On 01/01/2016 06:04, Jared Mauch wrote: ... > The reason we (as an operator) can’t use BCP-38 is the vendor hardware can’t do it at line-rate and the performance hit is too much to sustain. That seems worth a bit more discussion. I'd always naively assumed that BCP38 was scalable since all it appears to need is a prefix match, and routers are very good at matching prefixes; it's just that they don't normally match the source prefix. Could some router-vendor person comment on this? There's another issue here, though. BCP-38 and uRPF are also a potential cause of connectivity problems: https://tools.ietf.org/html/draft-ietf-6man-multi-homed-host Brian