drivers/net/usb/asix - Re: WS-UL220G USB 2.0 Gigabit Ethernet Adapter in Dell Inspiron 700m laptop

[Smoot Carl-Mitchell]

On Fri, 2009-07-10 at 19:19 -0400, David Curtis wrote:

> >From 'man route', 
> 
> "Metric - The 'distance' to the target (usually counted in hops). It
> is not used by recent kernels but may be needed by routing daemons"
> 
> My use of the word 'hop' was correct, I did not say anything about
> TTL, and I know full well that routing metrics and TTL have nothing to
> do with each other.  But as it says above, metrics are not in use by
> recent kernels, which makes the whole thing moot.
> 

Agreed.

I think the manual is incorrect.  There is a conflation between "hop
count" and "metric".  I believe the original confusion was the "metric"
used by RIP was the "hop count".  More modern routing protocols define
the metric differently and can take into account link speed among other
factors.

TTL was originally defined as the time to live in seconds.  It
supposedly takes into account router and switching delays.  In practice
it has devolved into just the hop-count at the ip routing layer.

> > The metrics in the routing table are only are relative to other local
> > routes.  The value is used to set routing preferences where there is
> > more than a single path to a remote network.
> 
> Which is why I find the network segment the node is on, to have a metric of 29 and not 0, kinda strange.

That is a bit weird.

> 
> Maybe the OP is using some type of routing package that might be
> getting confused by the local network segment being moved from eth0 to
> eth2. But I doubt that on a laptop.

Here is another example of some oddball metrics on my notebook.  I have
no idea why the metrics are set to 2 and 1000 on my wireless interface.
But as you say, it does not make any difference, since the metric is not
used.

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
192.168.130.0   0.0.0.0         255.255.255.0   U     0      0        0
vmnet8
192.168.129.0   0.0.0.0         255.255.255.0   U     0      0        0
vmnet1
192.168.128.0   0.0.0.0         255.255.255.0   U     2      0        0
ath0
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0
ath0
0.0.0.0         192.168.128.1   0.0.0.0         UG    0      0        0
ath0
  
-- 
Smoot Carl-Mitchell
Computer Systems and
Network Consultant
smoot at tic.com
+1 480 922 7313
cell: +1 602 421 9005