Tftp problems with ARC firmware

Tftp problems with ARC firmware

[Ralf Baechle]

I'd like to point those who you need to use these crude workarounds:

  echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc
  echo 4096 32767 > /proc/sys/net/ipv4/ip_local_port_range

at a new version of tftp-hpa which solves the PMTU problem by disabling it
only for the tftp client and introduces a new -R begin:end option which
allows to limit the port number range.  The changes are about to become
available in the tftp-hpa git repository at
http://www.kernel.org/pub/scm/network/tftp/tftp-hpa.git; see also
http://www.linux-mips.org/wiki/ARC#tftp-hpa.  Please send test reports to
syslinux@zytor.com and linux-mips@linux-mips.org.

  Ralf

Re: Tftp problems with ARC firmware

[Florian Lohoff]

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On Thu, Oct 13, 2005 at 08:32:25PM +0100, Ralf Baechle wrote:
> I'd like to point those who you need to use these crude workarounds:
> 
>   echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc
>   echo 4096 32767 > /proc/sys/net/ipv4/ip_local_port_range
> 
> at a new version of tftp-hpa which solves the PMTU problem by disabling it
> only for the tftp client and introduces a new -R begin:end option which
> allows to limit the port number range.  The changes are about to become
> available in the tftp-hpa git repository at
> http://www.kernel.org/pub/scm/network/tftp/tftp-hpa.git; see also
> http://www.linux-mips.org/wiki/ARC#tftp-hpa.  Please send test reports to
> syslinux@zytor.com and linux-mips@linux-mips.org.

I made a patch against tftpd-hpa for disabling path MTU discovery - Its
in the Debian BTS: 

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=316616

It should already be merged upstream. User "-F" to disable PMTUd.

Flo
-- 
Florian Lohoff                  flo@rfc822.org             +49-171-2280134
                        Heisenberg may have been here.

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Re: Tftp problems with ARC firmware

[Ralf Baechle]

On Fri, Oct 14, 2005 at 12:09:36AM +0200, Florian Lohoff wrote:

> >   echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc
> >   echo 4096 32767 > /proc/sys/net/ipv4/ip_local_port_range
> > 
> > at a new version of tftp-hpa which solves the PMTU problem by disabling it
> > only for the tftp client and introduces a new -R begin:end option which
> > allows to limit the port number range.  The changes are about to become
> > available in the tftp-hpa git repository at
> > http://www.kernel.org/pub/scm/network/tftp/tftp-hpa.git; see also
> > http://www.linux-mips.org/wiki/ARC#tftp-hpa.  Please send test reports to
> > syslinux@zytor.com and linux-mips@linux-mips.org.
> 
> I made a patch against tftpd-hpa for disabling path MTU discovery - Its
> in the Debian BTS: 
> 
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=316616
> 
> It should already be merged upstream. User "-F" to disable PMTUd.

Never made it to HPA - HPA wrote the patches for these two bugs himself
yesterday when I mentioned the problem to him.  His patches are different
in the he disables PMTU discovery entirely - it's not useful for TFTP.
And your patch doesn't work around the other firmware bug which requires
restricting the port range.  We had to get rid of the currently recommended
workaround - it seriously restricts the IP stack; cripples is probably
the right expression for busy servers.

Patch rotting in the Debian bugtracking system seems to become a classic ;-)

  Ralf

Re: Tftp problems with ARC firmware

[Stephen P. Becker]

Ralf Baechle wrote:
> I'd like to point those who you need to use these crude workarounds:
> 
>   echo 1 > /proc/sys/net/ipv4/ip_no_pmtu_disc
>   echo 4096 32767 > /proc/sys/net/ipv4/ip_local_port_range
> 
> at a new version of tftp-hpa which solves the PMTU problem by disabling it
> only for the tftp client and introduces a new -R begin:end option which
> allows to limit the port number range.  The changes are about to become
> available in the tftp-hpa git repository at
> http://www.kernel.org/pub/scm/network/tftp/tftp-hpa.git; see also
> http://www.linux-mips.org/wiki/ARC#tftp-hpa.  Please send test reports to
> syslinux@zytor.com and linux-mips@linux-mips.org.
> 
>   Ralf
> 
> 

I just (finally) got around to testing this (version 0.42), and I still 
need to set ip_no_pmtu_disc to 1 to netboot.  Is this working for anybody?

-Steve