On Thu, Oct 9, 2014 at 1:55 PM, Richard Hicks <[email protected]> wrote: > On Thu, Oct 9, 2014 at 10:40 AM, William Herrin <[email protected]> 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 ................ [email protected] [email protected] Owner, Dirtside Systems ......... Web: <http://www.dirtside.com/> May I solve your unusual networking challenges?
