On Tue, Jan 17, 2017 at 6:06 PM, Sander Steffann <sander@steffann.nl> wrote:
One thing that comes to mind is that it seems that some routers only have limited space in their routing tables for prefixes longer than a /64. If you would configure a /127 on the link but push the /64 to the routing table then you might both avoid ND Cache exhaustion and avoid the limitations on longer-than-/64 prefixes.
Hi Sander, IIRC, the problem was that some routers could only fit the first 64 bits in the TCAM so routes longer than /64 fell out of the fast path. That was about half a decade ago. No idea if anything modern still suffers from this. That would impact every route in Matthew's proposed solution: the loopbacks from the infrastructure /64 and the /127's from otherwise unpopulated /64's. Because programmatically those /64's don't have one prefix, they have two: the /127 for the link and the implicit null route for everything else. The router has to honor the implicit null route so it can't aggregate the /127 to /64 and keep it in the fast path. Regards, Bill Herrin -- William Herrin ................ herrin@dirtside.com bill@herrin.us Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/>