#tanenbaum

Question

A router is blasting out IP packets whose total length (data plus header) is1,024 bytes. Assuming that packets live for 10 sec, what is the maximum data line speed the router can operate at without danger or cycling through the IP datagram ID number space?

my solution:

Packet length = 1,024 bytes

1 packet will contain 1024 byte

then 2^16 packet will contain= 2^16 * 1024 byte= 2^16 *2^10 * 2^3  bits= 2^29 bits.= 512 mb

time =10 sec

bandwith= 512mb/ 10 sec 

                =51.2 mbps……...….……….but answer given is 53.68mbpsi dont know where i am wrong?

 

Comments

The IP datagram ID number space is 216= 65535
Packet lifetime = 10 seconds
Therefore, a maximum of 65535 packets may be sent in 10 seconds. If any more packets were to be sent within the 10 seconds, there would be multiple live packets with the same ID.
floor(65535/10) = 6553 packets/sec

The maximum line speed @ 1024 bytes/packet is:
1024 bytes/packet * 6553 packets/sec * 8 bits/byte = 53,682,176 bps (~ 53.7 Mbps)

 

Found this explanation, let me know if you need clarification

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in the above solution which you have provided, for conversion of bps to mbps  it is just dividing by 10^6(1 mb= 10^6 b) but in my solution, i  am dividing by 2^20(1 mb= 2^20 b).

dont know which method is correct.

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When bandwidth you should take 10 power