1. Proposed title of this feature request

Include net.ipv6.conf.IFNAME.hop_limit in the interface-specific safe sysctls list

2. What is the nature and description of the request?

The net.ipv6.conf.IFNAME.hop_limit sysctls configures the value put in the hop limit field of IPv6 packets. The hop limit field specifies the maximum number of layer 3 hops that the packet is allowed to traverse.

Customers need to configure this value to align with the values they are using for other elements of their overall system and network design.

Adding this sysctl to the iinterface-specific safe sysctls list avoids customers having to manage custom configuration to enable it as safe and maintain that configuration across OCP upgrades.

This sysctl appears to meet the criteria for inclusion in the interface-specific sysctls list because 

• it does not not have any influence on any other pod on the node
• it does must not allow a pod to harm the node's health
• it does not allow a pod to gain CPU or memory resources outside of the resource limit of the pod

3. Why does the customer need this? (List the business requirements here)

The customer's system and network design includes elements running as workloads on OpenShift and elements running outside of OpenShift.

The customer's system and network design uses a IPv6 hop limit that is different to the default value of this sysctl (64).

The customer does not want to have to maintain a custom interface-specific sysctls list including maintaining such a custom configuration across upgrades between OpenShift release where the contents of the default OCP interface-specific sysctls list may change over time.

4. List any affected packages or components.

Cluster Network Operator