Over-utilisation of v6 neighbour slots

[Lorenzo Colitti]

On Tue, Oct 29, 2013 at 6:53 AM, Phil Mayers <p.mayers at imperial.ac.uk>wrote:

> I wanted to follow up on this. Some folks from Cisco kindly contacted me
> off-list, and correctly guessed that a large number of the IPv6 neighbour
> entries were in state "STALE", and pointed me to the relatively new:
>
>
>   ipv6 nd cache expire <seconds>
>
> ...interface-level command. This wasn't in the IOS train we were running
> until relatively recently, so I hadn't seen it before.
>

I wonder what the designers were thinking when they did the original
implementation. Without this option, a box with enough client churn could
run out of neighbour cache entries even if all the clients are perfectly
behaved.

Perhaps they didn't think of it because it doesn't happen in IPv4 due to a)
much fewer addresses on a given box due to scarcity and b) ARP has timeouts.
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