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I have a system with two NICs with 4 ip addresses (eth0,1,2,3) on two different subnets (x.x.230.x and x.x.221.x).

Problem when our network Engineer shuts down one switch port, 2 ip's on same subnet will go down.

I am trying to setup these for redundancy if one of the ip's or switches go down, other will take over. I tried with different options with zoning and port forwarding, but it is not wotking for me.

My NICs are configured as follows:

eth0-x.x.230.16  int zone vlan1
eth1-x.x.221.1   ext.zone vlan2
eth2-x.x.230.26  int zone vlan1  
eth3-x.x.221.11  ext.zone vlan2

I know it's possible to configure these NICs for redundancy - What am I missing?

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I cleaned up the formatting of your question, but can you clarify: Do you have two or four physical NICs? (it looks like four - eth0, eth1, eth2, eth3) in which case NoNoNo's answer should work for you. If you have two physical NICs you also need to configure your server to understand the vlan setup you have. –  voretaq7 May 16 '12 at 21:01
    
4 ip's on 2 network cards internal and external zone –  Mike May 16 '12 at 21:19
    
OK, so then the gist of NoNoNo's answer holds, but you need to put each NIC into both VLANs, and then configure bonding as necessary for redundancy. –  voretaq7 May 16 '12 at 21:48

1 Answer 1

If you want redundancy you need to use bonding for each pair of NICs connected to the same subnet.
Documentation on setting up bonding can be found at http://www.novell.com/communities/node/6626/bonding-multiple-network-interfaces-sles-10

If you want obtain redundancy but not more throughput you would configure bonding with mode=1.
In order to obtain a configuration without a single point of failure you would obviously need two switches, with each NIC in the pair connected to a different switch.

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Hi,I do have 2 switches for complete redundancy.But I thought i do not need bonding setup. So what you are saying, there is no other way to setup these functions without bonding? –  Mike May 16 '12 at 20:58
    
@Mike In order to have failover redundancy between the NICs you need to set up bonding, otherwise when a switch port goes down there's nothing on the Linux side that handles the failure, and you lose whatever IPs are associated with the downed port. Bonding or something equivalent to it like CARP is what takes care of advertising the IP(s) on the alternate NIC. –  voretaq7 May 16 '12 at 21:04

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