Re: [CGA-EXT] Next steps

Tony Cheneau <> Sun, 22 November 2009 22:13 UTC

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Date: Sun, 22 Nov 2009 23:13:13 +0100 (CET)
From: Tony Cheneau <>
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To: Roque Gagliano <>
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Subject: Re: [CGA-EXT] Next steps
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Hi Rogue,

>> I have no opinion to express yet. However, can you clarify your third
>> proposal ? You propose to modify RFC 3971 so a CPA message contains
>> both a Cert AND the corresponding CRL ? This is somehow an optimization of your first proposal ?
> What I though that could be theoretically possible is that when a host request a certificate, the router could send the certificate and the CRL in the Certification Path Advertisement Message. However, if you have a host that is connected for several hours, you will need to go back to fetch the new version of the CRL from time to time without needing to request the Cert because those are long living. For this reason, option 3 may not be such a good idea.
Sending an extra certificates every few hours to keep the protocol
"simple" (reusing the same CPS/CPA messages) does not sound too bad for
me. Moreover, you could multicast the message to the All-Node
address, so all the node on the link can know that a certificate is
still valid. What is the opinion of the other people on the list ?

>> Another advantage of solution 1 and 3 is that the node can verify the
>> validity of a prefix during the Stateless Address Autoconfiguraton
>> procedure, before assigning any addresses corresponding to this prefix to
>> an interface. This, IMHO, is an important feature.
> It is true that with option 2 you probably would need global unicast addresses to access the repositories that are outside of the local network while with option 1 you could send CRL request messages to the router using link local addresses. Is this what you meant?
Not exactly what I meant. I meant, you could send CPS/CRS message with the 
unspecified source address and receive a CPA/CRA from the router destined 
to the All-Nodes Multicast Address. Hence, you do not need to assign any 
addresses to our interfaces until you are sure that router's certificate 
has not been revoked.