On Wednesday 05 December 2001 11:32, Ralf Ronneburger wrote:
Hello Andreas, Actually there is some reply from the server, the whole conversation between the two of them is this:
10:09:40.228711 217.82.186.42.2764 > 213.83.12.10.http: S 120893175:120893175(0) win 5808
(DF) 10:09:40.271757 213.83.12.10.http > 217.82.186.42.2764: S 3703832914:3703832914(0) ack 120893176 win 31944 (DF) 10:09:40.271973 217.82.186.42.2764 > 213.83.12.10.http: . ack 1 win 5808 (DF) 10:09:40.272986 217.82.186.42.2764 > 213.83.12.10.http: P 1:533(532) ack 1 win 5808 (DF) 10:09:40.343660 213.83.12.10.http > 217.82.186.42.2764: . ack 533 win 31944 (DF) The packets go out with an mss of 1452, that is your pmtu should be 1492 (mss+20+20) Is your mtu (and mru) set to 1492 ? (I would suppose it is set to a smaller value)
Now does it still make sense to try, what you've told me to do? First I would check if your mtu (mru) are set to 1492. Your mss seems to be set as if this was your mtu.
And what is the desease I'm curing with that? As far as I understand it: Your running pppoe. That means your ip packets (ppp0) are wrapped in pppoe packets, which are sent through your eth interface. This adds 8 bytes. Your eth Interface has an mtu of 1500, so your pppd should have an mtu of 1492. The server has to be told to send only packets with max 1492 bytes so they can be wrapped in pppoe (by the isp router). This is done with the "-j TCPMSS --clamp-mss-to-pmtu" rule. It discovers your pmtu and sets mss accordingly. If the server sends larger packets, they don't reach your eth Interface. The server is told by the mss value how big the max packet size should be. Now this seems to work. But if your mtu of your ppp0 Interface is smaller than 1492, <speculation> your isp router knows about this from the ppp negotiation and doesn't send you those packets. Now it could tell the server that it should fragment the packet, which doesn't work in some cases etc. </speculation>
But I could be totally wrong and would appreciate any correction. Andreas Baetz ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been scanned for the presence of computer viruses. **********************************************************************