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Hello,
On Sun, 18 Aug 2002, Greg Woods wrote:
> I'm having a huge problem with my LVS mail cluster. The real servers
> cannot connect to certain remote sites, even though other machines on the
> same network with them can. I have traced the problem to the fact that,
> after applying the hidden patch to a 2.4.18 kernel, the SYN packets for
> outbound connections are being sent out with "SWE" flags set (as shown
> by tcpdump). This seems to cause some remote machines not to treat it as
> a SYN, and I see no response. Machines running a stock Red Hat 2.4.9-34
> kernel, tcpdump shows only "S" set, and the connection works fine. This
> is obviously some kind of kernel configuration problem, but I've got no
> clue. Has anyone seen anything like this before?
ECN - Explicit Congestion Notification
http://www.icir.org/floyd/ecn.html
The mentioned TCP flags:
W CWR (Congestion Window Reduced)
E ECN Echo Sent
S SYN
> I have had so many problems getting this to work, I am under a whole
> bunch of pressure to get things working. I'm about to go back to DNS
> round robining for load balancing.
I don't know why the hidden flag is related to ECN, may be
you enabled ECN in the kernel config?
CONFIG_INET_ECN: /proc/sys/net/ipv4/tcp_ecn
> --Greg
Regards
--
Julian Anastasov <ja@xxxxxx>
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