UDP and TCP use 1’s complement for their checksums to detect errors. Suppose you have  the following 8-bit bytes: 11011001, 01010010, 11001010, 10100100 and 01011001.  A. What is the 1’s complement of the sum of these 8-bit bytes? Show all the details of your work.  B. Why do UDP and TCP take the 1’s complement of the sum as their checksum? That is, what do  UDP and TCP not simply use the sum of these bytes as checksum?  C. With the 1’s complement scheme, how does the receiver detect errors?  D. With this checksum scheme, is it possible that any l-bit error will go undetected? How about a  two-bit error? Explain your answer.

Suppose a file of 10,000 bytes is to be sent over a line at 2400 bps. A. Calculate the overhead in bits and time in using asynchronous communication. Assume one start bit and a stop element of length one bit, and 8 bits to send the byte itself for each character. The 8-bit character consists of all data bits, with no parity bit. B. Calculate the overhead in bits and time using synchronous communication. Assume that the data are sent in frames. Each frame consists of 1000 characters = 8000 bits and an overhead of 48 control bits per frame. C. What would the answers to parts (a) and (b) be for a file of 100,000 characters?

Write a general code for a polar RZ line coding scheme. assigned decimal number = 248 This number is to be converted to line code. And, bit duration = 9 µs Specifications: 1. Line Coding Scheme: Polar return to zero 2. Binary Code to be Generated: Assigned decimal number 248 3. Duration of Each Bit: 9 µs

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A block of bits with n rows and k columns uses horizontal and vertical parity bits for error detection. Suppose that exactly 4 bits are inverted due to transmission errors. Drive a mathematical expression of n and k for the total number of different cases where these 4 error bits will be undetected. Show each important step of your derivation. (Hint: the error bits will be undetected if all the parity bits computed from the block remain unchanged.)

Internet Checksum. Consider the six sixteen bit numbers: 10110101 01000110 01001001 01101011 10110100 01000110 01001001 01101101 10110101 01010110 01011010 01101111 Compute the Internet Checksum field value of these six words (each word has sixteen bits) Enter the 2 bytes each as an 8-bit number with only O's and 1's, and make a single blank space between the two 8-bit numbers (e.g., 01010101 00101000). [Note: you must use bitwise XOR logic function and don't use 2's or 1's complement] Not quite. This answer is incorrect.

Suppose a file of 10,000 bytes is to be sent over a line at 2400 bps. A. Calculate the overhead in bits and time in using asynchronous communication. Assume one start bit and a stop element of length one bit, and 8 bits to send the byte itself for each character. The 8-bit character consists of all data bits, with no parity bit. B. Calculate the overhead in bits and time using synchronous communication. Assume that the data are sent in frames. Each frame consists of 1000 characters = 8000 bits and an overhead of 48 control bits per frame. C. What would the answers to parts (a) and (b) be for a file of 100,000 characters?

How may the interval between bytes be different in asynchronous transmissions?