Cable Forum - Mac address

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Quote:

Originally Posted by printerman

my ip address is shown as a group of numbers(no just zeros and not starting with 169), a submask is shown, and the physical address is shown as 00:00:00:00:00:00.

An IP address beginning 169.x.x.x is not a 'valid' IP address. It is used when there is a network cable but no response from a DHCP server. Also the MAC address should not be reported as 00:00... The lack of IP address is consistent with not having a valid MAC address. With a 169 IP address I wouldn't expect you to get any connectivity to the internet!

Are there any newer drivers/BIOS for your Mobo? Can you buy a cheap NIC from PCWorld/Maplins to try?

I have a 'valid' ip address...it DOES NOT start with 169...but my mac address is 00:00 etc..... can any one help me?

Give us the first part of your IP - i.e. 192.168.x.x - but your MAC should NOT be 00:00:00:00:00:00 - please answer the questions above - have you installed your latest drivers for your MOBO?

Also, have you had a look in your BIOS for network card settings if it is onboard?

What type of MOBO is it? Nforce etc...

Is it a normal ethernet interface that you are using that shows MAC as all 0's or are you USB to a cable modem?

Please be as specific as possible.

yes, sorry i'm not helping by not answering questions. I'm at work so i can't check everything right now but info so far.

Asrock K7S8X board. I actually have a connection but it drops off.
I've just installed xp and not tried the drivers from there website yet although i do have drivers installed from the disk provided by asrock.
Its an onboard ethernet SiS900 adapter connected directly to my ambit modem. It's Not USB.
I haven't looked at my bios yet..what should i be looking for?

Just checked the manual for your MOBO here, http://www.asrock.com/Drivers/Manual...S8X_UM_v10.pdf, and it dosent give you an option to change or set the MAC address so its not a BIOS issue.

I dont know why you have this problem, it shouldnt be that your MAC address is all zeos and im frankly amazed that you have a connection to the internet at all. I doubt drivers will fix it as you have never had to set the driver before, sooo i can only assume you have a faulty NIC.

Sorry

Oh! I'm not very happy about that. the board is just out of warranty.....is it possible that a connection inside could be a problem, some sort of short or a jumper dropped off or soemthing...i'll have to have a look tonight.

A short is a possibility - also if there is a lot of dust - give it a good vac as well as that can lead to shorts too.

I still dont understand how you get a connection at all though? Does the network light go out on the back of your case when the connection dies?

Quote:

Originally Posted by threadbare

unfortunately winipcfg is not available on xp. shame really as its quite handy

But it is available on win98 which the OP says he is using :)

A MAC address is supposed to be a unique HARDWARE based serial number of your network card. It consists of 12 digits usually seperated by dots. eg: A0.12.23.34.45.56. You cannot change the physical address of this card, it is possible however, to spoof (Disguise) the MAC address, but this is another story.

It would seem however that MAC address is a red herring as has been stated. XP appears unable to detect the MAC address. If you are getting a DHCP server assisgned "Valid" IP address then the mechanism is working (Simply that XP is unwilling to show it).

The negotiation process for an IP is pretty straight forward In basic terms, Your PC is setup for DHCP client, when you power on it sends a broadcast out on to the network and a DHCP server should respond, it then assigns you an IP address that is then linked (Virtually) to your MAC address. hey presto you have an IP address. You are leased the IP address only, after a certain time the IP address can be renegotiated for or the DHCP server releases it to be used by somebody else.

If your connection is dropping and you keep the same IP address when it restarts, then I suspect that it is not the DHCP negotiation process but something external, cables, cable service, something overheating, PC, software etc.

If you are losing the IP address then it may be that your service is physically stopping OR your lease has run out and is unable to renegotiate with the DHCP server to keep the existing address.

Quote:

Originally Posted by threadbare

unfortunately winipcfg is not available on xp. shame really as its quite handy

You can download the NT version of it, you can use this on XP.

http://www.microsoft.com/windows2000...wntipcfg-o.asp

Quote:

Originally Posted by Tay

Good explanation. Just to expand - in the case of the NTL setup, NTL provide the DHCP server, and addresses are leased for quite a time (don't quote me, but two weeks rings a bell). After a percentage (I think it is 50%) of this time, if you are connected, or the next time you connect, the lease is renewed for a further period (two weeks?). It is because of this mechanism that your NTL-assigned IP address, although theoretically dynamic, rarely changes. In this case, the mystery is a) why does the PC NIC MAC address show up as zeros? and b) how does ANY connection occur? Can DHCP allocate an IP address to an all-zeroes MAC address, and, if so, could this be causing a problem, e.g if there are other all-zero MAC addresses on the NTL network?

As noted earlier, it is possible to 'spoof' the MAC address on some, if not all, cards (e.g. - on Windows 2000 at least - Network Connections, right-click on connection, select card properties, advanced, 'locally-administered address'). Could it be that a virus or some such has changed this 'software' address?

I find it hard to believe it to be a virus, but i don't disagree 100% with you. It is screwing up my machine a bit. Its a fresh install on a formated drive. I used a nuke program to completely wipe th HDD, i had to partition it and format it before use. I don't think a virus can survive that (can it?). I'm going to have a look in the bios, and also 'control panel, network connections, status and properties' to see if the address is showing up there. If it is i would guess its a software problem. If its not showing there (which i bet it isn't!) i guess its a hardware fault. I've got a seperate PCI 10/100 card i can plug in and install. I'll see if thats any better.

Quote:

Originally Posted by printerman

I've got a seperate PCI 10/100 card i can plug in and install. I'll see if thats any better.

That would be the quickest & easiest option. :)

Quote:

Originally Posted by JohnHorb

Just to expand - in the case of the NTL setup, NTL provide the DHCP server, and addresses are leased for quite a time (don't quote me, but two weeks rings a bell).

Lease times for full service IP addresses are 48 hours. :)

Quote:

Can DHCP allocate an IP address to an all-zeroes MAC address, and, if so, could this be causing a problem, e.g if there are other all-zero MAC addresses on the NTL network?

This is theoretically possible, yes. If two devices on the same DHCP server have the same MAC address (in this case 00:00:00:00:00:00), things could be getting confused.

Quote:

Originally Posted by jimbo

Lease times for full service IP addresses are 48 hours. :)
.

My mistake - I thought it was longer, but it's a long time since I was able to check - I'm now behind a router which doesn't show the lease times.