[TriLUG] problems with multiple interfaces on a RHEL5.5 x64 machine

Tue Nov 8 19:39:28 EST 2011

I'm pinging by IP (eg 8.8.8.8).

The gateway has been set in /etc/sysconfig/network to be the same as is
handed-out by DHCP

Before setting eth1 to be static, it was on dhcp and the two interfaces
were getting sequential IPs (and with either up and the other down, we
could ping outside devices).

-WMM

On Tue, Nov 8, 2011 at 19:31, Matt Pusateri <mpusateri at wickedtrails.com>wrote:

> Heath is on track here most likely.  What does netstat -rn show when only
> eth1 is up versus when eth2 is up.  Also when you are pinging external IP's
> are you pinging by IP or by hostname?  If it's by hostname, I would suspect
> that your name servers are getting set in resolv.conf when you get an
> address via DHCP.
>
> Matt P.
>
> On Nov 8, 2011, at 7:28 PM, Heath Roberts wrote:
>
> > I don't know specifically about linux, but most unix distributions don't
> > like having multiple interfaces on the same subnet.
> >
> > As to why you have 'external' (by which I assume you mean off your own
> > subnet) connectivity with the DHCP address and not the static one: When
> you
> > have the DHCP interface active, it's learning routes (well, at least a
> > default route) from DHCP. How are you configuring routes when only the
> > static interface is up?
> >
> > On Tue, Nov 8, 2011 at 7:20 PM, Warren Myers <volcimaster at gmail.com>
> wrote:
> >
> >> Good evening, all
> >>
> >> I am trying to use a statically-assigned address on one interface
> (eth1) of
> >> a server and have a dhcp-assigned address on another interface (eth2) on
> >> the same subnet (172.17.11.0/24).
> >>
> >> When I setup a static IP for eth1 (following the directions found on
> >>
> >>
> http://www.cyberciti.biz/faq/rhel-centos-fedoracore-linux-network-card-configuration
> >> ),
> >> I entered the following into
> `/etc/sysconfig/network-scripts/ifcfg-eth1`:
> >>
> >> # ServerEngines Corp. Emulex OneConnect 10Gb NIC (be3)
> >> DEVICE=eth1
> >> BOOTPROTO=static
> >> DHCPCLASS=
> >> HWADDR=00:21:5A:9B:00:41
> >> IPADDR=172.17.11.203
> >> NETMASK=255.255.255.0
> >> #TYPE=ethernet
> >> ONBOOT=yes
> >>
> >>
> >> If eth1 is the only adapter running, I cannot ping *ANY* external IP :(
> >>
> >> When eth2 is also running, I can ping external addresses.
> >>
> >> `ifconfig` returns the following:
> >>
> >> eth1      Link encap:Ethernet  HWaddr 00:21:5A:9B:00:41
> >>         inet addr:172.17.11.203  Bcast:172.17.11.255  Mask:255.255.255.0
> >>         inet6 addr: fe80::221:5aff:fe9b:41/64 Scope:Link
> >>         UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
> >>         RX packets:4747 errors:0 dropped:0 overruns:0 frame:0
> >>         TX packets:5495 errors:0 dropped:0 overruns:0 carrier:0
> >>         collisions:0 txqueuelen:1000
> >>         RX bytes:447100 (436.6 KiB)  TX bytes:1059019 (1.0 MiB)
> >>         Memory:fbf60000-fbf80000
> >>
> >> eth2      Link encap:Ethernet  HWaddr 00:21:5A:9B:00:42
> >>         inet addr:172.17.11.245  Bcast:172.17.11.255  Mask:255.255.255.0
> >>         inet6 addr: fe80::221:5aff:fe9b:42/64 Scope:Link
> >>         UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
> >>         RX packets:6745 errors:0 dropped:0 overruns:0 frame:0
> >>         TX packets:10802 errors:0 dropped:0 overruns:0 carrier:0
> >>         collisions:0 txqueuelen:1000
> >>         RX bytes:1260318 (1.2 MiB)  TX bytes:12302950 (11.7 MiB)
> >>         Memory:fbe40000-fbe60000
> >>
> >>
> >> # cat /etc/sysconfig/network
> >> HOSTNAME=<redacted>
> >> NETWORKING=yes
> >> NETWORKING_IPV6=no
> >> GATEWAY=172.17.11.1
> >>
> >>
> >> Am I missing something super obvious? If so, what is it?
> >>
> >> Regards,
> >> Warren
> >>
> >> --
> >> Warren Myers
> >> http://warrenmyers.com
> >> http://twitter.com/volcimaster
> >> http://www.linkedin.com/in/warrenmyers
> >> --
> >> This message was sent to: Heath Roberts <htroberts at gmail.com>
> >> To unsubscribe, send a blank message to trilug-leave at trilug.org from
> that
> >> address.
> >> TriLUG mailing list : http://www.trilug.org/mailman/listinfo/trilug
> >> Unsubscribe or edit options on the web  :
> >> http://www.trilug.org/mailman/options/trilug/htroberts%40gmail.com
> >> TriLUG FAQ          :
> >> http://www.trilug.org/wiki/Frequently_Asked_Questions
> >>
> >
> >
> >
> > --
> > Heath Roberts
> > htroberts at gmail.com
> > --
> > This message was sent to: M. Pusateri <mpusateri at wickedtrails.com>
> > To unsubscribe, send a blank message to trilug-leave at trilug.org from
> that address.
> > TriLUG mailing list : http://www.trilug.org/mailman/listinfo/trilug
> > Unsubscribe or edit options on the web        :
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> > TriLUG FAQ          :
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>
> --
> This message was sent to: Warren <volcimaster at gmail.com>
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> address.
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>

-- 
Warren Myers
http://warrenmyers.com
http://twitter.com/volcimaster
http://www.linkedin.com/in/warrenmyers