Question

Every host in an IPv4 network has a 1-second resolution real-time clock with battery backup. Each host needs to generate up to 1000 unique identifiers per second. Assume that each host has a globally unique IPv4 address. Design a 50-bit globally unique ID for this purpose. After what period (in seconds) will the identifiers generated by a host wrap around?

Answer 1

Explanation:

• In a particular network IPv4 (32bits) can have total 2³² hosts given that each host can generate 1000 unique identifiers in 1 sec.
• 2³² hosts can generate 2³² x 1000 unique identifiers in 1 sec.
• 50 bit globally unique ID can have total 2⁵⁰ unique ids
• Wrap around time means in what time 2⁵⁰ unique ids will be used.  

Calculation:

\({2^{32}} \times 1000{\rm{\;packet\;or\;ids\;will\;used}} - - \to 1{\rm{sec}}\) 

\(1{\rm{\;packet\;or\;ids\;will\;used}} - - \to \frac{1}{{{2^{32}} \times 1000}}{\rm{secs}},{2^{50}}{\rm{packets\;will\;be\;used\;in}} - \to \frac{{{2^{50}}}}{{{2^{32}} \times 1000}}{\rm{\;}}\)\(\frac{{{2^{18}}}}{{1000}} = 262.14 = 262\)