DHCP over InfiniBand Update

DHCP over InfiniBand Update

[Hal Rosenstock]

Hi,

There appear to be two basic approaches to supporting DHCP (over
InfiniBand) in Linux. There's LPF support (4.1.1 based) and older
(3.0.4 based) socket support.

The 4.1.1 LPF patches are:
http://lists.openfabrics.org/pipermail/ewg/2010-May/015265.html
http://lists.openfabrics.org/pipermail/ewg/2010-May/015266.html
http://lists.openfabrics.org/pipermail/ewg/2010-May/015264.html
The last being Matthieu Hautreux's <matthieu.hautreux at cea.fr>
improved XID generation (same as
https://lists.isc.org/mailman/htdig/dhcp-hackers/2009-January/001773.html).

AFAIT an LPF based approach will only work on older kernels (due to
elimination of CONFIG_FILTER support). Is this accurate ?

OFED has two patches for 3.0.4 for a socket approach in
http://www.openfabrics.org/git/?p=~tziporet/docs.git;a=tree;f=dhcp;h=aec68a2905559c8ed91f1157fa11d78cccb266cd;hb=ofed_1_5
dhcp-3.0.4.patch
0001-Make-DHCP-server-print-HW-info.patch

I've been upporting those to a 4.x based DHCP and have a fundamental
question which occurs even with the 3.0.4 socket based version. On the
client machine, the DHCPOFFER in response to the DHCPDISCOVER is
received (seen with tcpdump) but never seems to make it to the
dhclient application. I can't see any kernel stack error counters
incremented so I'm mystified as to what could be going wrong. I've
also tried this on a number of different kernels. Any idea on why this
might be or how to figure out where that packet is going ? I do see
the dhcp client port with netstat -a --udp -n
udp        0      0 0.0.0.0:68                  0.0.0.0:*
udp        0      0 0.0.0.0:68                  0.0.0.0:*
Any idea on what I'm missing ?

Also, is any of this work making it's way into a released DHCP ?
What's the process for this ? Is there some branch in a source
repository where this work is available ?

Thanks in advance for any pointers on all this.

-- Hal
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Re: [ewg] DHCP over InfiniBand Update

[sebastien dugue]

  Hi Hal,

On Tue, 31 Aug 2010 16:09:19 -0400
Hal Rosenstock <hal.rosenstock-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> Hi,
> 
> There appear to be two basic approaches to supporting DHCP (over
> InfiniBand) in Linux. There's LPF support (4.1.1 based) and older
> (3.0.4 based) socket support.
> 
> The 4.1.1 LPF patches are:
> http://lists.openfabrics.org/pipermail/ewg/2010-May/015265.html
> http://lists.openfabrics.org/pipermail/ewg/2010-May/015266.html
> http://lists.openfabrics.org/pipermail/ewg/2010-May/015264.html
> The last being Matthieu Hautreux's <matthieu.hautreux at cea.fr>
> improved XID generation (same as
> https://lists.isc.org/mailman/htdig/dhcp-hackers/2009-January/001773.html).
> 
> AFAIT an LPF based approach will only work on older kernels (due to
> elimination of CONFIG_FILTER support). Is this accurate ?

  Where have you seen that the LPF approach does not work on recent kernels?
AFAICR, the CONFIG_FILTER disappeared a long time ago. Unless I'm missing
something, you only need the CONFIG_PACKET option.

  Sébastien.


> 
> OFED has two patches for 3.0.4 for a socket approach in
> http://www.openfabrics.org/git/?p=~tziporet/docs.git;a=tree;f=dhcp;h=aec68a2905559c8ed91f1157fa11d78cccb266cd;hb=ofed_1_5
> dhcp-3.0.4.patch
> 0001-Make-DHCP-server-print-HW-info.patch
> 
> I've been upporting those to a 4.x based DHCP and have a fundamental
> question which occurs even with the 3.0.4 socket based version. On the
> client machine, the DHCPOFFER in response to the DHCPDISCOVER is
> received (seen with tcpdump) but never seems to make it to the
> dhclient application. I can't see any kernel stack error counters
> incremented so I'm mystified as to what could be going wrong. I've
> also tried this on a number of different kernels. Any idea on why this
> might be or how to figure out where that packet is going ? I do see
> the dhcp client port with netstat -a --udp -n
> udp        0      0 0.0.0.0:68                  0.0.0.0:*
> udp        0      0 0.0.0.0:68                  0.0.0.0:*
> Any idea on what I'm missing ?
> 
> Also, is any of this work making it's way into a released DHCP ?
> What's the process for this ? Is there some branch in a source
> repository where this work is available ?
> 
> Thanks in advance for any pointers on all this.
> 
> -- Hal
> _______________________________________________
> ewg mailing list
> ewg-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org
> http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ewg
> 
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Re: [ewg] DHCP over InfiniBand Update

[Hal Rosenstock]

Hi Sébastien,

On Mon, Sep 6, 2010 at 9:03 AM, sebastien dugue
<sebastien.dugue-6ktuUTfB/bM@public.gmane.org> wrote:
>  Hi Hal,
>
> On Tue, 31 Aug 2010 16:09:19 -0400
> Hal Rosenstock <hal.rosenstock-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>> Hi,
>>
>> There appear to be two basic approaches to supporting DHCP (over
>> InfiniBand) in Linux. There's LPF support (4.1.1 based) and older
>> (3.0.4 based) socket support.
>>
>> The 4.1.1 LPF patches are:
>> http://lists.openfabrics.org/pipermail/ewg/2010-May/015265.html
>> http://lists.openfabrics.org/pipermail/ewg/2010-May/015266.html
>> http://lists.openfabrics.org/pipermail/ewg/2010-May/015264.html
>> The last being Matthieu Hautreux's <matthieu.hautreux at cea.fr>
>> improved XID generation (same as
>> https://lists.isc.org/mailman/htdig/dhcp-hackers/2009-January/001773.html).
>>
>> AFAIT an LPF based approach will only work on older kernels (due to
>> elimination of CONFIG_FILTER support). Is this accurate ?
>
>  Where have you seen that the LPF approach does not work on recent kernels?
> AFAICR, the CONFIG_FILTER disappeared a long time ago. Unless I'm missing
> something, you only need the CONFIG_PACKET option.

The question was based on the README and some code in lpf.c but it
sounds those comments relating to CONFIG_FILTER relate to 2.4 and not
to 2.6 based kernels then. All that is needed with a 2.6 kernel is
CONFIG_PACKET so the PF_PACKET socket can be created and used by lpf.
Right ?

Out of curiousity, why did you choose a PF_PACKET rather than a UDP
socket based approach ? The UDP socket approach seems simpler but
maybe has some other pitfalls.

Thanks again.

-- Hal

>  Sébastien.
>
>
>>
>> OFED has two patches for 3.0.4 for a socket approach in
>> http://www.openfabrics.org/git/?p=~tziporet/docs.git;a=tree;f=dhcp;h=aec68a2905559c8ed91f1157fa11d78cccb266cd;hb=ofed_1_5
>> dhcp-3.0.4.patch
>> 0001-Make-DHCP-server-print-HW-info.patch
>>
>> I've been upporting those to a 4.x based DHCP and have a fundamental
>> question which occurs even with the 3.0.4 socket based version. On the
>> client machine, the DHCPOFFER in response to the DHCPDISCOVER is
>> received (seen with tcpdump) but never seems to make it to the
>> dhclient application. I can't see any kernel stack error counters
>> incremented so I'm mystified as to what could be going wrong. I've
>> also tried this on a number of different kernels. Any idea on why this
>> might be or how to figure out where that packet is going ? I do see
>> the dhcp client port with netstat -a --udp -n
>> udp        0      0 0.0.0.0:68                  0.0.0.0:*
>> udp        0      0 0.0.0.0:68                  0.0.0.0:*
>> Any idea on what I'm missing ?
>>
>> Also, is any of this work making it's way into a released DHCP ?
>> What's the process for this ? Is there some branch in a source
>> repository where this work is available ?
>>
>> Thanks in advance for any pointers on all this.
>>
>> -- Hal
>> _______________________________________________
>> ewg mailing list
>> ewg-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org
>> http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ewg
>>
>
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Re: [ewg] DHCP over InfiniBand Update

[sebastien dugue]

On Mon, 6 Sep 2010 09:15:50 -0400
Hal Rosenstock <hal.rosenstock-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> Hi Sébastien,
> 
> On Mon, Sep 6, 2010 at 9:03 AM, sebastien dugue
> <sebastien.dugue-6ktuUTfB/bM@public.gmane.org> wrote:
> >  Hi Hal,
> >
> > On Tue, 31 Aug 2010 16:09:19 -0400
> > Hal Rosenstock <hal.rosenstock-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >
> >> Hi,
> >>
> >> There appear to be two basic approaches to supporting DHCP (over
> >> InfiniBand) in Linux. There's LPF support (4.1.1 based) and older
> >> (3.0.4 based) socket support.
> >>
> >> The 4.1.1 LPF patches are:
> >> http://lists.openfabrics.org/pipermail/ewg/2010-May/015265.html
> >> http://lists.openfabrics.org/pipermail/ewg/2010-May/015266.html
> >> http://lists.openfabrics.org/pipermail/ewg/2010-May/015264.html
> >> The last being Matthieu Hautreux's <matthieu.hautreux at cea.fr>
> >> improved XID generation (same as
> >> https://lists.isc.org/mailman/htdig/dhcp-hackers/2009-January/001773.html).
> >>
> >> AFAIT an LPF based approach will only work on older kernels (due to
> >> elimination of CONFIG_FILTER support). Is this accurate ?
> >
> >  Where have you seen that the LPF approach does not work on recent kernels?
> > AFAICR, the CONFIG_FILTER disappeared a long time ago. Unless I'm missing
> > something, you only need the CONFIG_PACKET option.
> 
> The question was based on the README and some code in lpf.c but it
> sounds those comments relating to CONFIG_FILTER relate to 2.4 and not
> to 2.6 based kernels then. All that is needed with a 2.6 kernel is
> CONFIG_PACKET so the PF_PACKET socket can be created and used by lpf.
> Right ?

  Absolutely right.

> 
> Out of curiousity, why did you choose a PF_PACKET rather than a UDP
> socket based approach ? The UDP socket approach seems simpler but
> maybe has some other pitfalls.

  For unknown reasons which I did not have time to investigate at the
time, I could not make it work using a plain UDP socket which I agree
should be straightforward. So I did it the LPF way.


  Sébastien.
  

> 
> Thanks again.
> 
> -- Hal
> 
> >  Sébastien.
> >
> >
> >>
> >> OFED has two patches for 3.0.4 for a socket approach in
> >> http://www.openfabrics.org/git/?p=~tziporet/docs.git;a=tree;f=dhcp;h=aec68a2905559c8ed91f1157fa11d78cccb266cd;hb=ofed_1_5
> >> dhcp-3.0.4.patch
> >> 0001-Make-DHCP-server-print-HW-info.patch
> >>
> >> I've been upporting those to a 4.x based DHCP and have a fundamental
> >> question which occurs even with the 3.0.4 socket based version. On the
> >> client machine, the DHCPOFFER in response to the DHCPDISCOVER is
> >> received (seen with tcpdump) but never seems to make it to the
> >> dhclient application. I can't see any kernel stack error counters
> >> incremented so I'm mystified as to what could be going wrong. I've
> >> also tried this on a number of different kernels. Any idea on why this
> >> might be or how to figure out where that packet is going ? I do see
> >> the dhcp client port with netstat -a --udp -n
> >> udp        0      0 0.0.0.0:68                  0.0.0.0:*
> >> udp        0      0 0.0.0.0:68                  0.0.0.0:*
> >> Any idea on what I'm missing ?
> >>
> >> Also, is any of this work making it's way into a released DHCP ?
> >> What's the process for this ? Is there some branch in a source
> >> repository where this work is available ?
> >>
> >> Thanks in advance for any pointers on all this.
> >>
> >> -- Hal
> >> _______________________________________________
> >> ewg mailing list
> >> ewg-ZwoEplunGu1OwGhvXhtEPSCwEArCW2h5@public.gmane.org
> >> http://lists.openfabrics.org/cgi-bin/mailman/listinfo/ewg
> >>
> >
> --
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> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
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