Currently, there are approximately 221 usable /8s: classes A (125), B (64) and C (32). (0.0.0.0/8, 10.0.0.0/8 and 127.0.0.0/8 aren't usable at this time.) Adding 16 /8s from class E space would increase this by 7%, and increase the unused address space with something like 20%.
However, it's almost certain that there are implementations out there that won't accept 224.0.0.0/4 as regular unicast address space. So if we want to be able to use class E space as such, it is imperative that we announce this a *very* long time in advance.
Two other possible uses:
It seems that there are now organizations who want/need more private address space than is available as per RFC 1918. Using class E space for this would make a lot of sense as this allows for a lot of private space without sacrificing usable unicast space.
In large networks, a lot of address space is used up and/or fragmented for point to point links and other infrastructure use. Using class E space for this could be a good compromise between using regular unicast space on the one hand or RFC 1918 space on the other hand.
Thoughts?
And is there a wg that deals / should deal with this issue?
Iljitsch van Beijnum
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