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Old 02-05-2006, 01:18 PM   #1
saranjothy
LQ Newbie
 
Registered: Feb 2006
Posts: 15

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Unhappy unable to get mac address - TX error in dmesg


Hi ,
I have a Hitachi Solution engine board for which i m trying to get the Networking.

I have built the Root file system from scratch having all the necessary entries for Networking.
( i installed all redhat packages for building the
Root file system)

But still the Network is not up.( this i have verified by pinging from other systems, Even arping is not working)

I have checked for the important networking scripts such as

\etc\sysconfig\network-scripts\ifcfg-eth0
\etc\sysconfig\network-scripts\ifcfg-eth1

\etc\sysconfig\networking\devices\ifcfg-eth0
\etc\sysconfig\networking\devices\ifcfg-eth1
All are fine.basically there are two interfaces in my board


Some Details:

1 . when I type ifconfig i m able to get all the information required such as
IP address and others.

Except the Mac address
The mac address looks something like this.
00:00:00:00:ff:ff

Is it correct to have like this??

2. when i type arp i got the output like this

$ /sbin/arp

hardware address
incomplete


3. When i tried to do arping it gets failed.


4. i checked the dmesg.

it shows something like TX error: dirty_bit bla bla.......


I feel the problem is with finding the Mac address...Please share with me you views and suggestions.

BTW, im a newbie to Linux Networking .

Thanks in advance.

regards
SaranJothy.
 
Old 02-05-2006, 01:45 PM   #2
Half_Elf
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Registered: Sep 2001
Location: Montreal, Canada
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Just a suggestion, but do you know you can "spoof" MAC adress in linux? It is network admin nightmare nor something very ethical, but it is quite useful sometime . I'm not sure what your problem is/is caused by but if the driver is just having bad time loading the MAC, you could assign one by yourself.
1- Make sure your network card is down:
ifconfig eth0 down
2- Assign the new MAC you want to use :
ifconfig eth0 hw ether DE:AD: DE:AD:BE:EF
3- Up your card or call back the DHCP.

Most MAC address are legal, but avoid those with "FF" or "00" that might mean something (as example FF:FF:FF:FF:FF:FF is the loopback and should NEVER be used).

I hope this help.
<edit>Annoying smiley</edit>

Last edited by Half_Elf; 02-05-2006 at 01:46 PM.
 
Old 02-05-2006, 04:25 PM   #3
saranjothy
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Registered: Feb 2006
Posts: 15

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Thanks for reply.
I will try this.


I have some more queries.

1. Do we really need to know mac address of a PC to ping it?

2. When i tried to ping the Board(which has the mac address problem) it is possible via a Hub (Inspite of the problems stated above) but not via a Router.
I mean networking is up But only via a HUB not via a Router.
What can be the problem.?

Bcoz the mac addresss is looking like 00:00:00:00:ff:ff and unable to do ARPING
can i come to the conclusion that the problem is only with MAC address.
Can it be due to any other problem?



Sorry if my questions are too childish :-)
please help.


Regards
Saranjothy
 
Old 02-05-2006, 05:35 PM   #4
Half_Elf
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1. Do we really need to know mac address of a PC to ping it?
You do. MAC address is the lower (or last) level (or step) of networking. Ip address are used to find out if you are on the same network as your target, so the OS can determine if it has to send to an intermediate router or if it can send directly to the target. If the OS know it is on the same network, it does an ARP request to find out "who" the client is, otherwise it does an ARP request to find out "who" is the router. Network card can't communicate with anything but MAC address. Ip and hostname address are handled by the OS, but ultimatly, the network card need the physical address (MAC address) of the target to talk.

2. When i tried to ping the Board(which has the mac address problem) it is possible via a Hub (Inspite of the problems stated above) but not via a Router.
Now this is strange... It may be caused by various cause.
First of all, the difference between a hub and a router is that the Hub is only a "check point" that concentrate the electric signal on a network. It doesn't try to find out where the packet (I assume you know what a packet is ) is going. In fact, any packet send to a hub is sent back to each and every port; it's exactly like your cable was suddently divised into several cables. A hub is a dumb device. No CPU, no OS, it's just pure circuitry.

On the other hand, router does try to find out where a packet should go. Router are "routing" the packet to it's destination. If you send a packet to a router, the OS in the router will find out to which port it should go and send it back _only_ to this port. On course, as I said in "1-", it need the MAC address to do so. Modern router also include some feature like DHCP server and firewalling. So a router is in fact an "intelligent" device.

Bcoz the mac addresss is looking like 00:00:00:00:ff:ff and unable to do ARPING
can i come to the conclusion that the problem is only with MAC address.
Can it be due to any other problem?

Well, hard to say. It's very unclear why you can't ping throught the router but that you can throught the hub. My guess about it would be that your router is doing some filtering on MAC to prevent "illegal" MAC address on your inner network (and obliviously 00:00:00:00:ff:ff is giving him some problem). Or maybe the 00:00:00:00:ff:ff is just forbidden by <something> (standard, rfc, micro$oft or whatever) your router is respecting but not Linux ? Or maybe your Linux computer doesn't answer correctly to the ARP request (maybe it answer the real MAC address instead of the buggy one??). It's really hard to say and it would need some time to figure this out. If you want to try, you could use program like "tcpdump", "ethereal" or "iptraf" to listen to networking packet. Or (easier) just change your MAC and check if it works

In any case, you can't say that ARPING is failing because your MAC is wrong, but you can't say otherwise either. I agree it is quite suspect but it could be something else (buggy router? broken driver? interstellar aliens sending telepatic crap on your network?), who know.
For now try the fix I gave you earlier, if it fails, maybe a search on google could give you some hints...
 
Old 02-07-2006, 08:20 AM   #5
saranjothy
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Registered: Feb 2006
Posts: 15

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Dear HalfElf,
Thanks for your Detailed reply.

We fixed the problem something like this.
Now, As i already told i m unable to ping the router.But its possible ping a system via a HUB.

As told by HalfELF there is something cryptic going on at Router which is making the things difficult.


But our Main isssue of communicating with Router is solved like this.
We connected the Board to the Hub and then from Hub to the Router.
Now its possisble to ping the Router.
Router is from Linksys.

Although my problem is solved, if anybody get some idea this one please share with me at saranjothy at gmail dot com .

Thanks for your support guys.


Regards,
SaranJothy.
 
Old 02-07-2006, 12:49 PM   #6
Darin
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Registered: Jan 2003
Location: Portland, OR USA
Distribution: Slackware, SLAX, Gentoo, RH/Fedora
Posts: 1,024

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Quote:
Originally Posted by saranjothy
...We connected the Board to the Hub and then from Hub to the Router.
Now its possisble to ping the Router.
Router is from Linksys.

Although my problem is solved, if anybody get some idea this one...
Crossover cable vs straight-through cable?
 
  


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