksum validation

• • Mandatory according to RFC1812, but many routers can be configured to skip this step!

• If link layer address was broadcast, IP address must be broadcast or multicast

• If link layer address was multicast, IP address must be multicast

• Discard Martians