Regarding skb and net_device.

[Pranay Srivastava]

On Saturday, May 3, 2014, Rami Rosen <roszenrami at gmail.com> wrote:
> Hi, Pranay,
>
> First, let's assume that you are talking about IPv4, though you did not
> mention it explicitly. (The principles in IPv6 are quite similar, though)
>
> A packet is sent out in the usual case with the ip_queue_xmit() method.
> The  ip_queue_xmit() method calls the ip_route_output_ports() method
> in order to perform a lookup in the IPv4 routing tables.
>
> see: http://lxr.free-electrons.com/source/net/ipv4/ip_output.c#L352
>
> The results of this IPv4 routing lookup determines on which network device
> (net_device) the packet will be sent. You should look at the code of
> ip_route_output_ports() method in net/ipv4/route.c in order to
> understand the IPv4 routing subsystem and the IPv4 routing lookup.
>
> Packets can, under certain circumstances, be sent by the ip_send_skb()
> method, but this happens when the flow (which consists also of the
> net_device to be used) is known before.
>
> Best Regards,
> Rami Rosen
> http://ramirose.wix.com/ramirosen
>
>
> On Sat, May 3, 2014 at 11:33 AM, Pranay Srivastava <pranjas at gmail.com>
wrote:
>> Hi,
>>
>> This is probably a stupid question, but i'm not able to find the
>> answer. How does the networking subsystem decides which device to use
>> for sending the skb. Can some one please guide me to the particular
>> code. I seem to get lost in there :(
>>
>> --
>>         ---P.K.S
>>
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>
Thanks a lot Professor. It will take some time to digest all of it.  The
book and slides are great resource. Could you also answer my queries on
net_device structure as well?
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