Networking Question

[Thomas Scott]

@Michael - to remedy this, I've seen customers deploy things like super
flat topologies with VPLSs to tie it all together. It's always fun to have
to increase someones's mac table size as their apple TVs were edging out
their DHCP servers. I know you're paying me to do this, but an obligatory
"Your network is bad, and you should feel bad" is always on the tip of my
tongue.
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Thomas Scott
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On Mon, Dec 9, 2019 at 10:14 PM Matt Graham <mhgraham at crow202.org> wrote:

> On 2019-12-09 19:39, Michael Butash wrote:
> > Linux networkmanager will assign a higher metric on non-ethernet
> > interfaces (ideally) to de-preference wireless over wired, but they
> > still both get an address.  In the same subnet, the metric is what
> > determines preference.  You can tweak metrics, but usually depend on
> > the network interface and system preferences.
>
> This makes sense.  The machine where I had 2 NICs on the same subnet, 1
> wired, 1 wireless, had the wired NIC with metric 203 and the wireless
> one with metric 304 in the output from "route -n".  Network Manager was
> not involved; just dhcpcd.  OTOH, dhcpcd probably understands what
> "wired" and "wireless" are and sets up the routes and metrics
> accordingly.  I think that if I set the metrics for enp1s0 and wlp3s0 to
> the same number, I'd get the terrible network problems I described
> earlier.
>
> > This has been a problem for decades, but generally managed by
> > networking stack setting metric preference on routes.  Wired == best,
> > wireless, vpn, others, less. [...] This is standard networking.
>
> This is actually the first time I've heard of the "metric" thing in the
> kernel routing table.  This is probably because almost all of the
> machines I've dealt with over the last 20 years have had pretty simple
> networking configurations.
>
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