Linux – Bonding and default gateway problem (CentOS)

bondingcentoslinuxnetworking

I configured network bonding on two machine with centos 5.5.
Bonding works well, but the problem is default gateway: it is not configured!

I follow this tutorial.
I added GATEWAY in both (and either) /etc/sysconfig/network and /etc/sysconfig/network-scripts/ifcfg-bond0.
But, when I restart network (or server) there is no default gateway (route command).

This is ip route ls output after network restart:

10.0.0.0/16 dev bond0 proto kernel scope link src 10.0.0.88

Where is my mistake?

/etc/sysconfig/network
NETWORKING=yes
NETWORKING_IPV6=no
IPV6INIT=no
HOSTNAME=mysql2
NOZEROCONF=yes
GATEWAY=10.0.1.10

/etc/sysconfig/network-scripts/ifcfg-bond0 
DEVICE=bond0
IPADDR=10.0.0.88
NETMASK=255.255.0.0
NETWORK=10.0.0.0/16
BROADCAST=10.0.255.255
GATEWAY=10.0.1.10
ONBOOT=yes
BOOTPROTO=none
USERCTL=no
TYPE=Ethernet

/etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=none
USERCTL=no
MASTER=bond0
SLAVE=yes

/etc/sysconfig/network-scripts/ifcfg-eth1
DEVICE=eth1
ONBOOT=yes
BOOTPROTO=none
USERCTL=no
MASTER=bond0
SLAVE=yes

Best Answer

NETWORK=10.0.0.0/16

I don't think this is specified correctly. It should be just

NETWORK=10.0.0.0

or try leaving it out entirely its redundant information

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Centos – Trixbox CentOS Default GW Problem (Multi-homed server)

In the end, the issue ended up being that the default gateway was not in fact on the same subnet!

Once I changed the gateway to a router on the same subnet (and removed all instances of GATEWAY from the configuration files /etc/sysconfig/network-scripts/ifcfg-eth*), exclusively the GATEWAY/GATEWAYDEV entries in the /etc/sysconfig/network

I was able to restart the networking service and access the internet.

Centos – the correct way to setup a bonded bridge on Centos 6 for KVM guests

Not sure about CentOS 6, but on Fedora the bonding module is not added to the Linux kernel by default and therefore you need to create a file /etc/modprobe.d/bonding.conf with content

alias bond0 bonding

Reboot, and you should see bonding module loaded during boot.

Since you have two bonded interfaces you might have to add another alias line for bond1 as well. However I have never tried that.

Suggest you get one working and then worry about setting up the second.

Other issue you raised about the bridge, other points to note, these configurations work with the network daemon but I don't believe they work with NetworkManager. Are you running the network or the NetworkManager daemon?

And finally, there are different ways to configure netfilter to handle bridged interfaces. At least on Fedora 12+, the default is to disable netfilter on bridges. However you can change this by editing /etc/sysctl.conf and setting

net.bridge.bridge-nf-call-iptables=1

Do the same for arp and ipv6 and in this file you also need to set

net.ipv4.ip_forward=1

Flush your FORWARD chain and replace with iptables rule

iptables -A FORWARD -m physdev --physdev-is-bridged -j ACCEPT

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