Problems to enable 3 Interfaces

guif83 · #1 25th January 2010, 06:17 PM

Hi!

I have 3 Interfaces for a different LAN's and when I start one interface the another interfaces goes down.
How can it's possible?

I configure my ethernets as:

Code:

/sbin/ifconfig eth0 172.16.3.108 netmask 255.255.0.0 broadcast 172.0.255.255
/sbin/ifconfig eth1 172.16.3.109 netmask 255.255.0.0 broadcast 172.0.255.255
/sbin/ifconfig eth2 172.16.3.1110 netmask 255.255.0.0 broadcast 172.0.255.255

madhavdiwan · #2 25th January 2010, 07:09 PM

two things you should check
first:
since ( from our post above) all of these interfaces appear to be on the same LAN network .. what interface is your default for that network?

check your routing .. /sbin/route -n .. chances are your interface s are fine .. but your packets are coming in one interface from the network and leaving the systems via the default interface for that network. ,

try using one interface with ip aliases for the other two ips .. should resolve your routing issue
if you MUST use three interfaces on the same lan ( only reason i can think of is for some odd reason like needing more bandwidth) then you would be better off bonding all three interfaces and making ip aliases on the bond

and second:
your last line makes no sense: you can never have an IP address such as 172.16.3.1110 in
/sbin/ifconfig eth2 172.16.3.1110 netmask 255.255.0.0 broadcast 172.0.255.255

jenaniston · #3 25th January 2010, 07:40 PM

The /etc/sysconfig/network-scripts/ directory should have seperate files . . .
ifcfg-eth0 and ifcfg-eth1 and ifcfg-eth2
(or different names if you name interfaces)
at least if all is configured well - I'm pretty sure from my experience anyway.

and your typo aside . . . all the IP addresses belong to the same 172.16.0.0/16 subnet - with the same broadcast address (as you undoubtedly already know)
and I also don't see how that should make any difference either.

Good luck.

guif83 · #4 26th January 2010, 05:42 PM

In /etc/sysconfig/network-scripts/ I don't have any file as ifcfg-ethx

and when I use the command sys-unconfig in the config i see another time my interfaces!

scott32746 · #5 26th January 2010, 07:06 PM

On eth2 172.16.3.1110 is the correct ?

guif83 · #6 27th January 2010, 09:54 AM

sorry for this Ip. There is an example.

This is my actually configuration:

/sbin/ifconfig eth0 11.0.1.41 netmask 255.255.255.0 broadcast 11.0.1.255
route add default gw 11.0.1.255 eth0

/sbin/ifconfig eth1 10.110.206.59 netmask 255.255.255.0 broadcast 10.110.206.255
route add default gw 10.110.206.12 eth1

/sbin/ifconfig eth2 172.16.3.108 netmask 255.255.0.0 broadcast 172.0.255.255

madhavdiwan · #7 27th January 2010, 12:12 PM

.. this is completely different than your first post.. , i understand if you wanted to keep the ips unknown .. but if they are internal LAN Ips it really does not matter if you tell us what they really are up front.

from your "actual" configuration .. the problem i see is that you are specifying the default route TWICE.. you can only have ONE default route for the entire system.

you will need to define networks beyond your gateways to the system more specifically.

This is beyond my scope at this time : I believe you need to learn routing.
I suggest you sit with a network admin and also pick up a good routing book .. there are a number of books available for linux networking. The route man page is also a good place to start , look at the Examples section: t has some very basic examples of how to use the route command.

man route

scott32746 · #8 27th January 2010, 12:39 PM

Looks like you are not using the correct netmask
# ipcalc -m 11.0.1.41
NETMASK=255.0.0.0
# ipcalc -m 10.110.206.59
NETMASK=255.0.0.0
# ipcalc -m 172.16.3.108
NETMASK=255.255.0.0

guif83 · #9 28th January 2010, 10:29 AM

Is it a good idea to config my lan whith the following commands?

/sbin/ifconfig eth0 11.0.1.41 netmask 255.0.0.0 broadcast 11.0.1.255
route add default gw 11.0.1.255 eth0

/sbin/ifconfig eth1 10.110.206.59 netmask 255.0.0.0 broadcast 10.110.206.255
route add default gw 10.110.206.12 eth1

/sbin/ifconfig eth2 172.16.3.108 netmask 255.255.0.0 broadcast 172.0.255.255

scott32746 · #10 28th January 2010, 12:33 PM

I would vi /etc/sysconfig/network-scripts/ifcfg-eth0 1 2 myself
Also check/set ONBOOT=yes ,, Do not copy ifcfg-ethX to others

madhavdiwan · #11 28th January 2010, 01:04 PM

NO

you are specifying the default gateway TWO times.. you can only do ONE default gateway route statement.
see your mistake in RED

/sbin/ifconfig eth0 11.0.1.41 netmask 255.0.0.0 broadcast 11.0.1.255
route add default gw 11.0.1.255 eth0

/sbin/ifconfig eth1 10.110.206.59 netmask 255.0.0.0 broadcast 10.110.206.255
route add default gw 10.110.206.12 eth1

See my previous post

guif83 · #12 28th January 2010, 03:48 PM

yes sorry i confuse.
I delete the content of ifcfg-eth0, ifcfg-eth1 and ifcfg-eth2 and i put in respective this information:

DEVICE=eth0
IPADDR=11.0.1.41
BROADCAST=11.0.1.255
NETMASK=255.255.255.0
NETWORK=11.0.1.0
ONBOOT=yes
GATEWAY=11.0.1.1
TYPE=Ethernet
BOOTPROTO=static

DEVICE=eth1
IPADDR=10.110.206.59
BROADCAST=10.110.206.255
NETMASK=255.255.255.0
ONBOOT=yes
TYPE=Ethernet
BOOTPROTO=static

DEVICE=eth2
IPADDR=172.16.3.108
BROADCAST=172.16.255.255
NETMASK=255.255.0.0
ONBOOT=yes
TYPE=Ethernet
BOOTPROTO=static

When i restart my network (service network restart), Fedora create a new interfaces!

scott32746 · #13 28th January 2010, 03:56 PM

You need to add HWADDR= to each
Easy way to get the info is to use command
#ifconfig
May need to ifconfig ethX up first
Without the correct HWADDR= you never connect

Here is what I have
EXAMPLE:

DEVICE=eth1
BOOTPROTO=none
DNS1=192.168.1.254
GATEWAY=192.168.1.254
HWADDR=00:14

1:17:32:B5
IPADDR=192.168.1.35
NETMASK=255.255.255.0
ONBOOT=yes
TYPE=Ethernet
IPV6INIT=no
USERCTL=no