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