Re: Comment on VIA_RVS parameter - 5204 & 06 -bis

Miika Komu <[email protected]> Tue, 27 Sep 2016 11:58:18 +0300
Newsgroups gmane.ietf.hipsec,gmane.ietf.hip
Organization Ericsson AB
Message-ID <[email protected]>
Hi,

On 09/27/2016 03:56 AM, Robert Moskowitz wrote:
>
>
> On 09/26/2016 09:08 AM, Miika Komu wrote:
>> Hi,
>>
>> On 09/16/2016 02:45 PM, Robert Moskowitz wrote:
>>>
>>>
>>> On 09/16/2016 06:57 AM, Tom Henderson wrote:
>>>>
>>>>
>>>>
>>>> On Thu, 15 Sep 2016, Robert Moskowitz wrote:
>>>>
>>>>> 5206-bis specifies how to user RVS for the 'double-jump' mobility
>>>>> problem.
>>>>>
>>>>> 3.2.3 1) says:
>>>>>
>>>>> 1. The mobile host sending an UPDATE to the peer, and not receiving
>>>>> an ACK, MAY resend the UPDATE to a rendezvous server (RVS) of the
>>>>> peer, if such a server is known.
>>>>>
>>>>> But it DOES know there is an RVS IF the I1 had FROM and RVS_HMAC
>>>>> parameters and it had created a VIA_RVS parameter to send in the R1.
>>>>
>>>> Yes, but the responder may not know the initiator's RVS even if the
>>>> the responder's RVS was used, and it also may be the case that neither
>>>> host's RVS was involved in the session setup.
>>>
>>> I see now.  As currently speced, R has no way of learning I's RVS. The
>>> 'easy' way to fix this is for I to include a VIA_RVS in the I2 packet
>>> for mobility support.
>>>
>>> "If you every want to get back to me, I can always be reached at this
>>> number".
>>
>> do you actually need the initiator's RVS for double jump? I think the
>> responder's RVS is enough.
>
> Then the Initiator's UPDATE must be successful before the Responder can
> perform its UPDATE successfully.  This way they can operate in parallel.

I see, you really want to avoid packets being dropped.

>>>>> This VIA_RVS provides the knowledge and locator of the peer's RVS.
>>>>>
>>>>> In fact an aggressive mobility UPDATE would be sent simultaneously to
>>>>> the host and its RVS.  If the host had not moved itself, it gets both
>>>>> and drops the one from the RVS.
>>>>
>>>> I believe that Baris Boyvat on the InfraHIP project was looking a
>>>> while back at such an approach to fast mobility; it was called
>>>> 'shotgun' approach to mobility and multihoming (try all candidates
>>>> simultaneously), if I remember correctly.
>>
>> Yes, the idea was to send I1 (or UPDATE) through all the available
>> address pairs, but I think the idea is now achieved in a more
>> controlled way in draft-ietf-hip-native-nat-traversal-13
>
> I will look at that.  But what if there is no NATs to traverse? That
> there are 2+ interfaces, all native IPv6?
>
> But I will review nat-traversal.

Basically the nat-traversal draft is about connectivity checks (that 
traverse NATs), nothing much IPv4 specific there. Feedback is still welcome.

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