Shorewall Guy wrote:

>  > The next thing you need to remember is that your effective link speed
>>  may well be very different to the sync speed of your modem/whatever.
>>  At work we have the luxury, at a cost I might add, of an uncontended
>>  and unlimited service (we do hosting) which measn we know exactly
>>  what we can shove up the wire. At home, I'm on an ADSL service where
>>  there is no guaranteed speed - the actual throughput will be lower
>>  when others are using their connections, so I have to guess at what
>>  max speeds (down and up) will mostly avoid me hitting restrictions
>>  due to contention in my ISPs backhaul. In practice, I set my up and
>>  down speed limits somewhat below the sync speed of the ADSL modem to
>>  allow for this contention.
>>
>
>The description of IN-BANDWIDTH in the Shorewall TC doc includes a
>procedure for attempting to find an appropriate setting for that parameter.

A procedure that, in the general case, only gives a valid value for 
that specific point in time. What I was trying to get across, is that 
on most 'consumer' connections and most business ones as well unless 
you pay a LOT for your bandwidth, there is no simple limit to set as 
it varies depending on what other traffic (other users) is sharing 
the backhaul.

Over here in the UK, there is a big stink that's been festering for a 
couple of years about actual traffic rates - both on ADSL and cable. 
Most of the ISPs are run by the marketing types who think it makes 
sense to advertise a service as "up to 8M" and "unlimited" while 
hiding behind the (very) small print - and so far our (non)regulator 
OfCom has failed to do anything useful about it. There's now a 
voluntary code of conduct that says ISPs should tell prospective new 
customers both the data rates they can reasonably expect AND what the 
usage limits actually are. I don't expect this to help as the ISPs 
will probably still talk about the sync rates available on the ADSL 
circuit while ignoring the congestion in the backhaul.

My ISP (PlusNet) isn't too bad - they do their own prioritisation and 
shaping to manage bandwidth (in particular, throttling P2P traffic at 
peak times to maintain a decent service) AND they are open about what 
they do and why. But many ISPs appear to have inadequate backhaul 
capacity and their users frequently complain about poor speeds at 
peak times. In these cases, you either set you local limits below the 
poorest rates and thus get poor rates all the time, or you set it 
higher and still suffer from the effects of congestion at peak times.

-- 
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

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