Re: Download ENRP Namespace Data from Mentor Peer

Hi, Thomas,

The issue you discuss here is simply a race condition between ASAP and
ENRP. Since ASAP and ENRP are two separately protocols, there will be a
lot of race conditions that could occur in operation. And we realize
this situation from very beginning. Our strategy has been to allow the
discrepancies to occur and to rely on the auditing and re-sync
procedures to bring the name servers back to consistency. The reasoning
is simply - it would be too expensive to address the race conditions one
by one and it wouldn't make much sense either if we only address one
race condition without fixing the others... So my view is to stay with
the overall design strategy and let the auditing and re-sync procedures
to take care of the inconsistency.

regards,
-Qiaobing

Thomas Dreibholz wrote:
> 
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> Hi all,
> 
> when an ENRP server requests a namespace copy from a mentor peer by multiple
> PEER_NAME_TABLE_REQUEST / PEER_NAME_TABLE_RESPONSE cycles during startup, the
> mentor peer must also transmit PEER_NAME_UPDATES to the requesting name
> server. Otherwise, namespace inconsistency can be caused.
> 
> Example without PEER_NAME_UPDATE:
> 1. PEER_NAME_TABLE_RESPONSE with information about PE1.
> 2. PE1 updates its policy parameters or deregisters.
> 3. PEER_NAME_TABLE_REQUEST -> PEER_NAME_TABLE_RESPONSE with remaining parts of
> the namespace.
> => The requesting nameserver still has PE1's old data.
> 
> Example with PEER_NAME_UPDATE:
> 1. PEER_NAME_TABLE_RESPONSE with information about PE1.
> 2a. PE1 updates its policy parameters or deregisters.
> 2b. PEER_NAME_UPDATE for PE1.
> The new name server can update the PE1 entry or remove it.
> 3. PEER_NAME_TABLE_REQUEST -> PEER_NAME_TABLE_RESPONSE with remaining parts of
> the namespace.
> 
> Therefore, section 4.2.3 of the ENRP draft should be extended by requiring the
> mentor peer to send PEER_NAME_UPDATEs and the new nameserver to handle these
> messages.
> 
> Best regards
> - --
> =======================================================================
>  Dipl.-Inform. Thomas Dreibholz
> 
>  University of Essen,                            Room ES210
>  Inst. for Experimental Mathematics              Ellernstraße 29
>  Computer Networking Technology Group            D-45326 Essen/Germany
> - -----------------------------------------------------------------------
>  E-Mail:     [email protected]
>  Homepage:   http://www.exp-math.uni-essen.de/~dreibh
> =======================================================================
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