Need some help with my network config

[ovizii]

Due to my EFA box running on OVH hosting which has a weird setup: http://help.ovh.co.uk/BridgeClient#link4 I couldn't enter my IP/GATEWAY through the GUI but had to manually edit it as the GW is outside the network.

Now all is running well but I have some doubts about my config. According to my host, I need to use my failover IPs as single IPs with a /32 network in order to use the complete block of 16.

here is my current /etc/sysconfig/network-scripts/ifcfg-eth0

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DEVICE="eth0"
BOOTPROTO="none"
ONBOOT="yes"
BROADCAST=51.xxx.xxx.255
NETWORK=51.xxx.xxx.0
NETMASK="255.255.255.0"
IPADDR="51.xxx.xxx.92"

and my File: /etc/sysconfig/network

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NETWORKING=yes
HOSTNAME=jacob.mydomain.za
GATEWAY=94.xxx.xxx.254
GATEWAY=94.xxx.xxx.254
GATEWAY=94.xxx.xxx.254
GATEWAY=94.xxx.xxx.254
GATEWAY=94.xxx.xxx.254

Now networking isn't my forte so can someone help "fix" this so I am using 255.255.255.255 as my netmask? Also not sure why I have the same gateway repeated 5x in the second config file
I am asking for help because this is live so I cannot do random test to figure it out.

[darky83]

No experience with OVH in a setup like this.

But the extra gateway's can be removed anyhow, just 1 is read by the systems so keep one and remove the others.

If I read the OVH page correctly they want you to set A /32 and force the gateway in a route map, but I find it weird that your IP starts with 51 and that your gateway would start with 94.. But if what you show is correct it would be something like below

Maybe someone with more OVH knowledge can confirm this, as i'm not 100% sure.
If you can't test this and it works now I would suggest to stay off it and try to find a way to get an efa test machine deployed so you can do some tests first (and share your experience )

/etc/sysconfig/network-scripts/ifcfg-eth0

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DEVICE="eth0"
BOOTPROTO="none"
ONBOOT="yes"
NETMASK="255.255.255.255"
IPADDR="51.xxx.xxx.92"
GATEWAY=94.xxx.xxx.254

/etc/sysconfig/network-scripts/route-eth0

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94.xxx.xxx.254 dev eth0
default via 94.xxx.xxx.254 dev eth0

and remove the gateway from the original file /etc/sysconfig/network

[ovizii]

Thanks for the reply.

If I read the OVH page correctly they want you to set A /32 and force the gateway in a route map, but I find it weird that your IP starts with 51 and that your gateway would start with 94

this is exactly right and leads to loads of problems as the gateway is never in the same network as the extra IPs you get so most distros complain that they cannot set that GW so I always end up setting it manually via config files.

/etc/sysconfig/network-scripts/route-eth0

I did have those routes in there, forgot to mention it.

I'll see if anyone can add more info but basically I think you and I have grasped the specifics of OVH.
I just don't know enough about networking hence my question here.

So if someone with more knowledge about networking can confirm I guess I'll give it a test late at night soon.

I wasn't sure about these 3 entries, whether they are needed or how to change them as they are currently working like this.

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BROADCAST=51.xxx.xxx.255
NETWORK=51.xxx.xxx.0
NETMASK="255.255.255.0"

[darky83]

the BROADCAST and NETWORK items can be removed, they are not really necessary (actually I never configure those on any of my linux boxes)

for a /32 subnet (host only) the netmask should be 255.255.255.255.

But I find this configuration weird, but googling a bit it seems lots and lots of users of OVH or So you Start fight with the same issue.
It is not really a networking question but more an specific OVH item as they have done something 'weird'

If I read it correctly you can even have these IPs available on multiple servers, no matter in what kind of IP subnet you are, so i'm guessing they use some kind of arp trick/rules/scripts to force an IP in their routers to a specific MAC address, thus there is no need for a subnet.

[ovizii]

@darky83: you're spot-on and thanks for the additional info. I'll give it a try one of these weekends. Will update the thread once I have tested it.

[jahanjoon]

I've got a couple of EFAs running on OVH/SYS. The network config is indeed a little nutty on OVH/SYS but it seems to work without issue (I think I've just tempted fate). This one is running on Proxmox and works absolutely fine. Am happy to help, just drop me a pm or reply here. All the best.

/etc/sysconfig/network-scripts/ifcfg-eth0

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DEVICE=eth0
BOOTPROTO=none
ONBOOT=yes
IPADDR=178.xxx.xxx.43
NETMASK=255.255.255.255
NETWORK=178.xxx.xxx.43
BROADCAST=178.xxx.xxx.43

/etc/sysconfig/network-scripts/route-eth0

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94.xxx.xxx.254 dev eth0
default via 94.xxx.xxx.254 dev eth0

/etc/sysconfig/network

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NETWORKING=yes
HOSTNAME=mxa.domain.com
GATEWAY=94.xxx.xxx.254

[ovizii]

@jahanjoon: thanks, your example seems to have worked for me (adapted to my IP of course)