[c-nsp] IP Accounting for IPv6

[Chris Mason]

> ...depending on the availability of Flexible Netflow on your hardware/IOS, you
> could use "permanent netflow caches" to simulate ip-accounting with flexible
> netflow.
> Permanent caches/cache entries are *not* exported to a collector by default
> and must be reset manually (or scripted). This feature is intended for long
> time caches residing on the devices - exactly what you're looking for.

Star answer, thank you! It seems to meet my requirements perfectly.
For anyone elses benefit, this seems to work (15.0(1)M6):

flow record IPv6-FLOW-RECORD
 match ipv6 destination address
 collect ipv6 source address
 collect counter bytes
 collect counter packets
!
flow monitor IPv6-MONITOR
 record IPv6-FLOW-RECORD
 cache type permanent
 cache entries 131072
!
interface Vlan199
 ipv6 flow monitor IPv6-MONITOR output
!

I can then manually capture the data and clear it as I need to!

Thanks,
Chris