> Yeah, unfortunately, the growth is an issue and I don't think the above method
> can be guaranteed to work.  Short of the sending nodes being able to estimate
> the size of the overlay and hence extrapolate the expected number of entries
> in a via list and adjust the message size accordingly, we may have a problem.

IMHO, some statistics data from diagnostic procedure may be helpful for a 
sending node to estimate the possible hops for the request to be sent. For 
example, in Chord, the peer can periodically to send ping message to collect 
the hops needed to random keys which are located in difference scope in the 
circle. With this statistics data in mind, if a node wants to send a request 
keyed by key A, it can estimate the most accurate hops. More statistics data 
collected, more accurate number of the possible hops. OTOH, the peer also could 
record the maximum hop number, which is also be helpful to avoid future 
fragmentation. 



> Well, you are, however, potentially increasing the lookup latency.  The via
> list is probably the only reason that an intermediate node may be required to
> fragment the message.  An alternative might be for each node to maintain state
> about the previous hop instead of including a via list. 

My concern about the state maintaining mechanism for symmetric recursive is 
still security issues. If a malicious peer controls a couple of peers, it can 
let peer A sends a great number of requests which is destined to peer B. Upon 
receiving the request, the peer B won't give the response intentionally. In 
this case, all intermediate peers are full of state which could be only be 
cleared by timeout, so that the overlay will experience the DoS.  Am I missing 
something? 




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