[PLUG] Understanding Networking Components

John Meissen john at meissen.org
Sun Apr 1 23:08:35 UTC 2012


rshepard at appl-ecosys.com said:
>    Doesn't the TC/IP software look at the RUNNING interface? In the case of
> the Sony, the routing table has a default gateway for wlan0. 

No. TCP/IP doesn't know physical interfaces. It knows IP address. How the 
packet gets out onto a physical wire is someone else's problem.

Yes, you have a default gateway for wlan0. But you said you ALSO had one for 
eth0.

>    This raises the question of why it would pick the non-running eth0 when
> there's a default gateway for the wlan0. 

Because the routing table says it's available. And either it finds that route 
first, or it has a lower metric...

> And, shouldn't the OS turn off the eth0 routes when the system boots without 
> an ethernet cable attached? 

Normally I would think so, yes.





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