Network issues

MarcusWebb1966 · 01-18-2012, 06:32 AM

Hi

Last night when we rebooted one of our servers, the main network eth0 came up on the allocated IP address but the other addresses that should have come up did not do so. I'm trying to understand why.

As a result, I'm concerned that the interfaces file may not be set up properly.

Code:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0 eth0:2 eth0:6
iface eth0 inet static
        address x.y.36.15
        netmask 255.255.254.0
        network x.y.36.0
        broadcast 255.255.254.0
        gateway x.y.36.4
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers n.o.p.q   r.s.t.u

iface eth0:2 inet static
        address x.y.36.215
        netmask 255.255.254.0
        network x.y.36.0

iface eth0:6 inet static
        address x.y.37.124
        netmask 255.255.254.0
        network x.y.36.0
#

If this is right (and having booted the server on a couple of occasions previously, I see no reason for it not to be), I should get:

eth0: - x.y.36.15
eth0:6 - x.y.36.215
eth0:2 - x.y.37.124

Is this assertion correct?

Also having looked through syslog, messages, dmesg, and a couple of other files, I can't see anything obvious and am beginning to think that the server just "froze". Any other ideas of where to look would be gratefully received.

Dutch Master · 01-18-2012, 07:07 AM

Have you tried bringing up the eth0:2 and :6 ifaces manually? If that works, you'd narrow the issue down to the boot scripts, if it doesn't, it'll give you errors that'll point you in the right direction

larrym82 · 01-18-2012, 07:12 AM

Quote:

Originally Posted by MarcusWebb1966

Hi

Last night when we rebooted one of our servers, the main network eth0 came up on the allocated IP address but the other addresses that should have come up did not do so. I'm trying to understand why.

As a result, I'm concerned that the interfaces file may not be set up properly.

Code:

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0 eth0:2 eth0:6
iface eth0 inet static
        address x.y.36.15
        netmask 255.255.254.0
        network x.y.36.0
        broadcast 255.255.254.0
        gateway x.y.36.4
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers n.o.p.q   r.s.t.u

iface eth0:2 inet static
        address x.y.36.215
        netmask 255.255.254.0
        network x.y.36.0

iface eth0:6 inet static
        address x.y.37.124
        netmask 255.255.254.0
        network x.y.36.0
#

If this is right (and having booted the server on a couple of occasions previously, I see no reason for it not to be), I should get:

eth0: - x.y.36.15
eth0:6 - x.y.36.215
eth0:2 - x.y.37.124

Is this assertion correct?

Also having looked through syslog, messages, dmesg, and a couple of other files, I can't see anything obvious and am beginning to think that the server just "froze". Any other ideas of where to look would be gratefully received.

It's been awhile, so take this with a grain of proverbial salt. Your network mask essentially assigns all of your A level traffic to network 254, but your level A IP addresses are for 36 or 37. 255 is a broadcast address, but 254 is a specific network address. So, your private network would have to be masked as 255.255.255.0 in order to use addresses 255.255.0.0 to 255.255.254.254 inclusive. The way you have it set up you get addresses from 255.255.254.0 to 255.255.254.254 inclusive. 0 is always a local address.