IPv6 over unidirectional links?
Gorry Fairhurst <firstname.lastname@example.org> Thu, 16 July 2009 08:00 UTC
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Date: Thu, 16 Jul 2009 08:33:35 +0100
From: Gorry Fairhurst <email@example.com>
Organization: The University of Aberdeen is a charity registered in Scotland, No SC013683.
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Subject: IPv6 over unidirectional links?
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Here is an off-list thread that Bernhard introduced on the use of IPv6 autoconfiguration with unidirectional links. More thoughts would be welcome. Gorry >>> Bernhard Collini-Nocker wrote: >>>> >>>> Dear Gorry, >>>> >>>> I´d like to add a point that I have raised a few times in the >>>> past years without too much feedback/support: there is in my >>>> opinion an issue with unidirectional >>>> links and IPv6 (neighbourhood discovery) addressing of >>>> rx-only network adapters. >>>> >>>> --Bernhard >> >> Hi Gorry, >> >> Gorry Fairhurst schrieb: >>> >>> Here is what I recall: this is to do with IPv6 autoconf when >>> you can't do DAD, NUD, etc. Is that right? >>> >> right, it is all kind of tricky when the link is not per se >> bidirectional. The impacts may in many cases be neglectible, >> but there may corner cases. >>> >>> I don't recall what you proposed to do in this case though, >>> because on a unidirectional link, I'd expect the sender ND >>> cache to be pre-populated with IPv6 addresses (since ND/SEND >>> could not be used to query this). So is it right that the remote >>> endpoints just rely on RA's to find their own on-net prefix >>> and configure their IPv6 addresses without being able to >>> validate their uniqueness (is this an issue though? >>> - in receive-only applications, the endpoints never send >>> with this prefix anyway). Maybe I have misunderstood? >> >> Well, my concern was/is that in an environment, where >> destination IP addresses of rx-only devices are non-unique, >> but are used as identifiers this might cause problems. >> Also, some mechanisms of IPv6 might fail in what case such an >> interface might be unavailable? Actually there are both >> operational and conceptual aspects in that problematic. >>> >>> If we need work in this space, we'd need to decide if this >>> were a 6man or ipdvb issue - but there is certainly no harm >>> discussing this in ipdvb. >> >> I guess so. >> >> --Bernhard >>
- IPv6 over unidirectional links? Gorry Fairhurst