About Connection between PPP and linux Sockets

About Connection between PPP and linux Sockets

[Steven]

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Hi

I have a little question just as the title said?
In Ofono how to connect PPP to Linux socket, when we receive packet from 
network, how the packet go through the kernel to application？

modem -->PPP-->? --> linux kernel(network part)--> socket --> application?

steven
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Re: About Connection between PPP and linux Sockets

[Marcel Holtmann]

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Hi Steven,

> I have a little question just as the title said?
> In Ofono how to connect PPP to Linux socket, when we receive packet from 
> network, how the packet go through the kernel to application？
> 
> modem -->PPP-->? --> linux kernel(network part)--> socket --> application?

it is more like this:

modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket -> application.

With the TTY being in kernel, the PPP being in userspace, and TUN/TAP
etc. begin in the kernel again.

A future enhancement is to use the kernel PPP layer, but we haven't
gotten there yet.

Regards

Marcel

RE: About Connection between PPP and linux Sockets

[Zhang, Zhenhua]

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Hi Marcel,

Marcel Holtmann wrote:
> Hi Steven,
> 
>> I have a little question just as the title said?
>> In Ofono how to connect PPP to Linux socket, when we receive packet
>> from network, how the packet go through the kernel to application？
>> 
>> modem -->PPP-->? --> linux kernel(network part)--> socket -->
>> application? 
> 
> it is more like this:
> 
> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket ->
> application. 
> 
> With the TTY being in kernel, the PPP being in userspace, and TUN/TAP
> etc. begin in the kernel again.
> 
> A future enhancement is to use the kernel PPP layer, but we haven't
> gotten there yet.

I am interested to know how could we use kernel PPP layer instead of gatppp. Shall we add this item into our TODO?
 
> Regards
> 
> Marcel
> 
> 
> _______________________________________________
> ofono mailing list
> ofono(a)ofono.org
> http://lists.ofono.org/listinfo/ofono

Regards,
Zhenhua

RE: About Connection between PPP and linux Sockets

[Marcel Holtmann]

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Hi Zhenhua,

> >> I have a little question just as the title said?
> >> In Ofono how to connect PPP to Linux socket, when we receive packet
> >> from network, how the packet go through the kernel to application？
> >> 
> >> modem -->PPP-->? --> linux kernel(network part)--> socket -->
> >> application? 
> > 
> > it is more like this:
> > 
> > modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket ->
> > application. 
> > 
> > With the TTY being in kernel, the PPP being in userspace, and TUN/TAP
> > etc. begin in the kernel again.
> > 
> > A future enhancement is to use the kernel PPP layer, but we haven't
> > gotten there yet.
> 
> I am interested to know how could we use kernel PPP layer instead of gatppp. Shall we add this item into our TODO?

the kernel PPP line discipline can be used and then LCP and IPCP will be
spoken via a side channel to the kernel. And all the packet handling is
done by the kernel itself via the TTY line discipline. It is a bit more
work than just using a TUN/TAP device. And of course it only works in
real TTYs. Not on the GIOChannel that you get from GAtMux.

Regards

Marcel

Re: About Connection between PPP and linux Sockets

[Steven]

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Hi Zhang
Zhang, Zhenhua wrote:
> Hi Marcel,
> 
> Marcel Holtmann wrote:
>> Hi Steven,
>>
>>> I have a little question just as the title said?
>>> In Ofono how to connect PPP to Linux socket, when we receive packet
>>> from network, how the packet go through the kernel to application？
>>>
>>> modem -->PPP-->? --> linux kernel(network part)--> socket -->
>>> application? 
>> it is more like this:
>>
>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket ->
>> application. 
>>
>> With the TTY being in kernel, the PPP being in userspace, and TUN/TAP
>> etc. begin in the kernel again.
>>
>> A future enhancement is to use the kernel PPP layer, but we haven't
>> gotten there yet.
> 
> I am interested to know how could we use kernel PPP layer instead of gatppp. Shall we add this item into our TODO?
>  

Maybe you can reference to RILD in Android, it used kernel PPP.

B.R

Steven

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RE: About Connection between PPP and linux Sockets

[Zhang, Zhenhua]

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Hi Steven,

Steven wrote:
> Hi Zhang
> Zhang, Zhenhua wrote:
>> Hi Marcel,
>> 
>> Marcel Holtmann wrote:
>>> Hi Steven,
>>> 
>>>> I have a little question just as the title said?
>>>> In Ofono how to connect PPP to Linux socket, when we receive packet
>>>> from network, how the packet go through the kernel to application？
>>>> 
>>>> modem -->PPP-->? --> linux kernel(network part)--> socket -->
>>>> application?
>>> it is more like this:
>>> 
>>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket ->
>>> application. 
>>> 
>>> With the TTY being in kernel, the PPP being in userspace, and
>>> TUN/TAP etc. begin in the kernel again.
>>> 
>>> A future enhancement is to use the kernel PPP layer, but we haven't
>>> gotten there yet.
>> 
>> I am interested to know how could we use kernel PPP layer instead of
>> gatppp. Shall we add this item into our TODO? 
>> 
> 
> Maybe you can reference to RILD in Android, it used kernel PPP.

Thanks. Will take a look then.
 
> B.R
> 
> Steven
> 
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Regards,
Zhenhua

Re: About Connection between PPP and linux Sockets

[Steven]

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Hi Zhang,

Zhang, Zhenhua wrote:
> Hi Steven,
> 
> Steven wrote:
>> Hi Zhang
>> Zhang, Zhenhua wrote:
>>> Hi Marcel,
>>>
>>> Marcel Holtmann wrote:
>>>> Hi Steven,
>>>>
>>>>> I have a little question just as the title said?
>>>>> In Ofono how to connect PPP to Linux socket, when we receive packet
>>>>> from network, how the packet go through the kernel to application？
>>>>>
>>>>> modem -->PPP-->? --> linux kernel(network part)--> socket -->
>>>>> application?
>>>> it is more like this:
>>>>
>>>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket ->
>>>> application. 
>>>>
>>>> With the TTY being in kernel, the PPP being in userspace, and
>>>> TUN/TAP etc. begin in the kernel again.
>>>>
>>>> A future enhancement is to use the kernel PPP layer, but we haven't
>>>> gotten there yet.
>>> I am interested to know how could we use kernel PPP layer instead of
>>> gatppp. Shall we add this item into our TODO? 
>>>
>> Maybe you can reference to RILD in Android, it used kernel PPP.
> 
> Thanks. Will take a look then.

This information is a good start point.
http://www.devdiv.net/viewthread-26543

But only for Chinese people:(

B.R

Steven

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is intended only for the use of the intended recipient and may be confidential and/or privileged of 
Neusoft Corporation, its subsidiaries and/or its affiliates. If any reader of this communication is 
not the intended recipient, unauthorized use, forwarding, printing,  storing, disclosure or copying 
is strictly prohibited, and may be unlawful.If you have received this communication in error,please 
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RE: About Connection between PPP and linux Sockets

[Zhang, Zhenhua]

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Hi Steven,

Steven wrote:
> Hi Zhang,
> 
> Zhang, Zhenhua wrote:
>> Hi Steven,
>> 
>> Steven wrote:
>>> Hi Zhang
>>> Zhang, Zhenhua wrote:
>>>> Hi Marcel,
>>>> 
>>>> Marcel Holtmann wrote:
>>>>> Hi Steven,
>>>>> 
>>>>>> I have a little question just as the title said?
>>>>>> In Ofono how to connect PPP to Linux socket, when we receive
>>>>>> packet from network, how the packet go through the kernel to
>>>>>> application？ 
>>>>>> 
>>>>>> modem -->PPP-->? --> linux kernel(network part)--> socket -->
>>>>>> application?
>>>>> it is more like this:
>>>>> 
>>>>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket ->
>>>>> application. 
>>>>> 
>>>>> With the TTY being in kernel, the PPP being in userspace, and
>>>>> TUN/TAP etc. begin in the kernel again.
>>>>> 
>>>>> A future enhancement is to use the kernel PPP layer, but we
>>>>> haven't gotten there yet.
>>>> I am interested to know how could we use kernel PPP layer instead
>>>> of gatppp. Shall we add this item into our TODO?
>>>> 
>>> Maybe you can reference to RILD in Android, it used kernel PPP.
>> 
>> Thanks. Will take a look then.
> 
> This information is a good start point.
> http://www.devdiv.net/viewthread-26543
> 
> But only for Chinese people:(

Thanks. I have read this before. ;-). The original article is from maxleng's blog:

http://blog.csdn.net/maxleng/archive/2010/05/10/5576509.aspx

However, it's just a big picture about phone stack in Android. It said nothing about how Android works with kernel PPP layer.

> B.R
> 
> Steven
> 
> ---------------------------------------------------------------------------------------------------
> Confidentiality Notice: The information contained in this e-mail and
> any accompanying attachment(s) is intended only for the use of the
> intended recipient and may be confidential and/or privileged of
> Neusoft Corporation, its subsidiaries and/or its affiliates. If any
> reader of this communication is not the intended recipient,
> unauthorized use, forwarding, printing,  storing, disclosure or
> copying is strictly prohibited, and may be unlawful.If you have
> received this communication in error,please immediately notify the
> sender by return e-mail, and delete the original message and all
> copies from your system. Thank you.
> ---------------------------------------------------------------------------------------------------
> _______________________________________________   
> ofono mailing list
> ofono(a)ofono.org
> http://lists.ofono.org/listinfo/ofono

Regards,
Zhenhua

RE: About Connection between PPP and linux Sockets

[Marcel Holtmann]

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Hi Zhenhua,

> >>>>>> I have a little question just as the title said?
> >>>>>> In Ofono how to connect PPP to Linux socket, when we receive
> >>>>>> packet from network, how the packet go through the kernel to
> >>>>>> application？ 
> >>>>>> 
> >>>>>> modem -->PPP-->? --> linux kernel(network part)--> socket -->
> >>>>>> application?
> >>>>> it is more like this:
> >>>>> 
> >>>>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket ->
> >>>>> application. 
> >>>>> 
> >>>>> With the TTY being in kernel, the PPP being in userspace, and
> >>>>> TUN/TAP etc. begin in the kernel again.
> >>>>> 
> >>>>> A future enhancement is to use the kernel PPP layer, but we
> >>>>> haven't gotten there yet.
> >>>> I am interested to know how could we use kernel PPP layer instead
> >>>> of gatppp. Shall we add this item into our TODO?
> >>>> 
> >>> Maybe you can reference to RILD in Android, it used kernel PPP.
> >> 
> >> Thanks. Will take a look then.
> > 
> > This information is a good start point.
> > http://www.devdiv.net/viewthread-26543
> > 
> > But only for Chinese people:(
> 
> Thanks. I have read this before. ;-). The original article is from maxleng's blog:
> 
> http://blog.csdn.net/maxleng/archive/2010/05/10/5576509.aspx
> 
> However, it's just a big picture about phone stack in Android. It said nothing about how Android works with kernel PPP layer.

could be that Andoid uses the kernel PPP and also uses pppd for it. We
are not using pppd on purpose since it is the wrong piece for an
embedded phone solution. We are not using the kernel PPP part, because
we haven't gotten around that yet. It also only works when having real
TTY devices. If your multiplexer runs in userspace then you also have
the problem that you don't have a real TTY. And using a PTS, then you
can just run PPP also in userspace.

Regards

Marcel

Re: About Connection between PPP and linux Sockets

[Steven]

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Hi Marcel，

Marcel Holtmann wrote:
> Hi Zhenhua,
> 
>>>>>>>> I have a little question just as the title said?
>>>>>>>> In Ofono how to connect PPP to Linux socket, when we receive
>>>>>>>> packet from network, how the packet go through the kernel to
>>>>>>>> application？ 
>>>>>>>>
>>>>>>>> modem -->PPP-->? --> linux kernel(network part)--> socket -->
>>>>>>>> application?
>>>>>>> it is more like this:
>>>>>>>
>>>>>>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket ->
>>>>>>> application. 
>>>>>>>
>>>>>>> With the TTY being in kernel, the PPP being in userspace, and
>>>>>>> TUN/TAP etc. begin in the kernel again.
>>>>>>>
>>>>>>> A future enhancement is to use the kernel PPP layer, but we
>>>>>>> haven't gotten there yet.
>>>>>> I am interested to know how could we use kernel PPP layer instead
>>>>>> of gatppp. Shall we add this item into our TODO?
>>>>>>
>>>>> Maybe you can reference to RILD in Android, it used kernel PPP.
>>>> Thanks. Will take a look then.
>>> This information is a good start point.
>>> http://www.devdiv.net/viewthread-26543
>>>
>>> But only for Chinese people:(
>> Thanks. I have read this before. ;-). The original article is from maxleng's blog:
>>
>> http://blog.csdn.net/maxleng/archive/2010/05/10/5576509.aspx
>>
>> However, it's just a big picture about phone stack in Android. It said nothing about how Android works with kernel PPP layer.
> 
> could be that Andoid uses the kernel PPP and also uses pppd for it. We
> are not using pppd on purpose since it is the wrong piece for an
> embedded phone solution. We are not using the kernel PPP part, because
> we haven't gotten around that yet. It also only works when having real
> TTY devices.
I don't think using pppd is a wrong piece for embedded phone, if we 
using pppd, we can ease the ppp part of ofono and also support full ppp 
functionalities, such as auth method(plain text, pap, chap, eap and so on)

  If your multiplexer runs in userspace then you also have
> the problem that you don't have a real TTY. And using a PTS, then you
> can just run PPP also in userspace.

A little question, if we runs multiplexer in kernel space, can we using 
kernel ppp part?

Steven

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Neusoft Corporation, its subsidiaries and/or its affiliates. If any reader of this communication is 
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Re: About Connection between PPP and linux Sockets

[Marcel Holtmann]

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Hi Steven,

> >>>>>>>> I have a little question just as the title said?
> >>>>>>>> In Ofono how to connect PPP to Linux socket, when we receive
> >>>>>>>> packet from network, how the packet go through the kernel to
> >>>>>>>> application？ 
> >>>>>>>>
> >>>>>>>> modem -->PPP-->? --> linux kernel(network part)--> socket -->
> >>>>>>>> application?
> >>>>>>> it is more like this:
> >>>>>>>
> >>>>>>> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket ->
> >>>>>>> application. 
> >>>>>>>
> >>>>>>> With the TTY being in kernel, the PPP being in userspace, and
> >>>>>>> TUN/TAP etc. begin in the kernel again.
> >>>>>>>
> >>>>>>> A future enhancement is to use the kernel PPP layer, but we
> >>>>>>> haven't gotten there yet.
> >>>>>> I am interested to know how could we use kernel PPP layer instead
> >>>>>> of gatppp. Shall we add this item into our TODO?
> >>>>>>
> >>>>> Maybe you can reference to RILD in Android, it used kernel PPP.
> >>>> Thanks. Will take a look then.
> >>> This information is a good start point.
> >>> http://www.devdiv.net/viewthread-26543
> >>>
> >>> But only for Chinese people:(
> >> Thanks. I have read this before. ;-). The original article is from maxleng's blog:
> >>
> >> http://blog.csdn.net/maxleng/archive/2010/05/10/5576509.aspx
> >>
> >> However, it's just a big picture about phone stack in Android. It said nothing about how Android works with kernel PPP layer.
> > 
> > could be that Andoid uses the kernel PPP and also uses pppd for it. We
> > are not using pppd on purpose since it is the wrong piece for an
> > embedded phone solution. We are not using the kernel PPP part, because
> > we haven't gotten around that yet. It also only works when having real
> > TTY devices.
> I don't think using pppd is a wrong piece for embedded phone, if we 
> using pppd, we can ease the ppp part of ofono and also support full ppp 
> functionalities, such as auth method(plain text, pap, chap, eap and so on)

for a mobile telephony stack, pppd is wrong. Once you understand how 3G
missuses PPP for IP and PDP context setup, you see what I mean ;)

>   If your multiplexer runs in userspace then you also have
> > the problem that you don't have a real TTY. And using a PTS, then you
> > can just run PPP also in userspace.
> 
> A little question, if we runs multiplexer in kernel space, can we using 
> kernel ppp part?

Yes, we could. We have a kernel multiplexer, but not tested or
integrated it with oFono or real hardware.

Regards

Marcel

Re: About Connection between PPP and linux Sockets

[=?unknown-8bit?q?R=C3=A9mi?= Denis-Courmont]

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On Fri, 20 Aug 2010 13:33:35 +0200, Marcel Holtmann <marcel@holtmann.org>
wrote:
> for a mobile telephony stack, pppd is wrong. Once you understand how 3G
> missuses PPP for IP and PDP context setup, you see what I mean ;)

For mobile telephony, PPP as a _protocol_ is wrong - sure. That being
stated, I don't see how pppd as a _software_ is better or worse than any
other PPP implementation.

Considering the high bandwidth involved in high HSPA categories, and soon
LTE networks, going through user space seems like a bad idea. That's why
Phonet GPRS has its own kernel network device driver, even though Phonet
can also interact with a TUN device. As such, the PPP-only modems are
hopeless. Then why bother rewriting a custom PPP implementation that will
be suboptimal in any case?

oFono PPP is just as non-performant as pppd in case the user-space AT MUX
is used. And it seems worse in case the kernel AT MUX or a raw TTY is used
(pppd has kernel path then).


So I must be missing something.

-- 
Rémi Denis-Courmont
http://www.remlab.net
http://fi.linkedin.com/in/remidenis

Re: About Connection between PPP and linux Sockets

[Marcel Holtmann]

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Hi Remi,

> > for a mobile telephony stack, pppd is wrong. Once you understand how 3G
> > missuses PPP for IP and PDP context setup, you see what I mean ;)
> 
> For mobile telephony, PPP as a _protocol_ is wrong - sure. That being
> stated, I don't see how pppd as a _software_ is better or worse than any
> other PPP implementation.
> 
> Considering the high bandwidth involved in high HSPA categories, and soon
> LTE networks, going through user space seems like a bad idea. That's why
> Phonet GPRS has its own kernel network device driver, even though Phonet
> can also interact with a TUN device. As such, the PPP-only modems are
> hopeless. Then why bother rewriting a custom PPP implementation that will
> be suboptimal in any case?
> 
> oFono PPP is just as non-performant as pppd in case the user-space AT MUX
> is used. And it seems worse in case the kernel AT MUX or a raw TTY is used
> (pppd has kernel path then).

this is not about performance. It is about actually being able to
control the PPP link from oFono (or any other telephony stack for that
matter). With pppd you have no control points. It either works or you
are in deep sh*t.

Regards

Marcel

Re: About Connection between PPP and linux Sockets

[Steven]

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Hi Marcel,

>> I have a little question just as the title said?
>> In Ofono how to connect PPP to Linux socket, when we receive packet from 
>> network, how the packet go through the kernel to application？
>>
>> modem -->PPP-->? --> linux kernel(network part)--> socket --> application?
> 
> it is more like this:
> 
> modem -> TTY -> PPP -> TUN/TAP -> Kernel Net-Stack -> socket -> application.
> 
> With the TTY being in kernel, the PPP being in userspace, and TUN/TAP
> etc. begin in the kernel again.
> 
> A future enhancement is to use the kernel PPP layer, but we haven't
> gotten there yet.

I got it, thanks

B.R

Steven
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not the intended recipient, unauthorized use, forwarding, printing,  storing, disclosure or copying 
is strictly prohibited, and may be unlawful.If you have received this communication in error,please 
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