[Bug] - default MTU large than nat gateway limit

[BeckYeh]

Describe the bug
the default mtu 9001 is biger than nat gateway limit 8500, if I want to know how to change, there is no document. and how do I change it on EKS manage node ? all the pods eni are 9001 mtu

[elsaco]

@BeckYeh the ip command is available so you can temporarily change the MTU like sudo ip link set dev ens5 mtu 8500 for the 2nd network interface (ens5)

There is also /usr/lib/systemd/network/80-ec2.network file part of amazon-ec2-net-utils that configures your ENA network interfaces:

[ec2-user ~]$ cat /usr/lib/systemd/network/80-ec2.network
[Match]
Driver=ena ixgbevf vif

[Link]
MTUBytes=9001

--cut---

Change the MTUBytes according to your needs.

[BeckYeh]

On EKS manage node how to deal with it ?