On Wed, 2003-11-19 at 17:21, Ian Clarke wrote:
> Toad wrote:
> 
> > Is there any reason not to keep the backoff data when a node is dropped
> > from the routing table?
> 
> Provided we delete it sometime, probably not.
> 

It seems to me that there is some reasonable maximum backoff period.

For instance, suppose there are N total nodes that ever contact
mine during any given hour.  And suppose that Q rejected queries 
per minute has a "small" effect on my performance and on my network
bandwidth, and maybe on routing performance.

Then, Q/N rejected queries per minute per node has only a small 
effect, and one node need not reduce its queries per minute below 
Q/N.

Therefore, N/Q minutes per query is the longest reasonable backoff
for any given node in the pool of N which contact mine.  The number
specifies the longest backoff interval nodes contacting mine should 
use, not the longest interval I will use in contacting other nodes.

Perhaps M/Q should be a configurable parameter and part of the 
node reference data.  Or, perhaps the implementation should make 
it dynamically adjustable by including it in the QR message.

The requesting node might also want to calculate a maximum reasonable
backoff period for all of the nodes it queries, on the basis of its
own output bandwidth and the number of nodes it contacts regularly.
This limit would ensure that rejected queries would consume a small
amount of the requesting node's output bandwidth.

For any given peer, the requesting node will backoff at most enough
to ensure that neither its own performance nor its peer's performance
nor routing performance in general is affected by rejected query 
traffic.

This number should be kept with the node reference, not in the
routing table, so that nodes which leave the routing table and
return quickly do not circumvent the backoff.  Since backoffs are
capped, there is no need for a separate mechanism to remove stale
values.

-- Ed Huff

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