UDP checksum Goal:detect "errors"(e.g.,flipped bits)in transmitted segment Sender: Receiver: treat segment contents ▣compute checksum of as sequence of 16-bit received segment integers check if computed checksum checksum:addition(1's equals checksum field value: complement sum)of o NO-error detected segment contents O YES-no error detected. ▣sender puts checksum But maybe errors value into UDP checksum nonetheless?More later field . Transport Layer 3-18Transport Layer 3-18 UDP checksum Sender:  treat segment contents as sequence of 16-bit integers  checksum: addition (1’s complement sum) of segment contents  sender puts checksum value into UDP checksum field Receiver:  compute checksum of received segment  check if computed checksum equals checksum field value:  NO - error detected  YES - no error detected. But maybe errors nonetheless? More later . Goal: detect “errors” (e.g., flipped bits) in transmitted segment