in Computer Networks edited by
3,276 views
0 votes
0 votes
Suppose that a message 1001 1100 1010 0011 is transmitted using Internet Checksum
(4-bit word). What is the value of the checksum?
in Computer Networks edited by
3.3k views

2 Answers

17 votes
17 votes
As we are asked for 4-bit checksum, so divide the data into 4 bit words and add all.

1001 + 1100 + 1010 + 0011 = 100010

We want 4-bit checksum, bring 10 down and so add

0010 + 10 = 0100

And checksum will be the complement of 0100 which is 1011 .
edited by
by

4 Comments

You added four 4-bit words, how it produced a 6-bit output?
0
0
1001 + 1100 + 1010 + 0011

In decimal we can write this as,  9 + 12 + 10 + 3 = 34

Converting 34 to binary we get 100010
0
0
why only two bits brought down?
0
0
Because we want 4-bit checksum. but, 2-bits are extra.
0
0
3 votes
3 votes
Add these numbers 1001+1100+1010+0011 you will get 0010 and a carry of 10 now add carry also in 0010 so 0010+10 =0100 now performs 1’s complement. you will get result as 1011 which is the required answer.

Related questions