Noticed in my /var/log/messages 2

[eanda10]

I noticed the following lines in my /var/log/messages is it somthing I should be concerned about? and what might be causing or how can I narrow down what might be causing it?

my OS = RH8.0
this machine is my mailserver running qmail
and there is nothing in my cron runnig @ this time.


Sep 1 05:26:28 mail kernel: e1000: eth0 NIC Link is Down
Sep 1 05:26:32 mail kernel: e1000: eth0 NIC Link is Up 100 Mbps Full Duplex
Sep 1 05:26:33 mail kernel: e1000: eth0 NIC Link is Down
Sep 1 05:26:37 mail kernel: e1000: eth0 NIC Link is Up 100 Mbps Full Duplex
Sep 1 05:26:45 mail kernel: e1000: eth0 NIC Link is Down
Sep 1 05:26:49 mail kernel: e1000: eth0 NIC Link is Up 100 Mbps Full Duplex
Sep 1 05:26:59 mail kernel: e1000: eth0 NIC Link is Down
Sep 1 05:27:03 mail kernel: e1000: eth0 NIC Link is Up 100 Mbps Full Duplex
Sep 1 05:27:05 mail kernel: e1000: eth0 NIC Link is Down
Sep 1 05:27:07 mail kernel: e1000: eth0 NIC Link is Up 100 Mbps Full Duplex
Sep 1 05:27:07 mail kernel: e1000: eth0 NIC Link is Down
Sep 1 05:27:10 mail kernel: e1000: eth0 NIC Link is Up 100 Mbps Full Duplex

 

[sleipnir214]

I'd first try replacing the network cable.

Want the best answers? Ask the best questions:

http://www.catb.org/~esr/faqs/smart-questions.html

TANSTAAFL!!

 

[blockhole]

may be its your network card (NIC) try replacing it. i experiance it before and indeed network card is the problem. hope its the same case with you.

 

[ProudToBeLeeds]

Best way to check your NIC is to ping 127.0.0.1 Simple as.


Have you tried using it as a half duplex connection?

 

[danielhozac]

Pinging 127.0.0.1 will work regardless of whether the NIC works or not. You can successfully ping 127.0.0.1 even if you don't have a NIC in the computer.

//Daniel

 

[ProudToBeLeeds]

"Pinging 127.0.0.1 will work regardless of whether the NIC works or not. You can successfully ping 127.0.0.1 even if you don't have a NIC in the computer. "



err no actaully you can't. Try it, or infact bring down lo0 and try to ping 127.0.0.1



# ifconfig lo0 down
# ping 127.0.0.1
^C#

 

[danielhozac]

Of course you can't ping 127.0.0.1 if you bring down the loopback inteface. Bring down your ethernet interface and try it:

[daniel@krypton daniel]$ sudo /sbin/ifconfig eth0 down
[daniel@krypton daniel]$ ping 127.0.0.1
PING 127.0.0.1 (127.0.0.1) from 127.0.0.1 : 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.042 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.029 ms
64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.028 ms

--- 127.0.0.1 ping statistics ---
3 packets transmitted, 3 received, 0% loss, time 1998ms
rtt min/avg/max/mdev = 0.028/0.033/0.042/0.006 ms

//Daniel

 

[ProudToBeLeeds]

AH the ethernet one is different.

Say for example you have a user that has reported lack of network connectivity. Now no one else in the department they are in are reporting any problems. So, the first thing you do is ping 127.0.0.1 which is the loopback address or the NIC to see if it works. IF it doesn't and the cable is plugged and everything else if OK what does this tell you??? It tells you the NIC is kaput. Simple as!


Cheers

Steve

SCSA,SCNA,CCIE

 

[ProudToBeLeeds]

True it could be the OS or an app but in most cases its a faulty NIC. However the point was that you cannot ping 127.0.0.1 if the machine has no NIC. Turning off lo0 is basically the same as pulling the bugger out.

 

[danielhozac]

No it's not. The loopback interface has _nothing_ to do with the NIC. Pull your NIC out, start the computer and you'll see that you can ping 127.0.0.1.

//Daniel

 

[ProudToBeLeeds]

Quick lesson.


Applications (eg. ftp, web browser, e-mail transports)
|
| Applications use a common API to talk to the
| TCP/IP stack - commonly called 'sockets' interface
| or BSD sockets. These are the Socket_ SWIs provided
| by the FreeNet module or the Internet module (or
| the NetLib library which is a veneer to those SWIs
|
TCP/IP stack (eg. FreeNet module, Internet module)
|
/|\ The stack uses the DCI interface to talk to the
/ | \ network interfaces. There may be any number of these
/ | \ loaded at any time. In this diagram eb0 represents
.---' | `---. the EtherB ethernet interface card; sl0 represents
| | | the SLIP driver; lo0 represends the loopback driver
eb0 sl0 lo0 .other examples include
ppp0 (the PPP driver)

 

[danielhozac]

Point being? Your schematic sketch only confirms what I've been saying all along, the loopback interface is completely unrelated to other network interfaces.

//Daniel

 

[blockhole]

why ping the loopback (127.0.0.1)address in checking NICs functionality when you can check by pinging the exact IP address of your eth0 or NIC1? pinging loopback address is nothing to with cheking your network card, you should ping your network card's ip address to check if its working or not.

 

[Morsing]

Pinging any local ip address, even the NIC's, won't tell you a thing. IP packets are returned by the IP layer before it hits the NIC.

Only problem would be if the NIC was so damaged that you can't bring up the interface but unplugging the cable definately won' prevent pinging the NIC.
If the NIC breaks while it's operational I doubt that the interface will be deconfigured in the kernel.

So, was this problem ever solved?

Cheers


Henrik Morsing
Certified AIX 4.3 Systems Administration
& p690 Technical Support

 

[eanda10]

so far so good all I did was replace the patch cable and plugged it into a different port on the switch I have not noticed the error in my log over the last two days lets hope for the best!!!!!!!

 

[bluegroper]

Looks like 'twas prolly a dud patch cable.