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Old 12-01-2002, 11:17 AM   #1
browny_amiga
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Registered: Dec 2001
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Distribution: Kubuntu 10.04, Debian Squeeze, Windoze 7
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Unhappy 2 NIC problem, no internal ping, only external


Hi

I have this tough cookie here which is in the process to drive me crazy:

Out of the box Redhat 6.2 running on 100MHZ Pentium, 2 NICs installed,
PCNET32 (10.10.10.11) + RTLxxxx (10.10.10.10) (Realtek something).
This setup is a trial for an internal net / internet setup.

The Problem: When on the box, I cannot ping any of these two cards, which first indicated to me that they don't work properly. Funny thing is that from external boxes I can ping all right on both IPs and ifconfig shows them (eth0 eth1 lo) properly up.
The module config should be alright since I wrestled with this a lot and also read several FAQs for the 2 NIC scenario.
The funny thing is that although I cannot ping localy, I use a client/server application that can connect to 10.10.10.10 no problems, data exchange works both ways (looks like there is a bi directional problem?)
No firewall is on currently, so nothing is blocked.

I am a little lost here, since I know that ping is one of the basic things that need to work, so I am amazed that I can use that NIC for datatransfer but not ping it localy.

Is there some kind of diagnosis that I can run to find out what is foul? Could the motherboard (pci) be damaged? Before, when I only had 1 NIC, it worked perfect!


Any pointers appreciated
(from a not-so-much newbie-anymore that is stuck ;-)

Markus
 
Old 12-01-2002, 11:24 AM   #2
clavius
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Location: Romania, Tg-Jiu City
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Re: 2 NIC problem, no internal ping, only external

Quote:
Originally posted by browny_amiga
[B]Hi

Out of the box Redhat 6.2 running on 100MHZ Pentium, 2 NICs installed,
PCNET32 (10.10.10.11) + RTLxxxx (10.10.10.10) (Realtek something).
This setup is a trial for an internal net / internet setup.

The Problem: When on the box, I cannot ping any of these two cards, which first indicated to me that they don't work properly.
Your problem is that you have IPs from the SAME subnet on 2 different NICS. So your cards are Ok, but change one's IP to another one, on other subnet.

Seach with google about networking tutorials on routing and you'll see why
 
Old 12-01-2002, 06:39 PM   #3
browny_amiga
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Original Poster
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Cool

Thanks for the pointer. Although I know quite some things about TCP/IP, that routing stuff and subnets was always (is still ;-) somethign that evades me.

I will look into it. Do you know any URL where they specifically talk about WHY it does not work?
I was always thinking that the 2 NICs would communicate perfectly, since they are almost ...connected... to eachother..

Anyway, thanks for the help. Routing is my next study subject !

Thanks again

Markus
 
Old 12-02-2002, 01:21 AM   #4
clavius
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Quote:
Originally posted by browny_amiga
I will look into it. Do you know any URL where they specifically talk about WHY it does not work?
I was always thinking that the 2 NICs would communicate perfectly, since they are almost ...connected... to eachother..
They communicate PERFECTLY, but think about it:
You type "route -n" and....
You have TWO routes:
10.10.10.0 255.255.255.0 eth0
10.10.10.0 255.255.255.0 eth1

If you generate a packet, WHERE did the router (Linux, Cisco, Windows NTs) know WHERE to send it ? On eth0 OR eth1 ?
 
  


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