Two network interfaces [copy to the list]

Benoit Plessis b.plessis at doyousoft.com
Tue Feb 20 03:32:36 CST 2007


You cannot setup two network interfaces with the same IP address
without expecting major problems.
Among other thing rp_filter, arp table and many other thing will get
in your way before this kind of configuration could work.

If you want interface failover you really need to look at bonding interfaces
and the correct configuration for your distribution (although you can do 
some
test using the document i pointed to you ( 
http://linux-ip.net/html/ether-bonding.html).

Regards

Sjouk Janssen a écrit :
>
> Hi Benoit,
>
> Hereby the networkconfig files
>
>
> [root at nlehvsfh1pe011 network-scripts]# more ifcfg-eth0
> DEVICE=eth0
> BOOTPROTO=static
> BROADCAST=130.139.175.255
> HWADDR=00:18:8b:7c:6d:02
> IPADDR=130.139.161.88
> NETMASK=255.255.240.0
> NETWORK=130.139.160.0
> ONBOOT=yes
> TYPE=Ethernet
> GATEWAY=130.139.160.1
> USERCTL=no
> IPV6INIT=no
> PEERDNS=yes
>
> [root at nlehvsfh1pe011 network-scripts]# more ifcfg-eth1
> DEVICE=eth1
> BOOTPROTO=static
> BROADCAST=130.139.175.255
> HWADDR=00:18:8b:7c:6d:04
> IPADDR=130.139.161.89
> NETMASK=255.255.240.0
> NETWORK=130.139.160.0
> ONBOOT=yes
> TYPE=Ethernet
> GATEWAY=130.139.160.1
> USERCTL=no
> IPV6INIT=no
> PEERDNS=no
> regards
>
>
> Sjouk Janssen
> Senior System Manager, Development Process Support,
> Philips Consumer Electronics,
> Building SFH1.045 - Glaslaan 2 - Eindhoven
> P.O. Box 80002, 5600 JB Eindhoven
> The Netherlands
> Tel: +31 40 27 37323, Fax: +31 40 27 33416
> E-mail: sjouk.janssen at philips.com
>
>
>
>
>
>
>
>
>
> *Benoit Plessis <b.plessis at doyousoft.com>*
>
> Sent by:
> linux-poweredge-bounces at dell.com
>
> 2007-02-19 23:52
>
> 	
> To
> 	linux-poweredge at dell.com
> cc
> 	
> Subject
> 	Re: Two network interfaces [copy to the list]
> Classification
> 	
>
>
>
> 	
>
>
>
>
>
>
> Hi,
> as said before your network configuration would be helpfull in resolving
> this problem, but I can
> see one explanation of this.
>
> Let's say eth0 configuration is like this:
>       address => 192.168.1.1/24
>       gateway => 192.168.1.254
> and eth1 is like this one:
>       address => 192.168.1.2/24
>
> In this case if you unplug eth0 cable, the host would be unable to reach
> it's gateway which
> is configured using eth0 and you won't be unable to ping it _from
> another network._
> To be able to do this you need to specific two gateway, one for each
> interface.
>
> Anyway if you really need HA on the network take a look at the linux
> bonding driver:
> http://linux-ip.net/html/ether-bonding.html
>
> benoit
>
> Sjouk Janssen wrote:
> >
> > Dear,
> >
> > I have two network interfaces in a DELL 2950.
> > Both are configured and are working, but if I take out the network
> > cable of eth0 interface the whole machine is blocked.
> > Means you can not ping to the machine at all not on eth0 and not on 
> eth1.
> > Is this a known issue.
> >
> > Sjouk Janssen
> > Senior System Manager, Development Process Support,
> > Philips Consumer Electronics,
> > Building SFH1.045 - Glaslaan 2 - Eindhoven
> > P.O. Box 80002, 5600 JB Eindhoven
> > The Netherlands
> > Tel: +31 40 27 37323, Fax: +31 40 27 33416
> > E-mail: sjouk.janssen at philips.com
> >
> >
> >
> > The information contained in this message is confidential and may be
> > legally privileged. The message is intended solely for the
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> > notified that any use, dissemination, or reproduction is strictly
> > prohibited and may be unlawful. If you are not the intended recipient,
> > please contact the sender by return e-mail and destroy all copies of
> > the original message.
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> The information contained in this message is confidential and may be 
> legally privileged. The message is intended solely for the 
> addressee(s). If you are not the intended recipient, you are hereby 
> notified that any use, dissemination, or reproduction is strictly 
> prohibited and may be unlawful. If you are not the intended recipient, 
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-- 
Benoit Plessis					+33 4 67 36 42 59
<b.plessis at doyousoft.com>
Ingénieur Réseau
Responsable Infrastructure Système & Réseau.
do|you|soft



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