HELP! iMac, cable modem won't go.

[stripes]

Hello ChrisT, and thanks for those ideas.

(In fact the elderly machine is a 1997 G3 but doesn't affect your conclusions).

I tried powering down for twenty (yes 20) hours, yesterday afternoon to today, with no change, so that probably rules out the power-down as a solution.

Various threads on the Apple Store discussion forums show quite a few other iMac/cable modem problems, with the super-fast Intel iMac being allegedly too advanced for the old bog-standard modems. But on the other hand there are thousands of iMac users out there connected happily to the www, so I don't think it's inherent in the iMac.

Solutions in the States have been varied, including buying new cable modems (not an option here in the UK), slowing down the ethernet speed on the Imac, etc. The router solution hasn't been suggested, or rather I can't find it, but there are hundreds of messages, so a bit difficult.

How about this router idea? Is there any logic to it, i.e. does the ntl signal come rattling down the line, into the modem, find its way blocked by a router, and give up rejecting my iMac? Or is this just fanciful.

I'm fairly laid back about the problem, now, as a) I am old, and therefore have a degree of patience, b) it WILL be solved, sometime, and c) not being connected to the Internet isn't the same as having your leg sawn off (believe me, I know about that one).

However, the flat is tiny, and I really would like to give away the G3 (if I can find any takers) and concentrate on playing with my shiney iMac.


Thanks again, and further ideas still DESPERATELY welcomed.


Allen.

[maverick]

The cable modem your using is it an Ambit model you can tell if it has got rdy and sync lights.
If it is then unscrew the coaxial cable from it,reboot the mac and re check the ip address,let us know what ip appears,reconnect the coaxial cable reboot modem and the mac and again recheck the ip.

[melevittfl]

OK,

On the cable modem, there should be a light labeled "Enet". When you plug the ethernet cable into the iMac, that light should light up.

If it doesn't then your iMac and your cable modem aren't making a physical connection. Before buying a router, try a new ethernet cable.

If the light does come on, that your iMac is making a physical connection, then, can you please open the Applications folder, then open the Utilities folder and run the Terminal application. You'll see a black screen with a command-line prompt. Type "ifconfig" (without the quotes) and press enter. If you could, please copy and paste the output so we can see it.

Thanks,
Mark

[bayonet]

As maverick says when you disconnect the coax the IP should be 192.168.100.x didn't I see you had that somewhere earlier but if it connects to the old MAC it should connect ok to the new one

I don't get a lot of calls with MACs just plug 'em in and away to go

Set Network to Automatic built in enet and assigned by DHCP they usually pick up an IP address no problem no fuss

I'm sure the MAC bods on here will advise even better than someone who has a limited knowledge of them like me. They don't give much problem on routers either

[ShadowTD]

This is tres odd.

Thanks to other posters for clearing up the MAC address points. I would maybe suggest that at this point you try to get a new cable modem out of Ntl, as yours really seems to have a problem. The new Intel Macs use standard Intel chipsets these days, so it's not just a 'Mac thing'.

However, if there are documented Cable Modem/Mac Ethernet problems you could always buy a router from Argos and take it back if it doesn't solve the problem - god bless that 14 day Money Back Guarentee!

[melevittfl]

Again, the first thing to check is that the Enet light on the cable modem is on.

[Stuart]

Originally Posted by ShadowTD

This is tres odd.

Thanks to other posters for clearing up the MAC address points. I would maybe suggest that at this point you try to get a new cable modem out of Ntl, as yours really seems to have a problem. The new Intel Macs use standard Intel chipsets these days, so it's not just a 'Mac thing'.

However, if there are documented Cable Modem/Mac Ethernet problems you could always buy a router from Argos and take it back if it doesn't solve the problem - god bless that 14 day Money Back Guarentee!

It's worth noting that the Macs have always followed international standards for Ethernet. As should all devices attached via Ethernet (NTL modem included).

One thing that can cause a problem though. When you connect a device to Ethernet, there are several speeds it can operate at. Therefore, each device has to try different speeds to see which the other can use. This is called "Auto Negotation".

Now, not sure if you can do this on the mac (sadly, I'm at home, and don't have access to a Mac to try) but it might be possible to force your mac to use either 10 or 100 Mbit.

[stripes]

Right, thanks for all those.

I'm connected through the G3 at the moment.

Modem is an 'ntl 250'. Sync and Ready come on. Enet comes on. Disconnecting coaxial changes nothing. IP address under all test conditions comes back as 169...

Just looking at ifconfig. Yes, got to that stage, Mark, but I haven't got any physical connection between the two machines, so can't copy and paste. I know it's very difficult doing this from a distance, but can you tell me what I'm looking for (or rather what YOU'RE looking for)?

Stuart: I have changed the speed (tip from the Apple Discussion message board) but still 169...
You can choose speeds of 10, 100, or 1000.
You can choose half-duplex, full-duplex, or full-duplex flow-control.
You can choose Maximum Packet Size either 1500, or 9000, or custom, range 72-9000.
I tried the low figures in all cases, with half-duplex, then full-duplex. All came back to 169 (and yes, I did reboot iMac and modem each time).

Shadow: I asked NTL for a new modem. I even offered (this is how desperate I am) to PAY for a new modem from them. Point-blank refusal. 'If the modem is working on the G3, then there's nothing wrong with it.' They did send an engineer out early on in the saga, who didn't know much, but who stuck a meter on the modem and said the signal was okay. That was as much as he knew about modems.

I spotted the Apple-recommended router (Belkin 4-way) on Amazon's 'used' list, and as it was only twenty-five quid have ordered it. At least it'll eliminate that area.

So, thanks again for your help, and at the moment I'm pinning my hopes on that router, on the basis that the signal will recognise the modem, then hopefully the router, then my G3, and won't trouble it's pretty head about what else I've got hanging off the router. (But does this mean that I've got to keep the G3 for ever and ever? I wonder).


Allen, sinking.

[Dark Fiber]

We're still not clear- when you attach to the new Mac, can you see the modem web page at 192.168.100.1?
There's a problem with the modem, the Mac or the cable/plugs/sockets. Getting a router will only complicate matters further!

[stripes]

Hello Dark.

Don't know what a modem web page is. (Just tried that address on this working Mac, the old G3, and got an NTL page with details of the modem, MAC address, etc. I'll do it again (for the nth time) on the new iMac in a minute, but I'll have to shut down to rewire the system. Reporting back later).

Mind you: I've NEVER seen an IP address EXCEPT starting with 169 when connecting to the new iMac.

To repeat, all tests, all different combinations of cable, speeds, etc., ALL come up with 169 IP address.

Allen.

[melevittfl]

Originally Posted by stripes

Right, thanks for all those.

I'm connected through the G3 at the moment.

Modem is an 'ntl 250'. Sync and Ready come on. Enet comes on. Disconnecting coaxial changes nothing. IP address under all test conditions comes back as 169...

Just looking at ifconfig. Yes, got to that stage, Mark, but I haven't got any physical connection between the two machines, so can't copy and paste. I know it's very difficult doing this from a distance, but can you tell me what I'm looking for (or rather what YOU'RE looking for)?

Hi, sure no problem.

ifconfig prints out the status of all of the available network interfaces. You're looking for the section that starts with "en0:". That's the ethernet jack.

What I'm interested in is the line that starts with "media:" including the "status:" field.

An example of what is should look like is below:

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULT ICAST> mtu 1500
inet 192.168.0.50 netmask 0xffffff00 broadcast 192.168.0.255
ether 00:0d:93:31:08:e8
media: autoselect (1000baseT <full-duplex>) status: active
supported media: none autoselect 10baseT/UTP <half-duplex> 10baseT/UTP <full-duplex> 10baseT/UTP <full-duplex,hw-loopback> 100baseTX <half-duplex> 100baseTX <full-duplex> 100baseTX <full-duplex,hw-loopback> 1000baseT <full-duplex> 1000baseT <full-duplex,hw-loopback> 1000baseT <full-duplex,flow-control> 1000baseT <full-duplex,flow-control,hw-loopback>

[stripes]

Right, Dark...

Sorry, thought that was an IP address initially, but now I see what it does.

Okay.

On my original, working machine, the G3, I get:

Cable Modem Information Cable Modem : Euro-DOCSIS 1.0/1.1/2.0 Compliant MAC Address : 00:0e:9b:fd:0d:3e Serial Number : 000E9BFD0D3E Boot Code Version : 2.1.6d Software Version : 2.94.1010 Hardware Version : 1.19

On my new, non-working machine, the iMac, I get PRECISELY the same information, every figure just the same.

I don't know whether this is a good or bad thing! (Don't be fooled - sometimes I might sound as if I know what I'm doing, but I don't.)

Mark:

the line you refer to reads:

media: autoselect (100baseTX <full duplex, flow control> status: active

Does that help at all?


I've copied all the ifconfig data onto a word processing doc on the iMac, so can read it off and retype any other bits you may need.




Thanks again for trying.


Allen.

[NTLVictim]

If Stripe can see the modem page on both Macs but can only see the Internet on the G3, logically that points at the Imac being refused throughput for some reason...second opinion, please!

[melevittfl]

Originally Posted by stripes

media: autoselect (100baseTX <full duplex, flow control> status: active

Does that help at all?

Hi,

OK, well it seems that both the cable modem and the mac are seeing that there is, in fact, a cable plugged in.

That means it's probably not a bad cable.

The fact that you can browse, on the iMac to the 192.168.100.1 address means that the low-level connection is working. I.e., the Mac is able to communicate with the cable modem.

So, we've eliminated a physical connection problem and we know the basic TCP/IP stack is working.

So, it's definitly a problem with the process whereby the mac requests an IP address from NTL and one is assigned.

We don't yet know which end has the problem. I suspect it's a strange iteraction between the two.

One thing, you mentioned you have a new Mac. Can you click on the Apple icon in the top left of the screen and click "About this Mac".

There should be something that should exactly the version of OS X it's running. I.e. 10.4.SomeNumber.

[NTLVictim]

I said that, but I was more concise.

---------- Post added at 13:40 ---------- Previous post was at 13:32 ----------

Is this germane to the problem?

http://macosx.com/tech-support/probl...hcp/12602.html