Subject: Re: [vserver] Re: [Vserver] Re: IP alias limitation
From: Herbert Poetzl <herbert@13thfloor.at>
Date: Sat, 28 Jul 2007 10:39:43 +0200

On Sat, Jul 28, 2007 at 11:48:42AM +0930, Mike O'Connor wrote:
> Has this limitation been overcome as yet and if it has 
> what version of tools and kernel is needed ?

yes and no, there are patches to raise that limit to
64 and even more, but it is not really advised, as
the search/comparison is O(n) (at least in the stable
releases), but there will be more options (and no
fixed limit) in the upcoming devel release ...

HTH,
Herbert

> Thanks
> Mike
> 
> Herbert Poetzl wrote:
> > On Wed, Aug 23, 2006 at 10:22:19PM +0200, Bruno wrote:
> >   
> >> On Wednesday 23 August 2006 22:08, Kathy Kost wrote:
> >>     
> >>> Nope.  Once an alias is created, however which way, the system comes up
> >>> with a "16 alias max" message.  Don't recall the actual message.  The
> >>> vserver would not restart and I had to remove the interfaces and reboot
> >>> the entire server.
> >>>
> >>> Kathy
> >>>
> >>>       
> >>>> Does it help to add ip's with the ip add ... command instead of
> >>>> using ifconfig? Aliases are sooo last millennium.
> >>>>
> >>>>
> >>>> /Benny
> >>>>         
> >
> >   
> >> The kernel patch has a maximum of IP addresses per network context
> >> defined.
> >>     
> >
> >   
> >> Context-association of IP addresses is not optimized, thus many
> >> addresses cause some overhead when checking if incoming packets may be
> >> delivered to a guest. (check if IP is available to a guest)
> >>     
> >
> >   
> >> In addition you have 12 bytes allocated per possible IP address: 12 *
> >> 16 = 192 bytes (even if guest has just 1 IP assigned to it)
> >>     
> >
> >   
> >> For the define limiting the count of IP addresses, see
> >> include/linux/vserver/network.h (line 11):
> >>     
> >
> >   
> >> @define NB_IPV4ROOT 16
> >>     
> >
> >   
> >> Note that you may need to check what header the userspace tools get
> >> compiled against.
> >>     
> >
> > also note that this limitation will go away pretty soon :)
> >
> > best,
> > Herbert
> >
> >   
> >> Bruno
> >> _______________________________________________
> >> Vserver mailing list
> >> Vserver@list.linux-vserver.org
> >> http://list.linux-vserver.org/mailman/listinfo/vserver
> >>     
> > _______________________________________________
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> >   
> 
>