Bug 2060905

Customers running Oracle often want to change the MTU of the loopback to 16 KiB (down from the default 64 KiB).

I'm not sure why this is. It seems Oracle sends MTU-sized UDP messages, however it can't handle such large messages as 64 KiB at once without dropping them. Reducing the MTU to 16 KiB resolves this.

As far as I know, every system running Oracle needs to manage the loopback MTU.

fixed upstream (1.41.6+) by https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1332

This work is done upstream but it is a large set of code changes and introduces undesirable risk to backport to RHEL 8. To ensure the stability of NetworkManager in RHEL8, this feature will be delivered in RHEL 9 and later. That work is being done on Bug 2073512.

For RHEL 8 and earlier, there are multiple viable workarounds depending on specific need. These include:

- a dummy interface to hold IP addresses
- a systemd unit to apply loopback settings on boot
- use the network initscript to manage loopback settings/IPs

These are documented on the knowledgebase at:

 How do I manage the "lo" loopback interface using NetworkManager? 
 https://access.redhat.com/solutions/2108251

(In reply to Jamie Bainbridge from comment #16)
> This work is done upstream but it is a large set of code changes and
> introduces undesirable risk to backport to RHEL 8. To ensure the stability
> of NetworkManager in RHEL8, this feature will be delivered in RHEL 9 and
> later. That work is being done on Bug 2073512.
> 
> For RHEL 8 and earlier, there are multiple viable workarounds depending on
> specific need. These include:
> 
> - a dummy interface to hold IP addresses
> - a systemd unit to apply loopback settings on boot
> - use the network initscript to manage loopback settings/IPs
> 
> These are documented on the knowledgebase at:
> 
>  How do I manage the "lo" loopback interface using NetworkManager? 
>  https://access.redhat.com/solutions/2108251

Hi Jamie,

does it mean that for RHEL 8 there does not need to be a release note for this feature?

Thanks for your clarification,
Jaroslav

(In reply to Jaroslav Klech from comment #17)
> does it mean that for RHEL 8 there does not need to be a release note for
> this feature?

I don't expect this would be in the Release Notes for RHEL 8.

This isn't a feature at all in RHEL 8, so we wouldn't say that we haven't put the feature in.

For customers who ask the specific "how do I do this?" question, we have the knowledgebase to answer that.

However, I expect this feature would be in the RHEL 9.2 Release Notes, and that work can be done on Bug 2073512 which includes this feature in 9.2.

lmk if I can help any time.

(In reply to Jamie Bainbridge from comment #18)
> (In reply to Jaroslav Klech from comment #17)
> > does it mean that for RHEL 8 there does not need to be a release note for
> > this feature?
> 
> I don't expect this would be in the Release Notes for RHEL 8.
> 
> This isn't a feature at all in RHEL 8, so we wouldn't say that we haven't
> put the feature in.
> 
> For customers who ask the specific "how do I do this?" question, we have the
> knowledgebase to answer that.
> 
> However, I expect this feature would be in the RHEL 9.2 Release Notes, and
> that work can be done on Bug 2073512 which includes this feature in 9.2.
> 
> lmk if I can help any time.

Based on the previous comment, im removing this from 8.8 RN schedule. Setting "No Doc Update", removing from tickets.yml