RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Bug 2048887 - [dhcpd] DHCPD not handing out infinite leases
Summary: [dhcpd] DHCPD not handing out infinite leases
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: dhcp
Version: 8.5
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Martin Osvald 🛹
QA Contact: rhel-cs-infra-services-qe
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2022-02-01 05:11 UTC by aygarg
Modified: 2022-04-12 11:01 UTC (History)
9 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2022-02-06 12:16:58 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Bugzilla 1900784 1 unspecified CLOSED [DOCS] Static DHCP assignment needed in IPI vSphere installations 2024-12-20 19:24:51 UTC
Red Hat Bugzilla 1942827 1 medium CLOSED DHCP requirements for IPI on vShere misleading 2023-09-15 01:03:59 UTC
Red Hat Issue Tracker RHELPLAN-110931 0 None None None 2022-02-03 09:22:05 UTC
Red Hat Knowledge Base (Solution) 5595281 0 None None None 2022-02-02 09:50:04 UTC
Red Hat Knowledge Base (Solution) 5704151 0 None None None 2022-02-02 09:50:04 UTC

Description aygarg 2022-02-01 05:11:56 UTC 
Description of problem:
OCP nodes are not able to retain the IPs after reboot as it always relies on the DHCP server while the expectation is to have the DHCP provided IPs configured as static IPs during the installation so that DHCP can be turned off post-installation.

As per the following document, during the OCP cluster deployment, DHCP assigned IPs are supposed to be configured as static IPs on the nodes which isn't seeming to be the case here. The expectation is to have the DHCP service turned off post-installation so that the IPs assigned to the nodes will remain as static IPs which will be retained forever without relying on the DHCP to be available every time the nodes are rebooted. As per the document, IP addresses have been reserved with an infinite lease yet the nodes are not coming up with the designated IPs after reboot without relying on the DHCP server. 

Please find the necessary DHCP & OCP cluster configuration details furnished below for further analysis.

https://docs.openshift.com/container-platform/4.8/installing/installing_bare_metal_ipi/ipi-install-prerequisites.html 

**IMPORTANT:**
"Reserving IP addresses so they become static IP addresses
Some administrators prefer to use static IP addresses so that each node’s IP address remains constant in the absence of a DHCP server. To use static IP addresses in the OpenShift Container Platform cluster, reserve the IP addresses with an infinite lease. During deployment, the installer will reconfigure the NICs from DHCP assigned addresses to static IP addresses. NICs with DHCP leases that are not infinite will remain configured to use DHCP."


Version-Release number of selected component (if applicable):
OCP 4.8.25 (IPI)/Baremetal Platform


How reproducible:
Every time in customer's environment.



Actual results:
The node's IP address changes after reboot.

Expected results:
IP address must remain persistent after reboot when DHCP is turned off.

Additional info:
The DHCP is used on the provisioning node along with dnsmasq to allow node get the ip address.

The reported behavior is noticed right after successful installation of the cluster & when the nodes are rebooted for testing purpose or as a result of performing some change on the cluster. The customer purposefully turns off DHCP once the cluster installation is successful just to verify if the IPs are persistent during reboot & they don't rely on the DHCP server anymore but it's not working as expected as all the time, it looks for the DHCP server to get the IPs during reboot.
Comment 21 Martin Osvald 🛹 2022-02-06 12:16:58 UTC 
I was able to reproduce on RHEL8.5 and can confirm this works on RHEL7.9.

This is not a bug but an intended change in behavior introduced by the below upstream patch (since upstream 4.3.5, RHEL8.x is based on 4.3.6):

https://github.com/isc-projects/dhcp/commit/68507137e1cbd783b6cb7ce84a4805c96af6eb5e
~~~
- Altered DHCPv4 lease time calculation to avoid roll over errors on 64-bit
  OS systems when using -1 or large values for default-lease-time.  Rollover
  values will be replaced with 0x7FFFFFFF - 1.  This alleviates unintentionally
  short expiration times being handed out when infinite lease times (-1) in
  conjuction with failover.
  [ISC-Bugs #41976]
~~~

This means dhcp no longer supports infinite leases. This may sound wrong to you, but RFC itself allows this behavior:

https://datatracker.ietf.org/doc/html/rfc2131#section-2.2
~~~
                                        The client may ask for a
   permanent assignment by asking for an infinite lease.  Even when
   assigning "permanent" addresses, a server may choose to give out
   lengthy but non-infinite leases to allow detection of the fact that
   the client has been retired.
~~~

There is no client/server side configuration directive that could workaround the responsible code behavior in ack_lease().
Note You need to log in before you can comment on or make changes to this bug.