Merge pull request #86174 from openshift-cherrypick-robot/cherry-pick-85996-to-enterprise-4.16

Author: JoeAldinger

modules/optimizing-mtu-networking.adoc

@@ -7,7 +7,7 @@
 
 There are two important maximum transmission units (MTUs): the network interface controller (NIC) MTU and the cluster network MTU.
 
-The NIC MTU is only configured at the time of {product-title} installation. The MTU must be less than or equal to the maximum supported value of the NIC of your network. If you are optimizing for throughput, choose the largest possible value. If you are optimizing for lowest latency, choose a lower value.
+The NIC MTU is configured at the time of {product-title} installation, and you can also change the cluster's MTU as a Day 2 operation. See "Changing cluster network MTU" for more information. The MTU must be less than or equal to the maximum supported value of the NIC of your network. If you are optimizing for throughput, choose the largest possible value. If you are optimizing for lowest latency, choose a lower value.
 
 The OpenShift SDN network plugin overlay MTU must be less than the NIC MTU by 50 bytes at a minimum. This accounts for the SDN overlay header. So, on a normal ethernet network, this should be set to `1450`. On a jumbo frame ethernet network, this should be set to `8950`. These values should be set automatically by the Cluster Network Operator based on the NIC's configured MTU. Therefore, cluster administrators do not typically update these values. Amazon Web Services (AWS) and bare-metal environments support jumbo frame ethernet networks. This setting will help throughput, especially with transmission control protocol (TCP).
 

scalability_and_performance/optimization/optimizing-networking.adoc

@@ -27,6 +27,11 @@ VXLAN-offload does not reduce latency. However, CPU utilization is reduced even
 
 include::modules/optimizing-mtu-networking.adoc[leveloffset=+1]
 
+[role="_additional-resources"]
+.Additional resources
+
+* xref:../../networking/changing-cluster-network-mtu.adoc#changing-cluster-network-mtu[Changing cluster network MTU]
+
 include::modules/recommended-install-practices.adoc[leveloffset=+1]
 
 include::modules/ipsec-impact-networking.adoc[leveloffset=+1]