Default route doesn't change to wireless device (ath0)

Chuck Swiger cswiger at
Thu Sep 8 17:41:00 PDT 2005

Jon Dama wrote:
> On Thu, 8 Sep 2005, John-Mark Gurney wrote:
>>Jon Dama wrote this message on Thu, Sep 08, 2005 at 15:13 -0700:
[ ... ]
>>> True enough.  I think the general idea is that you need a two layer
>>> routing table.  One that keeps tract of what is possible, and one that
>>> keeps track of what is happening w.r.t existing flows.  Once an interface
>>> link goes down, the route in the second table invaliadates and you go back
>>> to the first to find a new route.
>> Isn't this what a routing daemon does, like routed?

Yes, routed keeps track of link state changes, and will adjust the kernel 
routing table appropriately to direct traffic around a downed link (if 
possible, that is).

> No, a routing daemon such as routed discovers the information to put in
> those tables.

Routed does this too, as well as being willing to advertise the routes it knows 
about.  Setting interface metrics appropriately and running routed ought to be 
enough to give a system that will prefer to use your ethernet NIC rather than a 
wireless NIC, if both are available, for example.

On the other hand, Jon is partially right that if you've only got one interface 
that is up, your machine does not need to make any decision about which 
interface to use.  :-)

> In this case, the user + dhcp are fulfilling this task.  I
> doubt that my wireless access point would participate in network RIP or
> router discovery anyways.
> We're only talking about relatively basic functionality here...

True.  The case you're talking about is too simple for routed to help much.

Most access points and "home routers" support RIP and will advertise dynamic 
routes if you tell the device to do so, but this is often disabled by default, 
since advertizing a single default route via DHCP works just as well for the 
common case.


More information about the freebsd-current mailing list