Re: [v6ops] Fwd: New Version Notification for draft-linkova-v6ops-ipmaclimi-00.txt

[David Farmer <[e-mail]>]

On Mon, Nov 7, 2022 at 7:25 PM Jen Linkova <[e-mail]> wrote:

> Hello,
>
> As I've come across some rather nasty failure scenarios, affecting
> both IPv6-only and dual-stack deployments, I think it might be useful
> to re-emphasize RFC7934 and provide some recommendations to vendors.
>
> This is a rather raw -00, the text is very brief and unpolished, it
> will be definitely expanded and improved, should the group agree that
> this is a problem worth solving.
>
> Feedback/comments are appreciated indeed!
> Thanks!


A different anecdote of a corollary problem;

I have a bunch of $1M router line cards that were default tested for 2000
IPv4 ARP entries and only 256 IPv6 ND entries. I had to have the vendor
test a custom profile that was at least a little more realistic. I think
the draft should say something about the typical IPv6-only or even Dual
stack network will need significantly more, probably multiple times, the
IPv6 ND entries than the IPv4 Arp entries of a comparable IPv4-only
network. A tested ND scale that is 1/4 the tested ARP scale is
completely unacceptable these days; that example is probably at least
backward; there should probably be at least 4 times the ND scale as the ARP
scale.

The suggestion for LRU (least-recently-used) for the management of the list
is also a relevant and important suggestion.

While I agree this is not exclusively a problem with SLAAC, the problem
exists for manual configuration and DHCPv6 as well, at least to one extent
or another. However, at least in theory, with DHCPv6 the network can
prevent a host from configuring an unlimited number of addresses. It is my
understanding that this is in fact the reason that Android doesn't support
DHCPv6 on mobile devices.

So, using DHCPv6 doesn't eliminate the issue, but with DHCPv6 there can be
bounds enforced by the network; this clearly comes with its own set of
costs and limitations and contrives at least part of the intent of RFC
7934. But there can be differences between DHCPv6 and SLAAC.

Thanks

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David Farmer               Email:[e-mail]
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