Re: IP swapping for network restart or reboot for ubuntu client

Hi all,
While observing the packet capture comparing the Microsoft DHCP server (the
one which is working fine in primary and failover) Vs the ISC DHCP server I
have observed the following:
In the Microsoft DHCP server, the IP address is bound to the client
identifier and IAID, I think this is how it is trying to bond the same IP
when pointed to the Microsoft DHCP cluster
Command Output:
PS C:\Users\Administrator> get-dhcpserverv4lease | select ipaddress,
clientid, hostname,addressstate,leaseexpirytime
cmdlet Get-DhcpServerv4Lease at command pipeline position 1
Supply values for the following parameters:
ScopeId: 192.168.0.0

IPAddress       : 192.168.0.152
clientid        : 9f-6e-85-24-00-02-00-00-ab-11-43-a9-47-2d-16-23-11-5e
hostname        : test.example.com
addressstate    : Active
leaseexpirytime : 6/16/2022 12:13:45 PM

In the above example(9f-6e-85-24 --> is the client IAID and
43-a9-47-2d-16-23-11-5e is the client identifier and not sure what is the
meaning for 00-02-00-00-ab )
Does any one has idea if we can use the client identifier value and IAID as
the unique element instead of mac address while granting the IP address in
ISC DHCP
Any help or suggestions is much appreciated

Thanks in Advance


On Tue, Jun 14, 2022 at 11:36 PM Kraishak Mahtha <[email protected]>
wrote:

> Hi  *Perl-list,*
>
> *I have been observing some weird behavior on packet capture, I am using
> the same command "netplan apply" and have been executing in the loop, I am
> getting the DHCP release packet for some trials only, and for other trials
> getting the discover packet directly bypassing the release packet I guess,
> My observation is it is swapping the IP only when we see the release
> packet.*
> *If anyone encounters the same behaviors and found a workaround please let
> me know*
>
> *Thanks in advance*
>
> On Tue, Jun 14, 2022 at 7:10 PM Kraishak Mahtha <[email protected]>
> wrote:
>
>> Hi Wayne,
>>
>> Thanks for sharing the link,
>>
>> I have observed that I am seeing this IP switch only if it is in a
>> primary-failover mode whereas if we run the DHCP server standalone we do
>> not see any issue and the IP is being constant, by any chance did you try
>> this case
>>
>> On Tue, Jun 14, 2022 at 2:56 PM Kraishak Mahtha <[email protected]>
>> wrote:
>>
>>> * Observed in the Ubuntu version 20.04
>>>
>>> On Tue, Jun 14, 2022 at 2:39 PM Kraishak Mahtha <[email protected]>
>>> wrote:
>>>
>>>> Hi all,
>>>> We are experiencing weird behavior with ISC's DHCP version 4.4.2. When
>>>> the Wintel(windows) clients use the ISC DHCP servers that are operating in
>>>> a primary-failover mode, then reboot or a renewal does not see any address
>>>> shuffle. When the Ubuntu clients use the ISC DHCP servers, we are observing
>>>> a periodic IP Address shuffle upon a reboot. This shuffling is not observed
>>>> when we are using a Microsoft DHCP solution. We are interested to know if
>>>> this issue is a known issue in the ISC database. If there is a workaround
>>>> to resolve this issue, please let us know.
>>>>
>>>> Thanks in Advance
>>>>
>>>

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