Re: [tlug] network losing connection

[Matt Gross <mgrossjp@??>]

On Tue, 2007-02-27 at 10:54 +0100, Sigurd Urdahl wrote: 
> Matt Gross wrote:
> > Hi Everyone,
> >
> > I am having a lot of problems with my Fedora Core 6 server connection
> > going down when traffic increases.  I bought a new switch (mine is quite
> > old) in hopes of fixing the problem, however, that seems to have
> > exacerbated the problem.  
> >   
> It could be both an ethernet problem and a problem higher up. The 
> suggestion to read logs is a good starting point.
> 
> If it's an ethernet problem you should be able to see it in the output 
> from ifconfig:
> 
> sigurdur@??:~$ /sbin/ifconfig
> eth0      Link encap:Ethernet  HWaddr 00:13:D3:C1:CF:A0 
>           inet addr:192.168.43.135  Bcast:192.168.43.255  Mask:255.255.255.0
>           inet6 addr: fe80::213:d3ff:fec1:cfa0/64 Scope:Link
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:9184658 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:8403557 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:1000
>           RX bytes:1260796022 (1.1 GiB)  TX bytes:2957724591 (2.7 GiB)
>           Interrupt:217 Base address:0x4000

here is mine:

[root@?? ~]# ifconfig
eth1    Link encap:Ethernet  HWaddr 00:16:17:B7:D9:03  
        inet addr:192.168.0.246  Bcast:192.168.0.255 Mask:255.255.255.0
        inet6 addr: fe80::216:17ff:feb7:d903/64 Scope:Link
        UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
        RX packets:8165 errors:0 dropped:0 overruns:0 frame:0
        TX packets:6885 errors:0 dropped:0 overruns:0 carrier:0
        collisions:0 txqueuelen:1000 
        RX bytes:8445125 (8.0 MiB)  TX bytes:656304 (640.9 KiB)
        Interrupt:21 Base address:0x8000 

I know that it does not show a lot of packets, but before I rebooted my
server it also said errors:0

> 
> If "errors" increases it's at least an indication that this problem is 
> ethernet related.
> 

I swapped the ethernet cables for new ones between my server, the hub
and the hub and the firewall box.  Still having a problem.

> Is the problem noticeable between computers on the same LAN, or only 
> through a broad band router or something like that? If the former, try 
> setting static arp entries on both servers to see if it's an arp related 
> problem.

I don't think it is a problem with the arp cache.  After the problem
happened, the arp cache is still showing a correct entry:

[root@?? ~]# arp -a
? (192.168.0.254) at 00:90:CC:42:71:58 [ether] on eth1

Does the question mark above signify anything important? 

I did notice that when I am having the problem, the following takes
several seconds to complete:

[root@?? ~]# arp -va
? (192.168.0.254) at <incomplete> on eth1
Entries: 1      Skipped: 0      Found: 1

I noticed the <incomplete> and tried to add the arp entry manually, but
that did not fix my problem.

> 
> kind regards,
> -sig
> 
> -- 
> Sigurd Urdahl
> Linux, goofing, cooking, making fire, computer security, having a
> beer. Give me good music.
> 
>

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