Secondary NIC installed, but all traffic coming through primary NIC

Reado

Well-Known Member
Sep 8, 2009
225
8
68
United Kingdom
cPanel Access Level
Root Administrator
I have a Xen VM running CentOS 5.6 x64 w/ cPanel-CURRENT. The network configuration is as follows:

Code:
NIC0 (ba-ff-ca-1c-fd-9a): 10.1.1.116
NIC1 (22-43-73-91-bb-10): 10.1.1.115
Both IPs can be pinged outside the server from a Windows 7 workstation. However when I run "arp -a" it says:

Code:
10.1.1.115            ba-ff-ca-1c-fd-9a     dynamic
10.1.1.116            ba-ff-ca-1c-fd-9a     dynamic
So even though each IP is bound to a different NIC and MAC address on the server and this is what XenServer sees, Windows reckons both IPs are bound to NIC0.

As another test, I disabled NIC0 on the XenServer itself and then tried pinging 10.1.1.115 again but it timed out.

Here's the output from ifconfig:

Code:
[email protected] [/tmp/selfextract.8]# ifconfig
eth0      Link encap:Ethernet  HWaddr BA:FF:CA:1C:FD:9A
          inet addr:10.1.1.116  Bcast:10.1.1.255  Mask:255.255.255.0
          inet6 addr: fe80::b8ff:caff:fe1c:fd9a/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:7980806 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1245247 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:10751839414 (10.0 GiB)  TX bytes:1750474802 (1.6 GiB)

eth1      Link encap:Ethernet  HWaddr 22:43:73:91:BB:10
          inet addr:10.1.1.115  Bcast:10.1.1.255  Mask:255.255.255.0
          inet6 addr: fe80::2043:73ff:fe91:bb10/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:38196 errors:0 dropped:0 overruns:0 frame:0
          TX packets:352 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:5375064 (5.1 MiB)  TX bytes:15000 (14.6 KiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:13257 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13257 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:1803199 (1.7 MiB)  TX bytes:1803199 (1.7 MiB)

[email protected] [/tmp/selfextract.8]#
Does anyone know what could be causing this? Any help would be greatly appreciated.
 

Reado

Well-Known Member
Sep 8, 2009
225
8
68
United Kingdom
cPanel Access Level
Root Administrator
Thanks, just tried that, changed it to eth1 then tried arp -a again but both IPs were still using the same MAC.

Under WHM > IP unctions > Show or Delete Current IP Addresses, it says 10.1.1.115 is assigned to eth1. I tried removing the IP via WHM but it says it failed to remove the IP address, even though no sites are using it?
 

Reado

Well-Known Member
Sep 8, 2009
225
8
68
United Kingdom
cPanel Access Level
Root Administrator
I just tried removing eth1 from the VM and rebooting. After the reboot, cPanel said the following:

Code:
10.1.1.115 	eth0:cp1
10.1.1.116 [Main Address]
Main/shared IP for root 	eth0
Is it normal for cPanel to re-assign IPs to another NIC if the other NIC is removed? Or is it likely that eth0:cp1 was always there?