On Mon, Jun 19, 2017 at 1:37 PM, David R Huberman <[email protected]> wrote:
> Based on comments so far, most agree that a /48 should be SWIP'ed since it >> is routable on the internet, and since so far the majority seems to think >> that /56 is small enough to not require SWIP, this leaves 7 choices of /49 >> to /55 to set the limit for SWIP in the Draft. >> > > I think that when we consider SWIP boundaries, we should take into account > strictly technical considerations, and not arbitrary ones. I think the > argument for requiring a /48 or larger to be SWIPed is well-grounded in > network engineering practices. I'm not sure I understand the technical > argument for anything smaller than a /48 being mandatory. > Hi David, The obvious technical argument against Nibble "or larger" is that it encourages assignment on non-niblle boundaries. If /56 requires SWIP, the ISP has reason to assign /57 instead of /56. That makes IPv6 assignment as messy as IPv4. If instead /55 requires SWIP, the likely ISP default value becomes /56, a good nibble-boundary choice. A policy which starts requiring SWIP at Nibble+1 implicitly encourages the ISP to set their default assignment size at a nibble boundary which is well-grounded in network engineering practices So first and foremost it is technologically correct to set the SWIP boundary to start at "larger than Nibble" or "Nibble+1 or larger." Since "larger than /48" and "/47 or larger" are ruled out by /48's independent routability (also a technical consideration) and /64 is ruled out for preventing the intended end-user IPv6 routing ability (also a technical consideration), that leaves "larger than" /52, /56 and /60 as the only -technically reasonable- options. Regards, Bill Herrin -- William Herrin ................ [email protected] [email protected] Dirtside Systems ......... Web: <http://www.dirtside.com/>
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