[CLUG] ISP throttling
Alex Satrapa
grail at goldweb.com.au
Wed Jan 12 09:56:54 GMT 2005
On 11 Jan 2005, at 23:56, freegazer wrote:
> yeah it was a 256k link so, u guess.
Other things that an ISP can do to affect download by Linux boxen is
change their handling of ECN (Explicit Congestion Notification). Some
routers (eg: SOHO, or cheap ISP level) can't or won't handle ECN
properly. So at the ISP side, maybe they just started clearing the ECN
bit after your later complaints.
You may also have been having problems with packet sizes being too
large, which can be solved by the ISP performing maximum segment size
clamping on their router (this doesn't do much for UDP unfortunately) -
they directly munge the TCP negotiation so that both ends will
negotiate a MSS larger than the TCP over L2TP can handle (if your ISP
recommends setting MTU on an interface to 1460 or lower, this is
because they're using L2TP to receive the packets from Telstra's line
terminating units).
Yes, the ISP can do something to "fix" the problem in both instances,
but this doesn't make it their fault that the problem occurred. All
kinds of equipment exist on the Internet - their interactions are often
unpredictable. ISPs like to say things like, "we don't support Linux"
not because they don't *like* Linux, not because they're trying to
*attack* Linux, but simply because they don't understand it enough to
help you solve problems over the phone.
Supporting Microsoft Windows is fairly easy - the ways that Microsoft
Windows breaks are relatively well documented, to the point that an
experienced technical support person can write a script which will
guide the inexperienced ("level 1") helpdesk person through solving the
problem. Since it's not so easy to diagnose problems with Linux
(Roaring Penguin isn't the only PPPoE client for Linux, and networking
configuration changes significantly between 2.0, 2.4 and 2.6) and then
you've got iptables thrown into the mix.
Please don't go slinging mud at your ISP because you chose to use a
product that they don't know how to support, and as a result something
broke that they couldn't help you fix.
Regards
Alex Satrapa
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