[arin-ppml] ARIN-prop-132: ISP Sub-assignments Do Not Require Specific Customer Relationships

Benson Schliesser bensons at queuefull.net
Fri Feb 11 17:18:04 EST 2011

Hi, John.

The goal of ARIN-prop-132 is to clarify the definition of "customer" in, leaving the rest of the NRPM unchanged.  As written, I do not believe that it impact any other aspects of policy.

That said, answering your specific questions:

> 1) Will these suballocations be listed via SWIP/rWHOIS per the existing 
>  policy for customer assignments?  

Yes, based on my understanding of policy elsewhere in the NRPM.

> 2) Are there any minimum prefix size restrictions (since there is no 
>   routing relationship implied between the customer and the ISP which
>   provides aggregation)

No, based on my understanding of policy elsewhere in the NRPM.

However, it is an interesting question.  

I would posit that routing table growth is primarily a function of demand for connectivity.  ARIN policies limiting the shortest prefixes allocated may have acted as a multiplier against that demand, in terms of table growth.  However, if we assume that small reassignments were historically covered under an aggregate prefix advertised by a connectivity provider, then historical reassignment behavior (providing sub-assignments with connectivity services) would have acted to constrain table growth.  We might imagine that this policy proposal enables the movement of prefixes out from "underneath" their covering aggregate.  If this were unconstrained it might result in additional table growth in the DFZ.

Having acknowledged that possibility, my perspective is that ARIN policy does not limit the longest prefix size (smallest block) injected into the routing table.  Rather, operators limit longest prefix size in their individual networks.  As such, very small reassignments under this proposal might be filtered by various networks and could be unattractive to "customers".  Alternatively, if we do see significant table growth then the current practice of filtering, e.g. /24 or longer prefixes, might need to become more aggressive in time.  But I don't believe this is an aspect that must be addressed by ARIN policy.

As a side note, I think that federations of network providers and/or alternative technology approaches (LISP, etc) might be leveraged to enable further connectivity growth while constraining DFZ routes.  This policy opens the door to a number of interesting relationships that ISPs might explore.

> 3) Is there any prefix size maximum (e.g. could an organization holding 
>   a /8 have one customer receive the entire /8 as their assignment?)

No, based on my understanding of policy elsewhere in the NRPM.

Section indicates the maximum block that can be reassigned before ARIN approval is required, and proposal 132 doesn't affect this.  Proposal 132 does, however, limit ARIN from denying such reassignments based on the relationship between the customer and the ISP.

Per my comment above, it might be prudent to consider a proposal that allows larger blocks to be reassigned in order to encourage aggregation.  This is not currently part of proposal 132.


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