IPv6 address usage (was: Re: RFC4941bis: consequences of many addresses for the network)

[Fernando Gont <[e-mail]>]

On 24/1/20 14:20, Michael Richardson wrote:
> 
> Fernando Gont <[e-mail]> wrote:
>      > Nodes can configure as many addresses as they please. If you want the
>      > network to enforce policy, then you should probably be using DHCPv6 --
>      > as many enterprises do.
> 
> I think that the too many addresses is more an issue on
> conference/coffee-shop networks rather than in an enterprise environment.

Why should it? The only reason why the number of addresses could be a 
concern in that scenario is:

1) MLD-snooping
2) Neighbor Cache entries

For the former, I guess one can resort to broadcasting the frames. For 
the later. Well, you need to be smart at managing the neighbor cache, 
anyway.




> I think that it is reasonable to establish an upper limit (8? 16?) of number
> of entries per MAC address in a border router in those environments.

HOw would that go along with RFC7834/BCP204?


> (Are there such controls today in APs/routers?)

I'm aware there are things like that for devices implementing first home 
security.

Now, given that rfc4941 is a deployed reality, trying to enforce a limit 
that's so close to the number of addresses that a host might use -- as 
per rfc4941 -- doesn't seem to be a good idea (actually, it's asking for 
breakage).


> This is exactly the place where temporary addresses make the most sense.
> The only reason it isn't a problem now is because (a) lack of IPv6,
> (b) most coffee-shop visits are shorter than lifetime.

Where, specificallt, would you expect temporary addresses to be causing 
trouble?

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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