Problem with dual NICs

[dblaszczyk]

I setup a mail server using Fedora Core 5 and have one NIC on the motherboard and one extra NIC installed in a pci slot. I have assigned a seperate ip address to each NIC:

eth0 192.168.1.202
eth1 192.168.1.200

When i have both plugged in i am able to use it perfectly, but when i unplug eth1 i can still reach both ip addresses and when i unplug eth0 i am unable to reach either. My hope was that if one of them was unplugged i would still be able to reach the other. Anyone know what i could be doing wrong?

[SlowJet]

You are doing this as a redundent network?

This is the same sub net so you have etho as the real connection and eth1 is not doing anything.

When you unplug eth1, the system does not care because it was never being used.

When you unplug eth o, the connection is down, and eth1 is still not doing anything.


What do these 2 nic's connect to?

SJ

[David Becker]

Originally Posted by dblaszczyk

I setup a mail server using Fedora Core 5 and have one NIC on the motherboard and one extra NIC installed in a pci slot. I have assigned a seperate ip address to each NIC:

eth0 192.168.1.202
eth1 192.168.1.200

You could be having overlapping networks. What network and broadcast are you using for these devices?

ifconfig
netstat -nr

David

[dblaszczyk]

@SlowJet: I am not sure what you mean by "What do these 2 nic's connect?" But yes i am experimenting with a redundant physical connection for a server.

@David Becker: I am new to this so im not sure which part of those two commands i am supposed to look for so i copied what was returned from those two commands.

Thanks for the quick responses.

netstat -nr:

Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
0.0.0.0 192.168.1.254 0.0.0.0 UG 0 0 0 eth0

ifconfig:

eth0 Link encap:Ethernet HWaddr 00:14:2A:B4:A7:14
inet addr:192.168.1.202 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::214:2aff:feb4:a714/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:925 errors:0 dropped:0 overruns:0 frame:0
TX packets:905 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:385352 (376.3 KiB) TX bytes:164627 (160.7 KiB)
Interrupt:16 Base address:0xe800

eth1 Link encap:Ethernet HWaddr 00:0AD:11:4E3
inet addr:192.168.1.200 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::20a:cdff:fe11:4ed3/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:125 errors:0 dropped:0 overruns:0 frame:0
TX packets:32 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:11671 (11.3 KiB) TX bytes:3521 (3.4 KiB)
Interrupt:18 Base address:0x2000

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:2336 errors:0 dropped:0 overruns:0 frame:0
TX packets:2336 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:3910665 (3.7 MiB) TX bytes:3910665 (3.7 MiB)

[stdcpm14]

You're looking for Nic Teaming (Bonding)

I used this to set mine up:

http://www.cyberciti.biz/nixcraft/vi...le-network.php

[dblaszczyk]

Originally Posted by stdcpm14

You're looking for Nic Teaming (Bonding)

I used this to set mine up:

http://www.cyberciti.biz/nixcraft/vi...le-network.php

Thats not exactly what i am looking for as i want the nics to each have its own ip address so they operate as to seperate connections. Thanks for the link though, that is another good thing to know.

[dblaszczyk]

Originally Posted by SlowJet

You are doing this as a redundent network?

This is the same sub net so you have etho as the real connection and eth1 is not doing anything.

When you unplug eth1, the system does not care because it was never being used.

When you unplug eth o, the connection is down, and eth1 is still not doing anything.


What do these 2 nic's connect to?

SJ

I didnt get what you were saying at first but i figured it out and I put one of the nics on a different subnet and it works now so thanks for the suggestion!

[Iron_Mike]

Originally Posted by dblaszczyk

I setup a mail server using Fedora Core 5 and have one NIC on the motherboard and one extra NIC installed in a pci slot. I have assigned a seperate ip address to each NIC:

eth0 192.168.1.202
eth1 192.168.1.200

When i have both plugged in i am able to use it perfectly, but when i unplug eth1 i can still reach both ip addresses and when i unplug eth0 i am unable to reach either. My hope was that if one of them was unplugged i would still be able to reach the other. Anyone know what i could be doing wrong?

You're not doing anything wrong this is perfectly sane. Think about it, 2 Nics connected with cabling to some hub, switch, whatever. You unplug NIC 1 and expect to hit NIC 2, at the hardware layer, think about that for a sec. Does that seem like a security issue. If you set the NICs up for bonding it is possible, but it almost seems that you want like a pop address using 1 nic and smtp using the other nic??? or inbound and outbound mail using different nics.