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On 02/19/2011 06:09 PM, Eric Rescorla wrote:
> 
> On Feb 19, 2011, at 3:53 PM, Marc Petit-Huguenin wrote:
> 
> On 02/13/2011 05:04 PM, Bruce Lowekamp wrote:
>>>> Marc,
>>>>
>>>> I think there's an underlying issue here of whether it's important to
>>>> - use the same "physical" connection between two physical nodes that
>>>> are both acting as multiple virtual nodes for all pairs of
>>>> connectivity between them
>>>> AND
>>>> - differentiate on the receipt of a message what pair of virtual nodes
>>>> A'->B' the original sender believed the message was going between.
>>>>
>>>> I'm not immediately convinced that this is a useful property for the
>>>> routing system, as if each physical node is merging the virtual nodes'
>>>> routing tables and forwarding to the closest match, I don't think it's
>>>> necessary for reliable routing.  However, if you have a pointer to a
>>>> description of why this would be useful, I'd be very interested in
>>>> reading it.
>>>>
>>>> With that said, my current opinion is that what you want to accomplish
>>>> can and should be accomplished through a new routing algorithm.
>>>> However, I think we should move to incorporate the new SignerIdentity
>>>> into the base draft and probably handle the IceExtension as a new
>>>> draft.  But both should probably get a thread of their own so they
>>>> have more eyes.
> 
> I spent more time on this problem(s) (the fact that the information on a
> specific subject are scattered all over the I-D does not help, for sure), and 
> I
> am now less sure that there is a need for this changes.  Let's take the issues
> one by one:
> 
> 1. Connections sharing:  I am still running some simulations and so far I do 
> not
> have an definitive answer, so let forget about this for now.  Hopefully it 
> could
> be done as an extension, as you suggested.
> 
> 2. Knowing the Node-ID of the sender of an end-to-end message, when multiple
> Node-IDs are used in the certificate:
> 
> - If the message is a request and traversed at least one peer, then the sender
> Node-ID will be the first Node-ID in the via list.
> 
>> Regrettably, this is not always true due to via list compression. If you 
>> want to know
>> this, we should add an extension to the signature.
> 
> 
> - If the message is a request that was sent over a direct connection, then the
> sender Node-ID is the Node-ID associated with the connection - see (3).
> 
> - If the message is an answer, then the sender Node-ID is the same Node-ID 
> that
> was used to send the matching request.  An implementation had to store it for
> the end-to-end retransmission, so it is retrievable from the transaction-id.
> 
>> I fear that this is not true as well, since you can send to a resource-id.

OK, so the Signature extension is mandatory to use multiple Node-IDs in
certificates.  But the IceExtension still seems useless, as, thanks to the
Signature extension, we always know the Node-Id on each side of the Attach.

Also a client joining the overlay using a certificate with multiple Node-IDs,
using the procedure in the second bullet of section 3.2.1 will still have 
problems.

> 
>> -Ekr
> 
> 3. Knowing the Node-ID of the sender of a message on a direct connection, when
> multiple Node-IDs are used in the certificate:
> 
> - Because direct connections are established by Attach, the Node-ID of the
> sender of a message on a direct connection is also the Node-ID of the sender 
> of
> the Attach message (request or answer) that was used to establish the direct
> connection - see (2).
> 
> Now there is one case that does not work: a client with a certificate with
> multiple Node-IDs.  Because a client connects directly to a bootstrap peer
> (without Attach), the bootstrap node has no way to know which Node-ID to 
> choose
> on the certificate.  When the Attach to the admitting peer will be sent by the
> client, the bootstrap peer will not be able to know what Node-ID to add in the
> via list, and so will not be able to route back the answer.  And neither a new
> SignerIdentity or IceExtension can help in this case.
> 
> So because it is not possible to join an overlay with a certificate containing
> multiple Node-IDs, the only way it could work would be to join with a
> certificate containing one Node-ID then after the Attach to the admitting peer
> switch to a certificate with multiple Node-IDs.  Was that the intent?

- -- 
Marc Petit-Huguenin
Personal email: [email protected]
Professional email: [email protected]
Blog: http://blog.marc.petit-huguenin.org
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