Re: [v6ops] How do you solve 3GPP issue if neither operator nor handset supports PD?

otroan@employees.org Tue, 24 November 2020 12:40 UTC

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Subject: Re: [v6ops] How do you solve 3GPP issue if neither operator nor handset supports PD?
From: otroan@employees.org
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To: Philip Homburg <pch-ipv6-ietf-6@u-1.phicoh.com>
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Philip,

>> In the P2P Ethernet/3GPP case it says:
>> This prefix is not used on the link between us.
>> The prefix is dedicated to you, and I promise to install a route like:
>> ipv6 route <prefix> p2p-interface | interface, NH pointing at you.
>> You can if you like configure an address on the interface on the upstream lin
>> k,
>> as the router will forward traffic to anything in that prefix blindly.
>> (you aren't strictly doing SLAAC at that point though.)
> 
> In my experience, many true point-to-point links (such as ppp, but also
> tunnels) are like this.
> 
> The reason is that in theory you should do neighbor discovery even if a link
> has no L2 addresses. I found that many implementations just don't react
> to an NS or send any themselves.

That is correct for any implementation I have written.

> So all traffic is just sent to the other side of the link. I.e., the route
> could actually point to the link, but you can't really tell the difference.
> 
> In theory you could try to see if the router has an address on the link, but
> I never tried that experiment.
> 

And my point was that this is the desired behaviour in this case.
At least we should explore the consequences of not treating the nodes on each end as having a directly connected shared subnet (apart from fe80::/10) and what that does for address assignment/pd.

Best regards,
Ole