Re: Re send-n for query optimisation

Jim Reid said:
>>>But the ENUM lookups don't have to be blocking,
>>>so why not let the client send an ENUM query after every digit (see  
>>>above
>>>for prefix/area code considerations)?
>> Because it's still load on the servers that would be worth reducing.
> I'm not sure that this load is ever likely to be significant in the  
> overall scheme of things Clive. Is there any hard data here or are we  
> all just working on guesses?

I don't have hard data, but I can give you some estimates.

Say 50 million telephone users in the UK. Assume each averages 1 hour of
calling per day, average call length 3 minutes, and a 25% failure rate of
call attempts (no answer, engaged, etc.). Finally, assume a busy-hour ratio
of 6:1.

That's then about 87,000 call attempts per *second*.

> How much query traffic could send-n  
> actually save as a proportion of the overall number of DNS lookups  
> that will be going on inside the NICC's private ENUM-like tree?

For calls in the UK, as Paul has shown, you need a lookup at 8 digits -
without send-N, that's therefore 4 lookups per call. Send-N will eliminate
2 of those. So that's 174,000 queries per second saved.

> I  
> would assume that these lookups would be passing through some sort of  
> resolving server, so there should be a Big Win for cache hits after  
> the initial "priming" query.

Let's assume caching gives you a 10:1 saving (I'm not at all clear it will
be anywhere near that good), so that reduces it to a saving of 17,000
queries per second.

-- 
Clive D.W. Feather  | Work:  <[email protected]>   | Tel:    +44 20 8495 6138
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