[CALUG] Nic naming; CALUG Digest, Vol 51, Issue 16

[Walt Smith]

hi,

I scanned by eye an article recently on this issue, and 
remembered it because I had not heard of it before.
Apparently, if a "pc" type box has multiple ethernet interfaces,
it's possible that on each boot the designators can occur
in different sequences. Of course, this causes a naming problem for
sys admins.

a google might find the article; I probably saw it on lwn.net.


Walt........


--- On Wed, 3/23/11, calug-request at unknownlamer.org <calug-request at unknownlamer.org> wrote:

> From: calug-request at unknownlamer.org <calug-request at unknownlamer.org>
> Subject: CALUG Digest, Vol 51, Issue 16
> To: calug at unknownlamer.org
> Date: Wednesday, March 23, 2011, 12:00 PM
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> Today's Topics:
> 
>    1. Random Network Interfaces (Randal T.
> Rioux)
>    2. Re: Random Network Interfaces (Jim
> Bauer)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Tue, 22 Mar 2011 23:32:31 -0400
> From: "Randal T. Rioux" <randy at procyonlabs.com>
> Subject: [CALUG] Random Network Interfaces
> To: calug at unknownlamer.org
> Message-ID: <4D8969CF.2090202 at procyonlabs.com>
> Content-Type: text/plain; charset=ISO-8859-1
> 
> Greetings.
> 
> I haven't used Linux as a router/firewall in 15 years.
> Usually use
> OpenBSD or dedicated appliances. I wanted to give RHEL6 a
> shot and
> experienced some oddities.
> 
> I've also tested this with Slackware 13.1 for the record.
> 
> I have 8 NICs on an IBM x345. With OpenBSD, I can reboot
> and switch
> cables and networks and the NIC devices are always named
> the same.
> 
> Doing the same with RHEL and Slackware keeps
> incrementing/adding/removing eth's each time (messing up IP
> assignments
> and causing general mayhem), i.e. eth0 because eth3, eth5
> is gone, etc.
> 
> Is this a feature? Can somebody explain this to me? My Web
> search foo
> must be weak this evening.
> 
> Thanks, folks.
> 
> Randy
> 
> 
> 
> ------------------------------
> 
> Message: 2
> Date: Wed, 23 Mar 2011 06:58:50 -0400
> From: Jim Bauer <jfbauer at comcast.net>
> Subject: Re: [CALUG] Random Network Interfaces
> To: calug at unknownlamer.org
> Message-ID: <4D89D26A.9070905 at comcast.net>
> Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
> 
> On 03/22/2011 11:32 PM, Randal T. Rioux wrote:
> > Greetings.
> >
> > I haven't used Linux as a router/firewall in 15 years.
> Usually use
> > OpenBSD or dedicated appliances. I wanted to give
> RHEL6 a shot and
> > experienced some oddities.
> >
> > I've also tested this with Slackware 13.1 for the
> record.
> >
> > I have 8 NICs on an IBM x345. With OpenBSD, I can
> reboot and switch
> > cables and networks and the NIC devices are always
> named the same.
> >
> > Doing the same with RHEL and Slackware keeps
> > incrementing/adding/removing eth's each time (messing
> up IP assignments
> > and causing general mayhem), i.e. eth0 because eth3,
> eth5 is gone, etc.
> >
> > Is this a feature? Can somebody explain this to me? My
> Web search foo
> > must be weak this evening.
> >
> 
> This might be the same thing I noticed a while back with
> ubuntu when I 
> replaced some ancient network cards with something more
> modern and the 
> eth numbers all changed (except for the one card I left in
> place).  I 
> tracked it to udev.  It remembers the MAC addresses
> and if eth0 had 
> 01:02:03:04:05:06 then eth0 will always have that mac
> address.  So it 
> you replace that card with another, the new card will get
> the next 
> available ethN.  And if you ever put back that old
> card, it'll reappear 
> as eth0.  I believe
> /etc/udev/rules.d/70-persistent-net.rules is where 
> that is recorded.
> 
> 
> 
> 
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> End of CALUG Digest, Vol 51, Issue 16
> *************************************
>