Re: [opensuse] a very weird WiFi/HTTPS combo bug
Boris Epstein wrote:
Just an update: just changed the WiFi packet size to 512 at home, and that fixed the problem there too.
If you have to do that, I'd suspect some other problem is causing this. Reducing the MTU is merely masking that problem. It's like driving a car that vibrates at 60 and you "fix" the problem by only driving at 30. IP is supposed to be able to handle different MTUs and fragmentation is one way it does that. MTU discovery may also be used. If you can do a full 1500 bytes on ethernet, but not on WiFi, then I'd start looking at the WiFi gear. -- Use OpenOffice.org http://www.openoffice.org -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
James Knott said the following on 02/13/2009 07:17 AM:
Boris Epstein wrote:
Just an update: just changed the WiFi packet size to 512 at home, and that fixed the problem there too.
If you have to do that, I'd suspect some other problem is causing this. Reducing the MTU is merely masking that problem. It's like driving a car that vibrates at 60 and you "fix" the problem by only driving at 30. IP is supposed to be able to handle different MTUs and fragmentation is one way it does that. MTU discovery may also be used. If you can do a full 1500 bytes on ethernet, but not on WiFi, then I'd start looking at the WiFi gear.
Since you brought up the matter of fragmentation, it may also be worth checking that the "don't fragment" isn't set somewhere along the line on this transmission. Yes, there is probably no reason why it should be, but there is no harm in checking, and it would be a sufficient explanation for the result. -- No problem exists that drink doesn't make worse. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Anton Aylward wrote:
James Knott said the following on 02/13/2009 07:17 AM:
Boris Epstein wrote:
Just an update: just changed the WiFi packet size to 512 at home, and that fixed the problem there too.
If you have to do that, I'd suspect some other problem is causing this. Reducing the MTU is merely masking that problem. It's like driving a car that vibrates at 60 and you "fix" the problem by only driving at 30. IP is supposed to be able to handle different MTUs and fragmentation is one way it does that. MTU discovery may also be used. If you can do a full 1500 bytes on ethernet, but not on WiFi, then I'd start looking at the WiFi gear.
Since you brought up the matter of fragmentation, it may also be worth checking that the "don't fragment" isn't set somewhere along the line on this transmission.
Yes, there is probably no reason why it should be, but there is no harm in checking, and it would be a sufficient explanation for the result.
I thought the "don't fragment" was a control bit in the IP header and if a router couldn't pass it without fragmenting, it was supposed to return an ICMP message back to the source. -- Use OpenOffice.org http://www.openoffice.org -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
James Knott said the following on 02/13/2009 09:50 PM:
I thought the "don't fragment" was a control bit in the IP header and if a router couldn't pass it without fragmenting, it was supposed to return an ICMP message back to the source.
That is quite correct, it is supposed to. However many machines these days are configured to ignore all ICMP messages regardless. This, apparently, started with the good reasons why _some_ ICMP messages should be ignored but sadly a lot of people were not savvy enough to realise that there are ICMP messages that serve an _essential_ purpose. You can still find "advice" on the web to turn *ALL* ICMP off! *sigh* Check all the config along the route, or better still, use wireshark on each segment to see what is *really* going on. -- The older you get, the better you realize you were. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Anton Aylward wrote:
James Knott said the following on 02/13/2009 09:50 PM:
I thought the "don't fragment" was a control bit in the IP header and if a router couldn't pass it without fragmenting, it was supposed to return an ICMP message back to the source.
That is quite correct, it is supposed to.
However many machines these days are configured to ignore all ICMP messages regardless.
This, apparently, started with the good reasons why _some_ ICMP messages should be ignored but sadly a lot of people were not savvy enough to realise that there are ICMP messages that serve an _essential_ purpose.
You can still find "advice" on the web to turn *ALL* ICMP off! *sigh*
Check all the config along the route, or better still, use wireshark on each segment to see what is *really* going on.
Regardless, if the OP is having problems with WiFi and not ethernet, then I'd suspect a WiFi problem. -- Use OpenOffice.org http://www.openoffice.org -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
participants (2)
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Anton Aylward
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James Knott