[CentOS] Linux Kernel Physical Interface Limit

Wed Jul 14 15:52:02 UTC 2010
Benjamin Franz <jfranz at freerun.com>

On 07/14/2010 08:17 AM, Whit Blauvelt wrote:
> On Wed, Jul 14, 2010 at 09:51:51AM -0500, Tim Nelson wrote:
>> Even if the limit were lower, such as 10 physical interfaces as mentioned
>> before, I have to imagine that the host system would have issues dealing
>> with the number of interrupts needed to *PROPERLY* service all of those
>> interfaces in addition to the other system hardware.
> There may (or may not) be another problem. As of a couple of years ago, on
> some Linux variants (didn't try RHEL/CentOS), I was having trouble even
> getting 6 NICs (on 3 cards) to work if I had IPv6 turned on. 4 NICs worked
> fine.
> Filed some bug reports, and it was evident from the response that very, very
> few Linux users ever go>  4 eth's on a system. Thus the lack of properly
> debugged IPv6 support for that then. Fortunately I don't (yet) need IPv6.
> When I do, it'll be curious to see if the bug is still there.

I've got six machines with 6 Gb interfaces (two on motherboard, 4 on a 
card) right now (the design called for 3 bonded pairs on separate nets 
for redundancy).  I haven't tried IPV6 on them. I had 'issues' with 
bonding and VMs though.

Benjamin Franz