Loopback Address 127.0.0.0

[ugaaf1000]

As we know that 127.0.0.1 is Loop Back series. IANA has dedicated this whole series for Loop Back. Question is why IANA Dedicates this Whole range of IP address only for one purpose...that is Loop Back . we already know that this IP range has 16 Billion Host addresses. so whole range carries 16 Billion is only Loop Back purpose. it means we are loosing 1 complete range of Class A Network......!!!

Ugaaf

[rais]

Just a minor correction, it's about 16 Million. I think IANA thought it might be helpful to reserve this large space for future use.

Thanks.

[tbaranski]

Back when addressing was done classfully (pre-CIDR), the use of all-ones and all-zeroes subnets was discouraged for reasons discussed here: http://www.cisco.com/warp/public/105/40.html

Hence, IANA reserved the numerically lowest and numerically highest address block of each "class". 127/8 is the highest block in Class A address space, 191.255.0.0/16 is the highest in Class B, and so forth (see RFC 3330). So 127/8 would have been reserved anyway -- loopback or not -- and presumably it was decided to make one of these already-reserved blocks the loopback block rather than reserving an additional block.