Gentlemen,
I have stopped the machine, removed the second ethernet card, rebooted and in that process, through kudzu, removed the configuration for the removed card. After system is up, I have verified that the configuration files for card two are removed. I am now back to where I was after having tried, for several hours, to get eth0 to talk to the switch. The green lights are on at either and, the cable check on the switch shows cable OK. The computer can talk to the other computers/devices on the local network but cannot even ping the switch. I am logged into the computer from my laptop (using ssh) and it works fine.
The 'netstat -rn' output is now;
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth0
and 'ifconfig' is;
eth0 Link encap:Ethernet HWaddr 00:0F:EA:5C:06:CF
inet addr:192.168.0.90 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:785 errors:0 dropped:0 overruns:0 frame:0
TX packets:269 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:231079 (225.6 KiB) TX bytes:27185 (26.5 KiB)
Interrupt:201 Base address:0xc000What is so strange, is that the computer can talk to all local addresses except the switch (192.168.0.1) and two other computers on the local network can talk to it, all obviously through the switch both ways. This shows that the cabling is OK, and that the problem is probably in the routing on the computer (not allowing it to connect directly to the switch) or in the switch, not accepting communication from the computer. The switch routes properly for the other computers on the network and can be managed from either one (tested) but not from the problem child. If I change the configuration on the computer to use DHCP (and rebooting) the computer does not get (receive/accept) the DHCP configuration and is thus 'dead', i.e. no communication to nor from any computer. Therefore, until the communication to/from the switch is OK I am using a static address. To eliminate hardware faults possible in the ethernet port on the motherboard (eth0) I installed a network card, tested to perform OK in another computer, and disabled the motherboard port using the BIOS. With only an expansion ethernet card active in the computer I made the same tests with the same results. This seems to eliminate network card problem in the computer. My current setup is, as per the first paragraph above, motherboard ethernet port only with static address. Still no joy. I am at a loss.
Regards, Mats
Rick Stevens wrote:
Mats Erlandson wrote:
Well, I did what you suggested, but, to no avail. The result is still the same. By the way, the reason I put in the second card was to be able to switch between two, which I already tried without success. The vexing question is though that if I configure one or both of the network interfaces for DHCP neither one picks up the DHCP info. This works flawlessly on both the other computers.
So, this new computer cannot communicate with the switch or the wide area network through the switch, but, mysteriously, it can communicate with other computers/devices on the local area network routed through the switch.
A feeling is that the switch is at fault. However, the hardwired working computer does not mind a port switch on the router, it just works, also after reboot. The switch must have taken a serious dislike to the new computer :-).
The trick is that you only want ONE NIC. Your routes are confused. In general, there should only be ONE route for each network and you had two. There should also only be one default route (shown as "UG" in the "flags" column of the "netstat -rn" listing).
You should also keep in mind that what you think is eth0 may be eth1 and vice versa. Generally, the NIC furthest from the CPU in your motherboard is eth0, but not always (it depends on how the PCI bus probes out). If your motherboard has a built-in NIC, then it's usually eth0.
I'd recommend you delete the file
/etc/sysconfig/network-scripts/ifcfg-eth1
Then edit the file
/etc/sysconfig/network-scripts/ifcfg-eth0
Since you will be using DHCP, you only need the following information in it:
DEVICE=eth0 ONBOOT=yes BOOTPROTO=dhcp
Also edit the "/etc/sysconfig/network" file and make sure you do NOT have a "GATEWAY=" line in it (your DHCP server will provide one).
Next, enter the two commands:
/etc/rc.d/init.d/network stop /etc/rc.d/init.d/network start
Verify that you have a link between eth0 and your hub/switch/router (they should both have a green LED showing). The cable on the other NIC should be unplugged, just so you don't get confused.
Once that's done, verify that eth0 came up and got an IP address:
ifconfig eth0
You can also verify that the default route got set up. "netstat -rn" should only show a couple of lines. The "device" column should only have "eth0" in it. If "eth1" shows up, we have other issues.
You should also check the contents of the "/var/log/messages" file as well as the output of the "dmesg" command to see if you're getting errors on the system setup.
As far as "switching" NICs, I assume you mean as a failover method. Doing that manually is not necessarily a good idea. You'd need to bring down the "failed" NIC, destroy existing routes, purge ARP tables, then bring up the second NIC and wait for it to build routes. You can't do it "on the fly".
There is a mechanism called "bonding" that allows you to tie the two NICs into a failover service. Linux has a bonding driver, but to make it work the hub/switch/router must also support support bonding. Very few (if any) SOHO (small home or office) units out there (e.g. D-Link, Linksys, AirLink) do. You'd need to go to a relatively high-end switch (3Com, Cisco, Extreme or HP) to get bonding support--and even then it's not that reliable (at least not on HP or 3Com) in my experience. ---------------------------------------------------------------------- - Rick Stevens, Senior Systems Engineer rstevens@xxxxxxxxxxxxxxx - - VitalStream, Inc. http://www.vitalstream.com - - - - Tempt not the dragons of fate, since thou art crunchy and taste - - good with ketchup. - ----------------------------------------------------------------------
