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RE: SVN access became slow

From: Johannes van der Vegt <Johannes.van.der.Vegt_at_applicos.com>
Date: Wed, 6 Jun 2018 10:08:58 +0200

I do "Telnet \\server 3690", and I get:
Connecting To \\server...Could not open connection to the host, on port
3690: Connect failed
I haven't used Telnet before, so maybe I'm doing something wrong?

Running TCPView tool(from SysInternals) shows svnserve.exe with protocol
'TCP' on port 3690, while other ports (other services) do show 'TCPV6'.

I installed SVN 1.10.0 client on the other client PC, and this also gets
slow. Reverting to 1.9.7 solves this again (because it goes straight to
IPv4).
I'm puzzled... Why is 1.10.0 showing this behavior?
Also: Why does SVNServe not provide an IPv6 service on our server PC?

I think for now I will revert back to 1.9.7 on my main PC as well, until I
have a better view of what's going on.

-----Original Message-----
From: Stefan Sperling [mailto:stsp_at_elego.de]
Sent: Tuesday 5 June 2018 15:34
To: Johannes van der Vegt <Johannes.van.der.Vegt_at_applicos.com>
Cc: users_at_subversion.apache.org
Subject: Re: SVN access became slow

On Tue, Jun 05, 2018 at 02:54:01PM +0200, Johannes van der Vegt wrote:
> Right... I installed a second service with the '-6' option. This did
> not make any difference.

Why does this not work? This should work. Can you connect to the SVN service
with telnet to the server's advertised IPv6 address on port 3690? Maybe
svnserve is not listening on the correct
IOPv6 address (see the --listen-host option)?

> Doing more wireshark sniffing:
> - At first, SVN client tries connecting from the local-link IPv6 address.
> There is no response. Two TCP retransmissions fail as well.
> - Second, SVN client tries connecting from the temporary IPv6 address.
> There is no response. Two TCP retransmissions fail as well.
> - Finally, SVN client falls back to IPv4. This is successful.
>
> The other client PC (Win10 Home 1803) runs an older SVN client
> (v1.9.7), and does not try IPv6 first; this one goes straight to IPv4.
> Running the 'svn info' command from that older version on my own PC
> also goes straight to IPv4.
>
> I believe there is no option to force the client to use IPv4?? (except
> specifically entering the IPv4 IP address) Have I found a bug?

I don't think there is a bug here. SVN will simply try addresses returned by
your client system's DNS resolver in turn. Maybe you could configure your
client system's DNS resolver to prefer IPv4 but that would not be a nice
solution.

If your SVN server has an IPv6 address but does not provide service on that
address, this is expected behaviour. There is no way for the SVN client to
know that it should not be trying this address.

If you do not intend to provide SVN service over IPv6, you could also
disable IPv6 entirely on the SVN server machine.
Received on 2018-06-06 10:09:27 CEST

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