On Thu, Oct 9, 2014 at 1:55 PM, Richard Hicks <richard.hicks@gmail.com> wrote:
On Thu, Oct 9, 2014 at 10:40 AM, William Herrin <bill@herrin.us> wrote:
"Regardless of the number of hosts on an individual LAN or WAN segment, every multi-access network (non-point-to-point) requires at least one /64 prefix."
But using /64s on WAN links invites needless problems with neighbor discovery when an attacker decides to send one ping each to half a million adresses all of which happen to land on that WAN link.
The BCOP specfically addresses this in 4b: " b. Point-to-point links should be allocated a /64 and configured with a /126 or /127"
It says, effectively, that a WAN link involving 3 or 4 routers (a common redundancy design) should use a /64. I think that's nuts. It creates a needlessly wide attack surface. Use a /124 for that. And if our subnets should be on nibble boundaries, /126 and /127 on ptp links aren't so wise either. Use a /124 for that too. -Bill -- William Herrin ................ herrin@dirtside.com bill@herrin.us Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/> May I solve your unusual networking challenges?