Assignment 3 – Transport Layer

1. Computing an Internet checksum.

Consider the two 16-bit words (shown in binary) below. Recall that to compute the Internet checksum of a set of 16-bit words, we compute the one's complement sum

[http://mathforum.org/library/drmath/view/54379.html] of the two words. That is, we add the two numbers together, making sure that any carry into the 17th bit of this initial sum is added back into the

1's place of the resulting sum); we then take the one's complement of the result.

o Compute the Internet checksum value for these two 16-bit words:

o With the checksum value (1’s complement) how does receiver detect errors?

00100000 10010001 this binary number is 8337 decimal (base 10)

11101010 11010010 this binary number is 60114 decimal (base 10)