Re: [LARTC] Strategy for about 200 part-time users

[Ed Wildgoose <lists@wildgooses.com>]

>But I find it awkward, for our purposes, the way rate and ceil seem to
>work.  If we theoretically have 200 clients, and all 200 are on, then
>we can set rate for 1/200 of the total ... in our case only about 10
>kilobits per user.  They CAN borrow up to ceil, yes.  But since we are
>REALLY busy, we can't really do much to give one client more than
>another.
>  
>

Hey, I just read the docs, I don't have any experience of using this.  
BUT, there appears to be a priority option (it's not called priority, 
but I don't have the docs in front of me) on the HTB qdisc which seems 
to let you bias the squabble towards certain users and away from 
others.  I vaguely recall that it might be that the excess gets divided 
as a ratio of the priorities?

>However, if we KNOW only 50 are on right now, then we can give each of
>those a rate of 1/50, guaranteed.  We can set ceil a little
>differently.  And if we have bandwidth hogs, we can adjust things so
>it is fairer for all.
>
>Suppose we have invited 200 guests for dessert.  So we make 200 tarts
>to be sure everyone gets one.  But only 50 guests show up.  So they
>eat their own tart, and then fight over the other 150 tarts.
>
>What if you could look at the total number of guests before they enter
>the dining room, make a quick assessment, and put two or three tarts
>on each plate instead of one.  They still might squabble a bit over
>the remaining tarts, but not as much of a free-for-all as before.
>  
>

Hmm, perhaps I'm being stupid, but those two situations seem to be 
identical to me?  I can't see the difference between 1 "tart", and a 
1/50 share of the remaining 150 tarts, or starting with 1/50 of 200 
tarts...?

Also, you appear to be more interested in priortising based on the 
*type* of traffic.  So that appears to be more logically at the top of 
your tree.  Its only like this that you can limit the P2P people I 
think.  Otherwise all you can say is that each P2P user can use their 
full allocation of bandwidth to download junk.  However, if you put P2P 
at the top and limit it to 20% of total, then each user will be able to 
use *up to* their full quota, but if there are lots of P2P users, then 
each may not even be able to reach that level, and so will find they are 
throttled back below even their personal download quota.  This appears 
to be what you are after?


>This is a really interesting idea ... if we can keep our accounting
>separate then it WOULD open up more possibilities.  Maybe someone can
>point me in the direction of IP traffic accounting that we could use
>separate from the tc.
>  
>

I thought that there were accounting logs on all iptables chains.  There 
is also an accounting option in iptables I seem to remember (check man 
pages).  Perhaps there are other options involving a user space queue 
which doesn't actually queue, but counts stuff...  I'm sure there are 
other options as well

>>For example, you could setup the rules with the class of traffic at the 
>>top and the users underneath, eg top level is "P2P", "bulk", 
>>"interactive", and under each is a user class (or SFQ, etc).  Now you 
>>could limit the P2P to be only 1/3 of total bandwidth, which is then 
>>fought over by the users (each will get a fraction depending on how many 
>>others are using it, not how many classes you have).  Perhaps for the 
>>other classes even SFQ will be enough? 
>>    
>>
>
>I think I can see that ... if we don't have to put each customer into
>one (or two or three) different buckets.  If we could even put groups
>of customers into buckets together, that might be good.  But again, it
>seems like it would be handy to be able to dynamically change bucket
>sizes and whose packets go through them.
>  
>

I think this method will make that easier?  Remember that each customer 
will turn up multiple times now, ie for each type of traffic.  You can 
more easily tune the buckets determining the amount of each sort of 
traffic, eg turning up P2P in the evening, and down in the day simply by 
adjusting the single top bucket (not each individual one).

Good luck

Ed W
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