Mailing List Archive: TCP options problem with ipvs-0.2.[56] ???

TCP options problem with ipvs-0.2.[56] ???

Mar 22, 2001, 3:33 AM

Post #1 of 3 (358 views)

Hi,

We had some problems that showed up to be caused by TCP options. Briefly:

Director:
ipvs: 0.2.5, 0.2.6 (tested with both)
kernel: 2.4.2

Real servers:
Kernels: 2.4.0-0.99.23smp, 2.2.16

Symptom:
TCP connections are not esatblished. The 3rd packet from the 3-way handshake
is rejected by Linux-based clients. Exactly the same configuration has been
used for tests, on a different network, and it didn't show up these symptoms.

The symptom diappears if all the following sysctl options are set to 0:
net.ipv4.tcp_timestamps, net.ipv4.tcp_sack, net.ipv4.tcp_window_scaling

Has anyone had similar symptoms ? Is there any reasonable explanation for
this ?

Radu-Adrian Feurdean
mailto: raf@chez.com
-------------------------------------------------------------------
"If the night is silent enough you can hear a Windows NT rebooting"

Re: TCP options problem with ipvs-0.2.[56] ??? [ In reply to ]

wensong at gnuchina

Mar 22, 2001, 7:06 AM

Post #2 of 3 (351 views)

Permalink

On Thu, 22 Mar 2001, Radu-Adrian Feurdean wrote:

>
> Hi,
>
> We had some problems that showed up to be caused by TCP options. Briefly:
>
> Director:
> ipvs: 0.2.5, 0.2.6 (tested with both)
> kernel: 2.4.2
>
> Real servers:
> Kernels: 2.4.0-0.99.23smp, 2.2.16
>
> Symptom:
> TCP connections are not esatblished. The 3rd packet from the 3-way handshake
> is rejected by Linux-based clients. Exactly the same configuration has been
> used for tests, on a different network, and it didn't show up these symptoms.
>
> The symptom diappears if all the following sysctl options are set to 0:
> net.ipv4.tcp_timestamps, net.ipv4.tcp_sack, net.ipv4.tcp_window_scaling
>
>
> Has anyone had similar symptoms ? Is there any reasonable explanation for
> this ?
>

I don't have any clue on it. The 3rd packet should be from the client to
the server? which side do you set those sysctl options? Would you give
tcpdump results on client, load balancer and server?

Regards,

Wensong

Re: TCP options problem with ipvs-0.2.[56] ??? [ In reply to ]

raf at chez

Mar 22, 2001, 11:04 AM

Post #3 of 3 (349 views)

Permalink

On Thu, 22 Mar 2001, Wensong Zhang wrote:
>
> I don't have any clue on it. The 3rd packet should be from the client to
> the server? which side do you set those sysctl options? Would you give
> tcpdump results on client, load balancer and server?

Yes, it is the packet from the client to the server. For some unknown reason,
Linux clients don't send it (if those options are ON). However, it works for
windogs clients. Haven't tested with something else (*BSD,....)

Tomorrow I'll send you the requested tcpdumps.

Radu-Adrian Feurdean
mailto: raf@chez.com
-------------------------------------------------------------------
"If the night is silent enough you can hear a Windows NT rebooting"