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[AfriNIC-rpd] Updated Version of the "IPv4 Soft Landing Policy" now Available Online

David Conrad drc at
Tue May 3 14:15:12 UTC 2011


On May 3, 2011, at 6:10 AM, Leo Vegoda wrote:
>> Why would you give someone address space if its not for routing? 
> In the past I have seen cases where people wanted unique addresses for numbering private networks, VPNs and so on.

Yep.  It has been the case that other RIRs have indeed allocated longer than /24 prefixes for this purpose.  However, I don't believe that is the rationale for this policy (nor, IMHO, should it be -- private addressing should no longer be used as a justification for IPv4 space).

The implication of allocating longer than /24 PI is that a receiver of that address will face increased connectivity challenges. Folks who receive longer than /24s will need to identify people who filter on /24 (or shorter) and individually convince them to relax their filters (which may require the longer-than-/24 announcer to pay the filterer).

Further, while not everyone filters on /24 today, as the routing table grows in the face of IPv4 market activity and IPv6 deployment, it is almost certain that ISPs will start filtering so their routers don't run out of memory and fall over.  Historically, the simplest/easiest filters to apply were prefix length filters (since long prefixes affect fewer end sites, can cause more routing system thrash, and are less likely to house sites the filtering ISP's customers care about).

This outcome would be more probable if the allocation of /27 by AfriNIC was taken by other RIRs and new market entrants as a precedence and defined the new maximum prefix length.  Looking at the remaining address pools today (from, there are a total of 10.9 million /27s (of which, 2.5M are in the AfriNIC region).  What percentage of those would need to be allocated to cause routers to fall over (and hence, result in prefix-length filters)?

> IP addresses are for IP networks. Whether you and I will ever communicate with them is not important when the assignment criteria are needs based.

Well, when assignment criteria are _exclusively_ needs based. If /27 becomes the new maximum prefix length, I suspect it would be ... nice if the recipient were made to fully understand the implications of trying to announce that prefix ("Death of the Internet predicted, MPEG unavailable due to routing collapse").


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