DHCP problem

[jimothy]

I've got a strange DHCP problem.

My network setup is

WAP
|
|
Hub
|
|
Router
|
|
Cable
Modem


My Router is running a DHCP server, and everything access it hunk dory getting IP addresses in the range 192.168.2.1 to 192.168.2.100 with a subnet of 255.255.255.0.
Apart from my Powerbook. If I connect to the network using the Airport Wireless card, via the WAP, it gets an IP address from the Routers DHCP server.
If I plug a network cable from the powerbook to the hub directly, rather than via the WAP, it gives me a strange IP address. it comes out as 164.something.or.other, with a subnet of 255.255.0.0 (which I believe is the default for no DHCP found).

Any idea why it can't seem to find the DHCP server? Or if it's finding another one, how can I search my network for DHCP servers?

Thanks

[scorp]

DHCP is an extension of the ARP protocol if memory serves, use a packet sniffer like 'ethereal' to dump whats going on, you can see the DHCP exchanges clearly if you have nothing else going off on the network.

[pdV6]

Don't know much about Apples, but you're using 2 different network connections on the Powerbook: the wireless one and the wired one. Are the settings for the wired one (i.e. "obtain IP via DHCP yes/no" or similar) set the same on both connections?

[Plotloss]

Isnt there two sorts of DHCP discovery as well?

I have a Bluetooth LAN Access point and I cant get that to handshake with anything and its apparently to do with the way that DHCP assigns leases whether it be on a broadcast or request basis.

[UpTheIron]

jimothy said:

164.something.or.other, with a subnet of 255.255.0.0

Do you mean 169.254.x.x/16 - i.e. an APIPA address? Assuming you do, the first thing I would check in your scenario is the patch cable you are using to connect the Mac to the hub.

- APIPA suggests that the MAC is trying to obtain a DHCP address
- Other devices working (you don't confirm this includes wired devices connected to the hub)
- Mac working on the wireless connection

All suggest that the Mac, the DHCP server and the hub are working...

[_dobbo_]

First thing I'd try would be to manually set the IP/subnet/gateway, then ping the router.

If that fails, you know that there's an underlying hardware issue, not an issue with DHCP. No sense trying to diagnose an issue till you confirm that it actually is the issue which requires attention.

Having come across this sort of problem more than once, I've hardcoded my desktop at home leaving the laptop to get it's IP via DHCP.

[jamieboy]

Not sure what version of Mac OS you're using, but I had a problem where an blue'n'white G3 with OS 9 (I think, can't exactly remember, but definitely pre OS X) wouldn't get a DHCP address from a Netgear DG834. The only solution I found was to statically assign an address, although I can't explain why yours should work wireless but not wired.

Numpty question, but I guess the LAN port on the Powerbook is enabled?

[jimothy]

Thanks for all the replies so far...

The Mac has OSX, and the ethernet port is enabled.

I guess thinking about it, UpTheIron and _dobbo_ have probably got a point. I haven't check that the cable I'm using actually works...

I have 2 network cables hanging on a hook by my hub, and I've used one of them before to successfully wire my laptop into the network, so perhaps I'm using the other one and its knackered.

I'll try some different cables tonight (including ones that are in use and working) and report back!