doubt

Question

we find offset as data size/8 right?

 given  offset  is wrong, ..........am i right 

Comments

the values of offset given here are actual offset value, when you put these values in offset field of header than only you have to do scaling of 8 (i.e offset = actual_offset/8 )

---

Suppose a packet of length 1800 bytes with minimum header size enter a local area network with MTU (Maximum transfer unit ) of 500 bytes, then how many fragments will be generated from the packet and what is size of the payload of the last packet ?

 

in last packet why 360, why not 340..refer above solution

Answer 1

No everything in diagram is correct one....offset is = how many bytes of data is ahead of current packet...so for

1st one offset=0 correct

2nd packet offset=480....(480 is bytes )...so correct

3rd one=480+480=960 bytes so correct...

and for last one offset=480*3=1440 ...correct...

 

one simple trick i use is ....given data is cut into small pieces of 8 bit that is 1 bytes and then we put it in packet......given in diagram its already in bytes...so no need of dividing by 8.....

Comments

https://gateoverflow.in/2062/gate2014-3-28?show=2062#q2062

here why  we divided it by 8 

Answer 2

1st fragment offset=0 (always)

2nd   fragment offset=(prev. fragment  offset + prev. fragment data part/8)=0+480/8=60

similarly,, 3rd   fragment offset=(prev. fragment  offset + prev. fragment data part/8)=60+480/8=120

4th   fragment offset=(prev. fragment  offset + prev. fragment data part/8)=120+480/8=180