Thanks for the responses. Please see my answers to your questions: 1) What I want is to locate exactly where the psuedo IF and get rid of it. Is there a way to prohibit the pseduo IF not to get DHCP answer? 2) Output of Ifconfig -a: ########################################## eth0 Link encap:Ethernet HWaddr E4:1F:13:77:16:5F inet addr:10.1.10.10 Bcast:10.1.10.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:7818 errors:0 dropped:0 overruns:0 frame:0 TX packets:7762 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:841003 (821.2 KiB) TX bytes:1095188 (1.0 MiB) Interrupt:169 Memory:e8100000-e8110000 eth1 Link encap:Ethernet HWaddr E4:1F:13:77:16:60 BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) Interrupt:50 Memory:e8200000-e8210000 eth2 Link encap:Ethernet HWaddr 00:15:17:EB:AE:A4 BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) Memory:e8020000-e8040000 eth3 Link encap:Ethernet HWaddr 00:15:17:EB:AE:A5 BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) Memory:e8060000-e8080000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:11040 errors:0 dropped:0 overruns:0 frame:0 TX packets:11040 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:2731896 (2.6 MiB) TX bytes:2731896 (2.6 MiB) ########################################### Output on Switch: ###################################################### SW#sh arp Protocol Address Age (min) Hardware Addr Type Interface Internet 10.1.10.1 - 0022.0c4d.c141 ARPA Vlan10 Internet 10.1.10.3 5 e41f.1377.1661 ARPA Vlan10 >>>>Psuedo Interface off Eth0 Internet 10.1.10.10 5 e41f.1377.165f ARPA Vlan10 SW#sh ip dhcp binding IP address Client-ID/ Lease expiration Type Hardware address 10.1.10.3 e41f.1377.1661 Mar 06 1993 10:22 AM Automatic >>>>Psuedo Interface acquiring DHCP IP Address 10.1.30.57 0100.2713.6521.9c Mar 06 1993 10:03 AM Automatic SW#ping 10.1.10.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.10.3, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 33/37/51 ms SW#ping 10.1.10.10 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.1.10.10, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/9 ms ###################################################### 3) No Virtual machine is running on this box. 4) Have you checked if your motherboard IPMI is not pulling an address during boot? -- Frankly, not sure how to check motherboard IPMI messages. Verified dmesg output. Following is the dmesg output. Please share any way to check motherboard IPMI is pulling another address? dmesg output: (showing only eth0/eth1/eth2 output) ######################################################################### EDAC MC: Ver: 2.0.1 Apr 2 2010 EDAC MC0: Giving out device to i3200_edac i3200: DEV 0000:00:00.0 e1000e: Intel(R) PRO/1000 Network Driver - 1.0.2-k3 e1000e: Copyright (c) 1999-2008 Intel Corporation. ACPI: PCI Interrupt 0000:04:00.0[A] -> GSI 16 (level, low) -> IRQ 169 PCI: Setting latency timer of device 0000:04:00.0 to 64 eth0: (PCI Express:2.5GB/s:Width x4) 00:15:17:eb:ae:a4 eth0: Intel(R) PRO/1000 Network Connection eth0: MAC: 0, PHY: 4, PBA No: d56146-003 ACPI: PCI Interrupt 0000:04:00.1[B] -> GSI 17 (level, low) -> IRQ 209 PCI: Setting latency timer of device 0000:04:00.1 to 64 sd 0:0:0:0: Attached scsi generic sg0 type 0 sd 1:0:0:0: Attached scsi generic sg1 type 0 scsi 2:0:0:0: Attached scsi generic sg2 type 5 eth1: (PCI Express:2.5GB/s:Width x4) 00:15:17:eb:ae:a5 eth1: Intel(R) PRO/1000 Network Connection eth1: MAC: 0, PHY: 4, PBA No: d56146-003 tg3.c:v3.106 (January 12, 2010) PCI: Enabling device 0000:00:1f.3 (0141 -> 0143) ACPI: PCI Interrupt 0000:00:1f.3[B] -> GSI 17 (level, low) -> IRQ 209 ACPI: PCI Interrupt 0000:02:00.0[A] -> GSI 16 (level, low) -> IRQ 169 PCI: Setting latency timer of device 0000:02:00.0 to 64 eth2: Tigon3 [partno(BCM95722) rev a200 PHY(5722/5756)] (PCI Express) 10/100/1000Base-T Ethernet e4:1f:13:77:16:5f eth2: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[1] WireSpeed[1] TSOcap[1] eth2: dma_rwctrl[76180000] dma_mask[64-bit] ACPI: PCI Interrupt 0000:03:01.0[A] -> GSI 21 (level, low) -> IRQ 50 eth1: Tigon3 [partno(BCM95703A30) rev 1100 PHY(5703)] (PCI:33MHz:32-bit) 10/100/1000Base-T Ethernet e4:1f:13:77:16:60 eth1: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[0] WireSpeed[1] TSOcap[1] eth1: dma_rwctrl[763f0000] dma_mask[64-bit] sr0: scsi3-mmc drive: 24x/24x writer cd/rw xa/form2 cdda tray Uniform CD-ROM driver Revision: 3.20 ######################################################################### Regards, Sri On Wed, Apr 11, 2012 at 4:05 PM, sri <bskmohan at gmail.com> wrote: > Group, > > My linux box, running with Centos-5.5, is showing up (??) a pseudo > network interface for Eth0. > On Switch where my Eth0 is connected, observed 2 MAC-Addresses. > If a DHCP server present in LAN, the second pseudo interface is > picking up a DHCP IP Address too. > Furthermore you can ping both Eth0 ip and Psedo Eth0 IP from the switch. > The intensity of the problem is more when port-security is configured > on SW for that port. > > “ifconfig –a” is not showing that pseudo interface. > From dmesg output, no new things observed related while detecting the > eth0 NIC during bootup. > Only proof for this pseudo inerface’s mac address is SW showing it (on > the SW port connected to my box eth0) in “show mac address-table” > output > > Is there anything that I have to check to nail down the issue. > > Any pointers are highly appreciated. > > > -- > -- > Krishna Mohan B -- -- Krishna Mohan B