[CentOS] CentOS 6 : Network Interface Naming

Fri Nov 15 23:12:21 UTC 2013
SilverTip257 <silvertip257 at gmail.com>

On Fri, Nov 15, 2013 at 2:33 PM, Scott Robbins <scottro at nyc.rr.com> wrote:

> On Fri, Nov 15, 2013 at 01:50:18PM -0500, SilverTip257 wrote:
> > Hello All,
> >
> > I have one CentOS 6 KVM virtualization server that I built around a year
> > ago (best I can tell it was in October 2012) at which time I would have
> > been installing 6.3 [0].  That particular install used the Consistent
> > Network Device Naming [1] conventions (PCIe NICs are p1p1, p1p2).
> This regression is a combo RedHat/Dell idea, IIRC.  That may be why it's
> that way on a Dell machine.  On Fedora, which usually shows what new
> regressions will be in RH, it's gotten harder to fix with each iteration.
> To make it worse, at least on Fedora (and again, many of their ideas,
> whether good or bad for servers, get into RedHat) has apparently now been
> intertwined with systemd.  At first, one simply had to remove the
> biosdevnames rpm to fix it.  Now, one has to do that, and also add, (in
> Fedora, with grub2) net.ifnames=0 to the kernel line.  (Note that this was
> for Fedora 19, not sure if they at least removed biosdevnames in F20).

I'm not tied to wanting my network interfaces to be ethX.
Once my servers are configured, I'm generally not changing anything, so for
all it matters they could be called wan0, etc.

I actually think some of the conventions are worthwhile (ex: em for
embedded, pXpY for PCI cards - I've not seen any others on Fedora/CentOS).
 I believe embedded NIC naming on Dell hw starts with em1 rather than em0
which is odd (we start counting at zero!).

> To make it even more of a mess, (again, this is judging from Fedora, which
> is good to keep on hand to see what new decisions good and bad will be made
> by RH), I think biosdevnames gave it one name and then the whole systemd
> thing gave it another.  So, it would boot up as say p12p but in
> /etc/sysconfig/network-scripts it would show up as ifcfg-p1p2p or something
> like that. (I'm making these names up, but that was the general idea.)

I did see something similar to this, I believe it was on a Fedora system I
was using for testing ... I don't recall which release though.

RHEL7 ought to have some "Easter eggs" for us. ;)

> Some people consider it a good thing, especially when moving drives between
> machines, but aside from it being something new, which isn't necessarily
> improved, it breaks various working scripts.
> Like you, I consider it a regression, but of course, that's only my
> opinion, and many experienced folks disagree, thinking it's a good
> thing--although I'm sure that even they would agree that they better figure
> out if biosdevname or something else will be handling it so that it is at
> least consistent.

I'm not calling the biosdevname conventions a regression.
But what I am calling a regression is all the flip flopping between the old
convention and the new one, especially on two nearly identical hardware
builds and OS builds for that matter.

> Actually, I think (but am not sure, that in VMs, even Fedora will use the
> eth0, eth1 system rather than the new naming scheme.  Not just KVM, but
> also VirtualBox, VMware, and so on--that has been my experience with CentOS
> VMs at least.
> --
> Scott Robbins
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//  SilverTip257  //