Most vendors have a TCAM that by default does IPv6 routing for netmasks <=64.
They have a separate TCAM (which is usually limited in size) that does routing for masks >64 and <=128. TCAMs are expensive and increase the BOM cost of routers. Storing routes with masks > 64 takes up twice the number of TCAM entries as the routes with masks <= 64. Since IPv6 is *supposed* to work with /64 masks, most vendors (usually the not-so-expensive-routers) provide a smaller TCAM for > /64 masks. Glen On Wed, Dec 28, 2011 at 6:40 PM, <[email protected]> wrote: >> On the other hand there's also the rule that IPv6 is classless and therefore >> routing on any prefix length must be supported, although for some >> implementations forwarding based on > /64 is somewhat less efficient. > > Can you please name names for the "somewhat less efficient" part? I've > seen this and similar claims several times, but the lack of specific > information is rather astounding. > > Steinar Haug, Nethelp consulting, [email protected] >
