Re: [gentoo-user] Strange network behaviour: NIC goes down, DHCP lease renewal fails (WORKED AROUND)

[Marc Joliet <marcec@gmx.de>]

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Am Fri, 06 Mar 2015 21:35:45 +0200
schrieb Alan McKinnon <alan.mckinnon@gmail.com>:

> On 06/03/2015 20:45, Marc Joliet wrote:
> > First of all, thanks to everybody who responded so far.
> > 
> > I wanted preface my reply to Alan by mentioning that the local sysadmin made
> > changes to the DHCP server that appear to have worked around whatever the issue
> > is.
> > 
> > I don't fully understand the error analysis (something to do with the DHCP
> > client reaching a particular state and sending DHCP packets that something
> > in-between it and the DHCP server doesn't like and that might result in vendor
> > dependent behaviour), but what the DHCP server now does is tell the client to
> > use the broadcast address as the DHCP server address (which is weird, because
> > the DHCP clients always switch to the broadcast address after a timeout, but of
> > course I'm no DHCP expert).  The affected PCs have been working normally all
> > day today.
> 
> In light of what you say below:
> 
> 
> I'd be interested to hear what your sysadmin has to say; dhcp is one of
> those things that JustWork(tm) - it uses regular tcp and nothing funny
> about it at all. The only thing normally between your NIC and the dhcp
> server is a switch, so that's what I'd be looking at.

That's also why I was confused about the whole thing and why I originally
thought that it was either a power management issue or some sort of network
problem.

I'll see if I can ask when I'm there again next week.

[...]
> I wasn't aware you had e1000e hardware - those are about as reliable as
> they come. I've used many of them and never had the slightest trouble at
> all. By all means study up on firmware and driver options - if you don;t
> know much about that area it's very illuminating to find out more. But
> based on experience I'd say the chances of finding an oddity with e1000e
> are slim, and I'd be looking at a misconfigured switch.

That's pretty much what the sysadmin said, too, when I asked what he thought
of the "power management issue" idea.

> There are some strange switches out there that let you make crazy
> configuration, like eg blanket drop all broadcast traffic on one or more
> ports. That's where I'd be looking first.

Yeah, that agrees with my instinct that it's most something to do with the
switch.

-- 
Marc Joliet
--
"People who think they know everything really annoy those of us who know we
don't" - Bjarne Stroustrup

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