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From: | Thomas Richter (TCD - DE/Dresden) |
Subject: | [lwip-users] at ZeroWindowProbe the response is not ZeroWindowProbeAck |
Date: | Tue, 17 May 2011 16:12:12 +0200 |
User-agent: | Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.2.17) Gecko/20110414 Lightning/1.0b2 Thunderbird/3.1.10 |
Hi, during some tests with lwIP 1.4.0 I could provoke that the WindowSize is 0. This tells the sender to stop sending. The next sequence by the sender is a TCP_ZeroWindowProbe sequence (some infos to TCP Analyze Sequence Numbers with Wireshark: http://wiki.wireshark.org/TCP_Analyze_Sequence_Numbers). But lwIP responses not with a sequence TCP_ZeroWindowProbeAck, it sends a new TCP_ZeroWindow sequence. With another device with another TCP/IP stack the following I can observe: time 1: 192.168.1.1 ==> 192.168.1.100 seq.no.: 6150 ack.no.: 2532 next seq.no.: 6151 time 2: 192.168.1.1 <== 192.168.1.100 seq.no.: 2532 (is the expected sequence) ack.no.: 6150 (is the expected ACK) This will be continued until the receiver (192.168.1.100) can handle new data. With lwIP the following I can observe: time 1: 192.168.1.1 ==> 192.168.1.100 seq.no.: 8351 ack.no.: 17202 next seq.no.: 8352 time 2: 192.168.1.1 <== 192.168.1.100 seq.no.: 17202 (is the expected sequence) ack.no.: 8352 (is not the ACK to 8351) The increase of acknowledge number by 1 is curios. Why lwIP reacts different? What can I do that the acknowledge number not increases? Thanks for any help. Best regards Thomas
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