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strange network problem (please help!)

strange network problem (please help!)

Post by Reiner Gries » Tue, 11 Feb 2003 03:13:10



Hi there,

I *really* don't have any clue what the cause for this (simple?!)
problem is...
I'm using OBSD 3.0 as a router (pf/nat) with two 10 MBit
ethernet cards (ne3 and ne4). Yesterday I installed a new 100 MBit
network card (sis0). The new card got the IP of the old ne3
(192.168.10.2) and the old card got a new IP (192.168.10.5). I can
ping 192.168.10.2 and 192.168.10.5 from another machine. I can delete
(!) the old card with 'ifconfig ne3 delete' and everything keeps
working. Fine.

The problem: if I remove the old card physically, I'm no longer be able
to ping the new card! It seems obvious, that the ping packets are going
through the old card (ne3, which now not even have an IP!) to the new
(sis0).

How can that be? Oh, man... I need some help...

reiner

======================
Here are some facts...

$ ifconfig -a # here ne3 is not yet deleted
ne3: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        media: Ethernet autoselect (10baseT)
        inet 192.168.10.5 netmask 0xffffff00 broadcast 192.168.10.255
        inet6 fe80::200:b4ff:fe52:ea83%ne3 prefixlen 64 scopeid 0x1
ne4: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        media: Ethernet autoselect (10baseT)
        inet 10.0.0.0 netmask 0xff000000 broadcast 10.255.255.255
        inet6 fe80::200:b4ff:fe52:e937%ne4 prefixlen 64 scopeid 0x2
sis0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        media: Ethernet 100baseTX
        status: active
        inet 192.168.10.2 netmask 0xffffff00 broadcast 192.168.10.255
        inet6 fe80::240:f4ff:fe3b:6a0d%sis0 prefixlen 64 scopeid 0x3
[...]

$ cat /etc/hostname.ne3
inet 192.168.10.5 255.255.255.0 NONE
$ cat /etc/hostname.sis0
inet 192.168.10.2 255.255.255.0 NONE media 100baseTX

$ route -n show
Routing tables

Internet:
Destination      Gateway            Flags
default          212.185.255.165    UG    
10.0.0.0         link#2             U      
127.0.0.0        127.0.0.1          UG    
127.0.0.1        127.0.0.1          UH    
192.168.10.0     link#1             U      
192.168.10.1     0:40:f4:34:76:3c   UH    
192.168.10.2     127.0.0.1          UGH    
212.185.255.165  62.155.188.96      UH    
224.0.0.0        127.0.0.1          U      

$ netstat -rn
Routing tables

Internet:
Destination        Gateway            Flags     Refs     Use    Mtu  Interface
default            212.185.255.165    UGS         3      424   1492   tun0
10/8               link#2             UC          0        0   1500   ne4
127/8              127.0.0.1          UGRS        0        0  33224   lo0
127.0.0.1          127.0.0.1          UH          4      124  33224   lo0
192.168.10/24      link#1             UC          0        0   1500   ne3
192.168.10.1       0:40:f4:34:76:3c   UHL         2      833   1500   ne3
192.168.10.2       127.0.0.1          UGHS        1      267  33224   lo0
212.185.255.165    62.155.188.96      UH          1        0   1492   tun0
224/4              127.0.0.1          URS         0        0  33224   lo0

 
 
 
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strange network problem (please help!)

Post by Reiner Gries » Tue, 11 Feb 2003 04:39:46



> Hi there,

> I *really* don't have any clue what the cause for this (simple?!)
> problem is...

simple, indeed. And... solved.

 
 
 
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strange network problem (please help!)

Post by Peter Str?mber » Tue, 11 Feb 2003 04:47:16




Quote:> Hi there,

> I *really* don't have any clue what the cause for this (simple?!)
> problem is...
> I'm using OBSD 3.0 as a router (pf/nat) with two 10 MBit
> ethernet cards (ne3 and ne4). Yesterday I installed a new 100 MBit
> network card (sis0). The new card got the IP of the old ne3
> (192.168.10.2) and the old card got a new IP (192.168.10.5). I can
> ping 192.168.10.2 and 192.168.10.5 from another machine. I can delete
> (!) the old card with 'ifconfig ne3 delete' and everything keeps
> working. Fine.

> The problem: if I remove the old card physically, I'm no longer be
> able to ping the new card! It seems obvious, that the ping packets are
> going through the old card (ne3, which now not even have an IP!) to
> the new (sis0).

> How can that be? Oh, man... I need some help...

Are aware that when you remove the ne3 card the ne4 card is "renamed" to
ne3 (and uses hostname.ne3 instead of hostname.ne4) ?

--
Peter Str?mberg
ISCCIV02  <http://www.iscc.nu/>

 
 
 
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strange network problem (please help!)

Post by Reiner Gries » Tue, 11 Feb 2003 07:24:44





>> [...]
>> The problem: if I remove the old card physically, I'm no longer be able
>> to ping the new card! It seems obvious, that the ping packets are going
>> through the old card (ne3, which now not even have an IP!) to the new
>> (sis0).

>> How can that be? Oh, man... I need some help...

> Are aware that when you remove the ne3 card the ne4 card is "renamed" to
> ne3 (and uses hostname.ne3 instead of hostname.ne4) ?

Yes, this was also an issue. But the main problem was a routing problem:
packets were sent out through the old ne3 but came in on ne4.

thanks you!
reiner

 
 
 
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1. Strange network problem, PLEASE HELP!

I am having a strange network problem on our server testing network!

We run CIFS sessions from each client to each server under load for at
least
16 hours at a time. We may have 150 servers being tested at any given
time.

We have a simple network of switches in a hub/spoke configuration, no
redundant links or circular paths. We have 1 "core" switch, an extreme
summit 5i, and 4 other summit 5i's connected to the 'core' switch. They
all
have the latest firmware and default settings to make them 'dumb'
switches.
Connected to each of the summits are about 6 links, each going to a
separate
rack of servers. Each rack has a dumb switch (netgear / etc..) which
all the
servers connect to.

Here's the problem: At random times, about 4-10 times a day, we get
flooded
by single network sessions. Every one of the extreme 5i ports will be
solid
orange with collisions. I have one sole machine plugged into an
ordinary
port on the 'core' 5i (no port monitoring, just an ordinary port). I
run
Ethereal on this machine, and it always shows one direction of the
SAMBA
conversation between a test client and server. The MAC address is
UNICAST,
and the IP is UNICAST.

I will kill the test in question, and the summit's will immediately
clear
up.

So WHY do I get this packet on an ordinary switch port, when I am the
only
machine on this port???? This happens in a seemingly random manner,
between
various clients, and various servers, not isolated to one rack or one
summit
5i. We have taken all the 5i's out of the path except 1, and the
problem
occurred. Then we swapped out that summit 5i with another one, and the
problem reoccurred.

The servers under test have multiple ethernet adaptors, but each
adaptor is
on a different class C subnet. The test clients have 1 or 2 ethernet
adaptors, with one ip alias per machine corresponding to each class C
subnet, shared with the server under test.

Has anyone seen this before? Or have some idea as to why this problem
is
occuring? The core switches are all high-end switches, and shouldn't be
filling up their MAC tables. They're all Gigabit as well, so bandwidth
shouldn't be a problem. And if it was, why only a single session being
broadcast?
???

Thanks a MILLION in advance,

-AnthonyM

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