Re: Multiple interfaces with the same IP address

[I am sorry for not sending cc: to the list]

On Thu, 2007-05-03 at 10:44 -0400, Brian A. Seklecki wrote:
> I've never used the bonding feature in RHEL described here; but I've
> used Cisco IOS EthernetChannel, FreeBSD Netgraph, OpenBSD trunk(4); --
> all 802.3ad + LACP compliant.
> 
> They all use underlying physical interfaces in IPv4-less mode; while
> assigning IPv4 to the new logical a
> ddress.
> 
> You're saying that is not the case with this implementation?
> 
> ~BAS

It looks like your configuration: physical NICs do not have IP, the
virtual bonding does:

$ ifconfig

bond0     Link encap:Ethernet  HWaddr 00:0C:29:76:C2:C2  
          inet addr:192.168.2.104  Bcast:192.168.2.255 
          inet6 addr: fe80::20c:29ff:fe76:c2c2/64 Scope:Link
...
eth1      Link encap:Ethernet  HWaddr 00:0C:29:76:C2:C2  
          inet6 addr: fe80::20c:29ff:fe76:c2c2/64 Scope:Link
...
eth2      Link encap:Ethernet  HWaddr 00:0C:29:76:C2:CC  
          inet6 addr: fe80::20c:29ff:fe76:c2c2/64 Scope:Link
...

And the log is full of 
error on subcontainer 'ia_addr' insert (-1) 
error on subcontainer 'ia_addr' insert (-1) 

Jan

> On Thu, 2007-05-03 at 09:53 +0200, Jan Safranek wrote:
> > On Mon, 2007-04-30 at 14:12 -0400, Brian A. Seklecki wrote:
> > > > Unfortunately it's quite common to have one IP shared among more
> > > > interfaces - e.g. in PPTP server. 
> > > 
> > > This is a proxy-arp config?  Are we talking about an embedded platform
> > > here?
> > 
> > No, it's simple Red Hat Linux box.
> > 
> > > Besides, if this is some type of RAS/Concentrator appliance, wouldn't
> > > there be a separate management interface for system-service abstraction?
> > 
> > Well, I do not know the customer configuration in detail, but I am able
> > to reproduce the ugly log messages by setting channel bonding for
> > cluster: 
> > http://kbase.redhat.com/faq/FAQ_79_258.shtm
> > 
> > 
> > Anyway, I think it's not that important why there is such configuration
> > - the customer just wants it. I went through some of the MIBs and it
> > seems to me that IP-MIB does not allow to manage/monitor two interfaces
> > with the same IP address - there would be two values for one OID (e.g.
> > if both eth0 and eth1 have address 5.5.5.5, then e.g.
> > IP-MIB::ipAddressIfIndex.ipv4."5.5.5.5" should have value 2 and 3, which
> > is not possible from MIB point of view). 
> > 
> > So, if I understand it correctly, the second interface will be invisible
> > in IP-MIB. The appropriate CONTAINER_INSERT will fail, causing memory
> > leak (fixed by patch #1710632) and ugly error message every 30 seconds.
> > 
> > I'll try to get rid of the periodical error messages and display
> > something meaningful only once.
> > 
> > Jan
> > 
> > 
> > 
> > 
> > 
> > 
> > 


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