iMac refuses to accept IP
Siegenthaler Tina
tina at ieu.uzh.ch
Thu Jun 28 07:22:53 UTC 2012
>>
>> Can you capture the second discover from the new client and take a look
>> at the Client Identifier? My guess is that the second packet contains a
>> 7 byte CI (just like the older clients) consisting of 0x01 and the MAC
>> address (013C075472CBC2). The value above seems to be those 7 bytes and
>> then 26 bytes of zero, which is not the same.
>>
>> Client Identifier is always the key from the server's perspective. If CI
>> changes it's a new host. This is mandatory per RFC2131/RFC4361.
>>
>> If that's the problem there is no DHCP compliant way of solving the
>> problem other than changing what the client sends as CI.
>>
>> --
>>
>
> Hi Peter
>
> Ah - yes. That sounds very plausible and I'll check that tomorrow morning first thing. It would explain why the DHCP server doesn't simply offer the same IP again on the second discover. I had been wondering as to why that was, because usually, the DHCP server will happily do so even if the old lease has not yet expired.
> If that is really the case, it will be difficult to change it on the client side, since this behavior is probably sitting somewhere in the firmware. I wonder if a different boot manager woul help here? Hm. Maybe I'll give it a try with rEFIt.
>
Indeed. This is the client identifier option of the first discover:
Option: (t=61,l=33) Client identifier
Option: (61) Client identifier
Length: 33
Value: 013C075472CBC20000000000000000000000000000000000...
And this the one of the second:
Option: (t=61,l=7) Client identifier
Option: (61) Client identifier
Length: 7
Value: 013C075472CBC2
Hardware type: Ethernet
Client MAC address: 3c:07:54:72:cb:c2 (3c:07:54:72:cb:c2)
Now that this is clear, I'll just have to find a workaround...
I'm going to try the following:
- Setting a DHCP client ID in the System Prefs (as proposed by Simon - thanks)
- If that doesn't help, use rEFIt as the boot manager
- If that doesn't help either.... ???
Tina
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