Hi, All,
I have a problem about libpcap ring buffer. The problem is the packets captured 
by libpcap1.1.1 which uses ring 
buffer are truncated. The detail is as the following.
 
I have two machines. One is A, one is B. A and B are connected directly by 
twisted pair with Giga Ethernet NICs.I 
used tcpreplay to send packets from A to B and capture data with tcpdump for 
both A and B. I found many of packets whth UDP payload truncated for B, the 
receiver, but not for A. This problem is found for tcpdump4.1.1 with 
libpcap1.1.1.
 
I made the same test with tcpdump3.4 with libpcap0.9.4. This problem is not 
seen. The difference between these two tests are two libpcaps are different 
version. One is 0.9.4, which does not use ring buffer, one is 1.1.1, which used 
ring buffer.
 
The two machines are installed Suse Linux 10.2, the kernel is 2.6(I forgot the 
detail version info, if needed, I 
can add later).
 
I also tested to send data to B from C by LAN from another NIC. The libpcap is 
1.1.1. This truncate problem is not seen. So the problem is related with NIC 
direct connection and libpcap ring buffer, I think. Till now I still can not 
figure out what is wrong. Maybe it is my NIC problem? But I found same problem 
when I send packets from B to A and capture packets at B. Is it a bug of 
libpcap 1.1.1? I think it is not. Maybe it is my NIC configuration 
problem? But I checked with ethtool and ifconfig and found nothing to add or 
change. The two GE NIC are working at 1000Mbps full mode. Or it is a SuSe Linux 
bug? Anyone can help? Thanks a lot!
 
Roger   

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