Providers differ across countries.
European competition laws are interpreted quite differently in different
countries. AFAIK, Deutsche Telekom and France Telecom are monopolies.
ISPs there therefore use the same infrastructure. BT is not. Here there
are differences between ISPs.
http://www.samknows.com/broadband/exchange/MRPOY
Shows service availability in the area where I am, immediately to the
south of the Manchester conurbation.
Recommendations are also affected by service cost. In this country, BT
increases its prices once or even twice a year by just below the ten per
cent threshold where the regulator takes an interest. Sky and TalkTalk
then follow. Individuals then have to make decisions based not just on
shaping policy, the type of CPE supplied, and TV channels specific to
the provider, but on cost.
Negotiation on cost involves a yearly conversation with the provider,
and cashback offers available elsewhere. Recommendations are therefore
problematic.
On 29/12/13 08:54, Dave Taht wrote:
I would like it if we had a couple per-provider recomendations and
relevant discussion.
On Sat, Dec 28, 2013 at 11:36 PM, Sebastian Moeller <[email protected]> wrote:
Rich Brown <[email protected]> wrote:
QUESTION #2: How does CeroWrt use info gleaned from the link layer
adaptation?
The link layer adaptations work in correcting the kernels estimate of a
packets behavior on the wire. In the tc_stab case the kernel calculates the
effective size of the packet on the wire, that is it pretends the packet is
larger than it really is, so for a given bandwidth it estimates the correct
time it takes for that packet to be actually transmitted. In the htb_private
case the kernel keeps the packet's size (more or less) intact but adjusts its
estimate of the packets transmit rate. Both methods boil down to the same idea,
make sure the packet scheduler will only send packet N+1 after packet N has
just cleared the wire.
Specifically, the link layer adaptation all seem to be designed to
compute the actual time it takes to transmit a packet, accounting for
Ethernet & PPPoE header bytes, other overhead, and ATM 48-in-53
framing.
And the annoying size dependent padding of the last ATM cell.
How does CeroWrt use this time calculation? Does it simply make sure
that the target time doesn’t get too low for a particular flow’s queue?
Thanks to the link layer adjustments (lla) cero now estimates the correct
time each packet takes and will not send any faster than the shaped rate allows.
If no lla is performed cero would overestimate the link capacity, send more than
expected and potentially fill the modems bloated buffers. Traditionally people
tried to reduce their shaped rate by >10% to at least account for the 48 in 53
framing, but failed miserably for small packets since overhead and padding can
more than double the wire size of a packet. Note that ACQ packets typically are
small as are voice over IP packets.
I hope this helps
Sebastian
(I could imagine that a short packet over ATM would take 2x the (naive)
expected/calculated time for a packet of that length, and that flow
would be penalized. Is there more to it?)
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Hi Rich
--
Sent from my Android phone with K-9 Mail. Please excuse my brevity.
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