[deepspace] Re: A possible TIPTOP deployment question: traffic crossing heterogeneous network boundaries

[Tony Li <[e-mail]>]

Given the challenges involved, I suspect it very likely that direct communications will never be allowed and that application relays (e.g. mail gateways) are always relevant.  Thus, there’s really no point in solving the generalized problem.

Regards,
Tony


> On Jun 30, 2026, at 1:27 AM, Alexander PELOV - alexander.pelov at imt-atlantique.fr <[e-mail]> wrote:
> 
> Hi Michael, all,
> 
> I think prefixes solve part of the question, but not all of it.
> 
> How is a host supposed to know that its communication will traverse an interplanetary hop? 
> For example, imagine someone working remotely from Olympus Mons, on Mars, connecting through a company VPN to read email.
> 
> The mail client may or may not know that the path involves an RTT of around 40 minutes.
> If it does know, it may be able to adjust its behavior accordingly. If it does not, some timers may simply keep expiring.
> 
> One could imagine the VPN itself performing traffic conditioning or policy enforcement, and sending ICMPv6-SEC messages to the host to indicate that the other side is not 40 ms away.
> Depending on the architecture, the VPN client could also be the component that receives and interprets such indications.
> 
> Of course, this is only one example. My broader point is that there may need to be some mechanism for the network to inform hosts that the path, or part of the path, has unusual constraints.
> 
> Cheers,
> Alexander
> 
> 
> 
> 
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> 
>> On 28 Jun 2026, at 19:45, Michael Richardson <[e-mail]> wrote:
>> 
>> 
>> RJ A <[e-mail]> wrote:
>>> In the current threat environment, it is clear that it would be unwise
>>> to change behavior in reaction to an unauthenticated control message,
>>> such as an ICMP message.  Authorization is also an issue here, albeit
>>> one that IETF has never really sorted out.
>> 
>> Agreed strongly.
>> 
>> It's a kind of authorization that many mechanisms would benefit from, but
>> seems impossible to ever get to.
>> {Had it been there from the beginning, I suspect that IP would have not succeeded...}
>> 
>> (This is a reason why prefix per celestial body is useful; if destination is
>> "non-local", then go for better defaults. )
>> 
>> 
>> --
>> Michael Richardson <[e-mail]>   . o O ( IPv6 IøT consulting )
>>           Sandelman Software Works Inc, Ottawa and Worldwide
>> 
>> **       My working hours and your working hours may be different.         **
>> ** Please do not feel obligated to reply outside your normal working hours **
>> 
>> 
>> 
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